This allows cleanup actions to be registered to be called just before a
particular memory context's contents are flushed (either by deletion or
MemoryContextReset). The patch in itself has no use-cases for this, but
several likely reasons for wanting this exist.
In passing, per discussion, rearrange some boolean fields in struct
MemoryContextData so as to avoid wasted padding space. For safety,
this requires making allowInCritSection's existence unconditional;
but I think that's a better approach than what was there anyway.
Use a different A_Expr_Kind for LIKE/ILIKE/SIMILAR TO constructs, so that
they can be distinguished from direct invocation of the underlying
operators. Also, postpone selection of the operator name when transforming
"x IN (select)" to "x = ANY (select)", so that those syntaxes can be told
apart at parse analysis time.
I had originally thought I'd also have to do something special for the
syntaxes IS NOT DISTINCT FROM, IS NOT DOCUMENT, and x NOT IN (SELECT...),
which the grammar translates as though they were NOT (construct).
On reflection though, we can distinguish those cases reliably by noting
whether the parse location shown for the NOT is the same as for its child
node. This only requires tweaking the parse locations for NOT IN, which
I've done here.
These changes should have no effect outside the parser; they're just in
support of being able to give accurate warnings for planned operator
precedence changes.
We did not need a location tag on NullTest or BooleanTest before, because
no error messages referred directly to their locations. That's planned
to change though, so add these fields in a separate housekeeping commit.
Catversion bump because stored rules may change.
transformExpr() has for many years had provisions to do nothing when
applied to an already-transformed expression tree. However, this was
always ugly and of dubious reliability, so we'd be much better off without
it. The primary historical reason for it was that gram.y sometimes
returned multiple links to the same subexpression, which is no longer true
as of my BETWEEN fixes. We'd also grown some lazy hacks in CREATE TABLE
LIKE (failing to distinguish between raw and already-transformed index
specifications) and one or two other places.
This patch removes the need for and support for re-transforming already
transformed expressions. The index case is dealt with by adding a flag
to struct IndexStmt to indicate that it's already been transformed;
which has some benefit anyway in that tablecmds.c can now Assert that
transformation has happened rather than just assuming. The other main
reason was some rather sloppy code for array type coercion, which can
be fixed (and its performance improved too) by refactoring.
I did leave transformJoinUsingClause() still constructing expressions
containing untransformed operator nodes being applied to Vars, so that
transformExpr() still has to allow Var inputs. But that's a much narrower,
and safer, special case than before, since Vars will never appear in a raw
parse tree, and they don't have any substructure to worry about.
In passing fix some oversights in the patch that added CREATE INDEX
IF NOT EXISTS (missing processing of IndexStmt.if_not_exists). These
appear relatively harmless, but still sloppy coding practice.
Previously, gram.y itself converted BETWEEN into AND (or AND/OR) nests of
expression comparisons. This was always as bogus as could be, but fixing
it hasn't risen to the top of the to-do list. The present patch invents an
A_Expr representation for BETWEEN expressions, and does the expansion to
comparison trees in parse_expr.c which is at least a slightly saner place
to be doing semantic conversions. There should be no change in the post-
parse-analysis results.
This does nothing for the semantic issues with BETWEEN (dubious connection
to btree-opclass semantics, and multiple evaluation of possibly volatile
subexpressions) ... but it's a necessary preliminary step before we could
fix any of that. The main immediate benefit is that preserving BETWEEN as
an identifiable raw-parse-tree construct will enable better error messages.
While at it, fix the code so that multiply-referenced subexpressions are
physically duplicated before being passed through transformExpr(). This
gets rid of one of the principal reasons why transformExpr() has
historically had to allow already-processed input.
Replace some bogus "x[1]" declarations with "x[FLEXIBLE_ARRAY_MEMBER]".
Aside from being more self-documenting, this should help prevent bogus
warnings from static code analyzers and perhaps compiler misoptimizations.
This patch is just a down payment on eliminating the whole problem, but
it gets rid of a lot of easy-to-fix cases.
Note that the main problem with doing this is that one must no longer rely
on computing sizeof(the containing struct), since the result would be
compiler-dependent. Instead use offsetof(struct, lastfield). Autoconf
also warns against spelling that offsetof(struct, lastfield[0]).
Michael Paquier, review and additional fixes by me.
The previous coding in EXPLAIN always labeled a ModifyTable node with the
name of the target table affected by its first child plan. When originally
written, this was necessarily the parent table of the inheritance tree,
so everything was unconfusing. But when we added NO INHERIT constraints,
it became possible for the parent table to be deleted from the plan by
constraint exclusion while still leaving child tables present. This led to
the ModifyTable plan node being labeled with the first surviving child,
which was deemed confusing. Fix it by retaining the parent table's RT
index in a new field in ModifyTable.
Etsuro Fujita, reviewed by Ashutosh Bapat and myself
This reverts commit 1826987a46.
The overall design was deemed unacceptable, in discussion following the
previous commit message; we might find some parts of it still
salvageable, but I don't want to be on the hook for fixing it, so let's
wait until we have a new patch.
This allows access to get_object_address from SQL, which is useful to
obtain OID addressing information from data equivalent to that emitted
by the parser. This is necessary infrastructure of a project to let
replication systems propagate object dropping events to remote servers,
where the schema might be different than the server originating the
DROP.
This patch also adds support for OBJECT_DEFAULT to get_object_address;
that is, it is now possible to refer to a column's default value.
Catalog version bumped due to the new function.
Reviewed by Stephen Frost, Heikki Linnakangas, Robert Haas, Andres
Freund, Abhijit Menon-Sen, Adam Brightwell.
The previous representation using a boolean column for each attribute
would not scale as well as we want to add further attributes.
Extra auxilliary functions are added to go along with this change, to
make up for the lost convenience of access of the old representation.
Catalog version bumped due to change in catalogs and the new functions.
Author: Adam Brightwell, minor tweaks by Álvaro
Reviewed by: Stephen Frost, Andres Freund, Álvaro Herrera
Apart from enabling comments on domain constraints, this enables a
future project to replicate object dropping to remote servers: with the
current mechanism there's no way to distinguish between the two types of
constraints, so there's no way to know what to drop.
Also added support for the domain constraint comments in psql's \dd and
pg_dump.
Catalog version bumped due to the change in ObjectType enum.
This patch adds a function that replaces a bms_membership() test followed
by a bms_singleton_member() call, performing both the test and the
extraction of a singleton set's member in one scan of the bitmapset.
The performance advantage over the old way is probably minimal in current
usage, but it seems worthwhile on notational grounds anyway.
David Rowley
This patch adds a way of iterating through the members of a bitmapset
nondestructively, unlike the old way with bms_first_member(). While
bms_next_member() is very slightly slower than bms_first_member()
(at least for typical-size bitmapsets), eliminating the need to palloc
and pfree a temporary copy of the target bitmapset is a significant win.
So this method should be preferred in all cases where a temporary copy
would be necessary.
Tom Lane, with suggestions from Dean Rasheed and David Rowley
As pointed out by Robert, we should really have named pg_rowsecurity
pg_policy, as the objects stored in that catalog are policies. This
patch fixes that and updates the column names to start with 'pol' to
match the new catalog name.
The security consideration for COPY with row level security, also
pointed out by Robert, has also been addressed by remembering and
re-checking the OID of the relation initially referenced during COPY
processing, to make sure it hasn't changed under us by the time we
finish planning out the query which has been built.
Robert and Alvaro also commented on missing OCLASS and OBJECT entries
for POLICY (formerly ROWSECURITY or POLICY, depending) in various
places. This patch fixes that too, which also happens to add the
ability to COMMENT on policies.
In passing, attempt to improve the consistency of messages, comments,
and documentation as well. This removes various incarnations of
'row-security', 'row-level security', 'Row-security', etc, in favor
of 'policy', 'row level security' or 'row_security' as appropriate.
Happy Thanksgiving!
Make it work more like FDW plans do: instead of assuming that there are
expressions in a CustomScan plan node that the core code doesn't know
about, insist that all subexpressions that need planner attention be in
a "custom_exprs" list in the Plan representation. (Of course, the
custom plugin can break the list apart again at executor initialization.)
This lets us revert the parts of the patch that exposed setrefs.c and
subselect.c processing to the outside world.
Also revert the GetSpecialCustomVar stuff in ruleutils.c; that concept
may work in future, but it's far from fully baked right now.
Instead of register_custom_path_provider and a CreateCustomScanPath
callback, let's just provide a standard function hook in set_rel_pathlist.
This is more flexible than what was previously committed, is more like the
usual conventions for planner hooks, and requires less support code in the
core. We had discussed this design (including centralizing the
set_cheapest() calls) back in March or so, so I'm not sure why it wasn't
done like this already.
There seems no prospect that any of this will ever be useful, and indeed
it's questionable whether some of it would work if it ever got called;
it's certainly not been exercised in a very long time, if ever. So let's
get rid of it, and make the comments about mark/restore in execAmi.c less
wishy-washy.
The mark/restore support for Result nodes is also currently dead code,
but that's due to planner limitations not because it's impossible that
it could be useful. So I left it in.
Get rid of the pernicious entanglement between planner and executor headers
introduced by commit 0b03e5951b.
Also, rearrange the CustomFoo struct/typedef definitions so that all the
typedef names are seen as used by the compiler. Without this pgindent
will mess things up a bit, which is not so important perhaps, but it also
removes a bizarre discrepancy between the declaration arrangement used for
CustomExecMethods and that used for CustomScanMethods and
CustomPathMethods.
Clean up the commentary around ExecSupportsMarkRestore to reflect the
rather large change in its API.
Const-ify register_custom_path_provider's argument. This necessitates
casting away const in the function, but that seems better than forcing
callers of the function to do so (or else not const-ify their method
pointer structs, which was sort of the whole point).
De-export fix_expr_common. I don't like the exporting of fix_scan_expr
or replace_nestloop_params either, but this one surely has got little
excuse.
At one time it wasn't terribly important what column names were associated
with the fields of a composite Datum, but since the introduction of
operations like row_to_json(), it's important that looking up the rowtype
ID embedded in the Datum returns the column names that users would expect.
That did not work terribly well before this patch: you could get the column
names of the underlying table, or column aliases from any level of the
query, depending on minor details of the plan tree. You could even get
totally empty field names, which is disastrous for cases like row_to_json().
To fix this for whole-row Vars, look to the RTE referenced by the Var, and
make sure its column aliases are applied to the rowtype associated with
the result Datums. This is a tad scary because we might have to return
a transient RECORD type even though the Var is declared as having some
named rowtype. In principle it should be all right because the record
type will still be physically compatible with the named rowtype; but
I had to weaken one Assert in ExecEvalConvertRowtype, and there might be
third-party code containing similar assumptions.
Similarly, RowExprs have to be willing to override the column names coming
from a named composite result type and produce a RECORD when the column
aliases visible at the site of the RowExpr differ from the underlying
table's column names.
In passing, revert the decision made in commit 398f70ec07 to add
an alias-list argument to ExecTypeFromExprList: better to provide that
functionality in a separate function. This also reverts most of the code
changes in d685814835, which we don't need because we're no longer
depending on the tupdesc found in the child plan node's result slot to be
blessed.
Back-patch to 9.4, but not earlier, since this solution changes the results
in some cases that users might not have realized were buggy. We'll apply a
more restricted form of this patch in older branches.
This allows extension modules to define their own methods for
scanning a relation, and get the core code to use them. It's
unclear as yet how much use this capability will find, but we
won't find out if we never commit it.
KaiGai Kohei, reviewed at various times and in various levels
of detail by Shigeru Hanada, Tom Lane, Andres Freund, Álvaro
Herrera, and myself.
This clause changes the behavior of SELECT locking clauses in the
presence of locked rows: instead of causing a process to block waiting
for the locks held by other processes (or raise an error, with NOWAIT),
SKIP LOCKED makes the new reader skip over such rows. While this is not
appropriate behavior for general purposes, there are some cases in which
it is useful, such as queue-like tables.
Catalog version bumped because this patch changes the representation of
stored rules.
Reviewed by Craig Ringer (based on a previous attempt at an
implementation by Simon Riggs, who also provided input on the syntax
used in the current patch), David Rowley, and Álvaro Herrera.
Author: Thomas Munro
Building on the updatable security-barrier views work, add the
ability to define policies on tables to limit the set of rows
which are returned from a query and which are allowed to be added
to a table. Expressions defined by the policy for filtering are
added to the security barrier quals of the query, while expressions
defined to check records being added to a table are added to the
with-check options of the query.
New top-level commands are CREATE/ALTER/DROP POLICY and are
controlled by the table owner. Row Security is able to be enabled
and disabled by the owner on a per-table basis using
ALTER TABLE .. ENABLE/DISABLE ROW SECURITY.
Per discussion, ROW SECURITY is disabled on tables by default and
must be enabled for policies on the table to be used. If no
policies exist on a table with ROW SECURITY enabled, a default-deny
policy is used and no records will be visible.
By default, row security is applied at all times except for the
table owner and the superuser. A new GUC, row_security, is added
which can be set to ON, OFF, or FORCE. When set to FORCE, row
security will be applied even for the table owner and superusers.
When set to OFF, row security will be disabled when allowed and an
error will be thrown if the user does not have rights to bypass row
security.
Per discussion, pg_dump sets row_security = OFF by default to ensure
that exports and backups will have all data in the table or will
error if there are insufficient privileges to bypass row security.
A new option has been added to pg_dump, --enable-row-security, to
ask pg_dump to export with row security enabled.
A new role capability, BYPASSRLS, which can only be set by the
superuser, is added to allow other users to be able to bypass row
security using row_security = OFF.
Many thanks to the various individuals who have helped with the
design, particularly Robert Haas for his feedback.
Authors include Craig Ringer, KaiGai Kohei, Adam Brightwell, Dean
Rasheed, with additional changes and rework by me.
Reviewers have included all of the above, Greg Smith,
Jeff McCormick, and Robert Haas.
This enables changing permanent (logged) tables to unlogged and
vice-versa.
(Docs for ALTER TABLE / SET TABLESPACE got shuffled in an order that
hopefully makes more sense than the original.)
Author: Fabrízio de Royes Mello
Reviewed by: Christoph Berg, Andres Freund, Thom Brown
Some tweaking by Álvaro Herrera
As 'ALTER TABLESPACE .. MOVE ALL' really didn't change the tablespace
but instead changed objects inside tablespaces, it made sense to
rework the syntax and supporting functions to operate under the
'ALTER (TABLE|INDEX|MATERIALIZED VIEW)' syntax and to be in
tablecmds.c.
Pointed out by Alvaro, who also suggested the new syntax.
Back-patch to 9.4.
This command provides an automated way to create foreign table definitions
that match remote tables, thereby reducing tedium and chances for error.
In this patch, we provide the necessary core-server infrastructure and
implement the feature fully in the postgres_fdw foreign-data wrapper.
Other wrappers will throw a "feature not supported" error until/unless
they are updated.
Ronan Dunklau and Michael Paquier, additional work by me
The assertion failed if WAL_DEBUG or LWLOCK_STATS was enabled; fix that by
using separate memory contexts for the allocations made within those code
blocks.
This patch introduces a mechanism for marking any memory context as allowed
in a critical section. Previously ErrorContext was exempt as a special case.
Instead of a blanket exception of the checkpointer process, only exempt the
memory context used for the pending ops hash table.
ExecMakeTableFunctionResult evaluated the arguments for a function-in-FROM
in the query-lifespan memory context. This is insignificant in simple
cases where the function relation is scanned only once; but if the function
is in a sub-SELECT or is on the inside of a nested loop, any memory
consumed during argument evaluation can add up quickly. (The potential for
trouble here had been foreseen long ago, per existing comments; but we'd
not previously seen a complaint from the field about it.) To fix, create
an additional temporary context just for this purpose.
Per an example from MauMau. Back-patch to all active branches.
This SQL-standard feature allows a sub-SELECT yielding multiple columns
(but only one row) to be used to compute the new values of several columns
to be updated. While the same results can be had with an independent
sub-SELECT per column, such a workaround can require a great deal of
duplicated computation.
The standard actually says that the source for a multi-column assignment
could be any row-valued expression. The implementation used here is
tightly tied to our existing sub-SELECT support and can't handle other
cases; the Bison grammar would have some issues with them too. However,
I don't feel too bad about this since other cases can be converted into
sub-SELECTs. For instance, "SET (a,b,c) = row_valued_function(x)" could
be written "SET (a,b,c) = (SELECT * FROM row_valued_function(x))".
Since most of the system thinks AND and OR are N-argument expressions
anyway, let's have the grammar generate a representation of that form when
dealing with input like "x AND y AND z AND ...", rather than generating
a deeply-nested binary tree that just has to be flattened later by the
planner. This avoids stack overflow in parse analysis when dealing with
queries having more than a few thousand such clauses; and in any case it
removes some rather unsightly inconsistencies, since some parts of parse
analysis were generating N-argument ANDs/ORs already.
It's still possible to get a stack overflow with weirdly parenthesized
input, such as "x AND (y AND (z AND ( ... )))", but such cases are not
mainstream usage. The maximum depth of parenthesization is already
limited by Bison's stack in such cases, anyway, so that the limit is
probably fairly platform-independent.
Patch originally by Gurjeet Singh, heavily revised by me
Views which are marked as security_barrier must have their quals
applied before any user-defined quals are called, to prevent
user-defined functions from being able to see rows which the
security barrier view is intended to prevent them from seeing.
Remove the restriction on security barrier views being automatically
updatable by adding a new securityQuals list to the RTE structure
which keeps track of the quals from security barrier views at each
level, independently of the user-supplied quals. When RTEs are
later discovered which have securityQuals populated, they are turned
into subquery RTEs which are marked as security_barrier to prevent
any user-supplied quals being pushed down (modulo LEAKPROOF quals).
Dean Rasheed, reviewed by Craig Ringer, Simon Riggs, KaiGai Kohei
Until now, when executing an aggregate function as a window function
within a window with moving frame start (that is, any frame start mode
except UNBOUNDED PRECEDING), we had to recalculate the aggregate from
scratch each time the frame head moved. This patch allows an aggregate
definition to include an alternate "moving aggregate" implementation
that includes an inverse transition function for removing rows from
the aggregate's running state. As long as this can be done successfully,
runtime is proportional to the total number of input rows, rather than
to the number of input rows times the average frame length.
This commit includes the core infrastructure, documentation, and regression
tests using user-defined aggregates. Follow-on commits will update some
of the built-in aggregates to use this feature.
David Rowley and Florian Pflug, reviewed by Dean Rasheed; additional
hacking by me
For variadic functions (other than VARIADIC ANY), the syntaxes foo(x,y,...)
and foo(VARIADIC ARRAY[x,y,...]) should be considered equivalent, since the
former is converted to the latter at parse time. They have indeed been
equivalent, in all releases before 9.3. However, commit 75b39e790 made an
ill-considered decision to record which syntax had been used in FuncExpr
nodes, and then to make equal() test that in checking node equality ---
which caused the syntaxes to not be seen as equivalent by the planner.
This is the underlying cause of bug #9817 from Dmitry Ryabov.
It might seem that a quick fix would be to make equal() disregard
FuncExpr.funcvariadic, but the same commit made that untenable, because
the field actually *is* semantically significant for some VARIADIC ANY
functions. This patch instead adopts the approach of redefining
funcvariadic (and aggvariadic, in HEAD) as meaning that the last argument
is a variadic array, whether it got that way by parser intervention or was
supplied explicitly by the user. Therefore the value will always be true
for non-ANY variadic functions, restoring the principle of equivalence.
(However, the planner will continue to consider use of VARIADIC as a
meaningful difference for VARIADIC ANY functions, even though some such
functions might disregard it.)
In HEAD, this change lets us simplify the decompilation logic in
ruleutils.c, since the funcvariadic/aggvariadic flag tells directly whether
to print VARIADIC. However, in 9.3 we have to continue to cope with
existing stored rules/views that might contain the previous definition.
Fortunately, this just means no change in ruleutils.c, since its existing
behavior effectively ignores funcvariadic for all cases other than VARIADIC
ANY functions.
In HEAD, bump catversion to reflect the fact that FuncExpr.funcvariadic
changed meanings; this is sort of pro forma, since I don't believe any
built-in views are affected.
Unfortunately, this patch doesn't magically fix everything for affected
9.3 users. After installing 9.3.5, they might need to recreate their
rules/views/indexes containing variadic function calls in order to get
everything consistent with the new definition. As in the cited bug,
the symptom of a problem would be failure to use a nominally matching
index that has a variadic function call in its definition. We'll need
to mention this in the 9.3.5 release notes.
This was already documented a few lines further down, but the comment
just beside the field declaration could be misleading. Per gripe
from Kyotaro Horiguchi.
If the name lookups come to different conclusions due to concurrent
activity, we might perform some parts of the DDL on a different table
than other parts. At least in the case of CREATE INDEX, this can be
used to cause the permissions checks to be performed against a
different table than the index creation, allowing for a privilege
escalation attack.
This changes the calling convention for DefineIndex, CreateTrigger,
transformIndexStmt, transformAlterTableStmt, CheckIndexCompatible
(in 9.2 and newer), and AlterTable (in 9.1 and older). In addition,
CheckRelationOwnership is removed in 9.2 and newer and the calling
convention is changed in older branches. A field has also been added
to the Constraint node (FkConstraint in 8.4). Third-party code calling
these functions or using the Constraint node will require updating.
Report by Andres Freund. Patch by Robert Haas and Andres Freund,
reviewed by Tom Lane.
Security: CVE-2014-0062
Previously we were piggybacking on transaction ID parameters to freeze
multixacts; but since there isn't necessarily any relationship between
rates of Xid and multixact consumption, this turns out not to be a good
idea.
Therefore, we now have multixact-specific freezing parameters:
vacuum_multixact_freeze_min_age: when to remove multis as we come across
them in vacuum (default to 5 million, i.e. early in comparison to Xid's
default of 50 million)
vacuum_multixact_freeze_table_age: when to force whole-table scans
instead of scanning only the pages marked as not all visible in
visibility map (default to 150 million, same as for Xids). Whichever of
both which reaches the 150 million mark earlier will cause a whole-table
scan.
autovacuum_multixact_freeze_max_age: when for cause emergency,
uninterruptible whole-table scans (default to 400 million, double as
that for Xids). This means there shouldn't be more frequent emergency
vacuuming than previously, unless multixacts are being used very
rapidly.
Backpatch to 9.3 where multixacts were made to persist enough to require
freezing. To avoid an ABI break in 9.3, VacuumStmt has a couple of
fields in an unnatural place, and StdRdOptions is split in two so that
the newly added fields can go at the end.
Patch by me, reviewed by Robert Haas, with additional input from Andres
Freund and Tom Lane.
Replication slots are a crash-safe data structure which can be created
on either a master or a standby to prevent premature removal of
write-ahead log segments needed by a standby, as well as (with
hot_standby_feedback=on) pruning of tuples whose removal would cause
replication conflicts. Slots have some advantages over existing
techniques, as explained in the documentation.
In a few places, we refer to the type of replication slots introduced
by this patch as "physical" slots, because forthcoming patches for
logical decoding will also have slots, but with somewhat different
properties.
Andres Freund and Robert Haas
Add the ability to specify the objects to move by who those objects are
owned by (as relowner) and change ALL to mean ALL objects. This
makes the command always operate against a well-defined set of objects
and not have the objects-to-be-moved based on the role of the user
running the command.
Per discussion with Simon and Tom.
Tablespaces have a few options which can be set on them to give PG hints
as to how the tablespace behaves (perhaps it's faster for sequential
scans, or better able to handle random access, etc). These options were
only available through the ALTER TABLESPACE command.
This adds the ability to set these options at CREATE TABLESPACE time,
removing the need to do both a CREATE TABLESPACE and ALTER TABLESPACE to
get the correct options set on the tablespace.
Vik Fearing, reviewed by Michael Paquier.
This adds a 'MOVE' sub-command to ALTER TABLESPACE which allows moving sets of
objects from one tablespace to another. This can be extremely handy and avoids
a lot of error-prone scripting. ALTER TABLESPACE ... MOVE will only move
objects the user owns, will notify the user if no objects were found, and can
be used to move ALL objects or specific types of objects (TABLES, INDEXES, or
MATERIALIZED VIEWS).
This patch introduces generic support for ordered-set and hypothetical-set
aggregate functions, as well as implementations of the instances defined in
SQL:2008 (percentile_cont(), percentile_disc(), rank(), dense_rank(),
percent_rank(), cume_dist()). We also added mode() though it is not in the
spec, as well as versions of percentile_cont() and percentile_disc() that
can compute multiple percentile values in one pass over the data.
Unlike the original submission, this patch puts full control of the sorting
process in the hands of the aggregate's support functions. To allow the
support functions to find out how they're supposed to sort, a new API
function AggGetAggref() is added to nodeAgg.c. This allows retrieval of
the aggregate call's Aggref node, which may have other uses beyond the
immediate need. There is also support for ordered-set aggregates to
install cleanup callback functions, so that they can be sure that
infrastructure such as tuplesort objects gets cleaned up.
In passing, make some fixes in the recently-added support for variadic
aggregates, and make some editorial adjustments in the recent FILTER
additions for aggregates. Also, simplify use of IsBinaryCoercible() by
allowing it to succeed whenever the target type is ANY or ANYELEMENT.
It was inconsistent that it dealt with other polymorphic target types
but not these.
Atri Sharma and Andrew Gierth; reviewed by Pavel Stehule and Vik Fearing,
and rather heavily editorialized upon by Tom Lane
SQL-standard TABLE() is a subset of UNNEST(); they deal with arrays and
other collection types. This feature, however, deals with set-returning
functions. Use a different syntax for this feature to keep open the
possibility of implementing the standard TABLE().
This patch adds the ability to write TABLE( function1(), function2(), ...)
as a single FROM-clause entry. The result is the concatenation of the
first row from each function, followed by the second row from each
function, etc; with NULLs inserted if any function produces fewer rows than
others. This is believed to be a much more useful behavior than what
Postgres currently does with multiple SRFs in a SELECT list.
This syntax also provides a reasonable way to combine use of column
definition lists with WITH ORDINALITY: put the column definition list
inside TABLE(), where it's clear that it doesn't control the ordinality
column as well.
Also implement SQL-compliant multiple-argument UNNEST(), by turning
UNNEST(a,b,c) into TABLE(unnest(a), unnest(b), unnest(c)).
The SQL standard specifies TABLE() with only a single function, not
multiple functions, and it seems to require an implicit UNNEST() which is
not what this patch does. There may be something wrong with that reading
of the spec, though, because if it's right then the spec's TABLE() is just
a pointless alternative spelling of UNNEST(). After further review of
that, we might choose to adopt a different syntax for what this patch does,
but in any case this functionality seems clearly worthwhile.
Andrew Gierth, reviewed by Zoltán Böszörményi and Heikki Linnakangas, and
significantly revised by me
Bug #8591 from Claudio Freire demonstrates that get_eclass_for_sort_expr
must be able to compute valid em_nullable_relids for any new equivalence
class members it creates. I'd worried about this in the commit message
for db9f0e1d9a, but claimed that it wasn't a
problem because multi-member ECs should already exist when it runs. That
is transparently wrong, though, because this function is also called by
initialize_mergeclause_eclasses, which runs during deconstruct_jointree.
The example given in the bug report (which the new regression test item
is based upon) fails because the COALESCE() expression is first seen by
initialize_mergeclause_eclasses rather than process_equivalence.
Fixing this requires passing the appropriate nullable_relids set to
get_eclass_for_sort_expr, and it requires new code to compute that set
for top-level expressions such as ORDER BY, GROUP BY, etc. We store
the top-level nullable_relids in a new field in PlannerInfo to avoid
computing it many times. In the back branches, I've added the new
field at the end of the struct to minimize ABI breakage for planner
plugins. There doesn't seem to be a good alternative to changing
get_eclass_for_sort_expr's API signature, though. There probably aren't
any third-party extensions calling that function directly; moreover,
if there are, they probably need to think about what to pass for
nullable_relids anyway.
Back-patch to 9.2, like the previous patch in this area.
Pending patches for logical replication will use this to determine
which columns of a tuple ought to be considered as its candidate key.
Andres Freund, with minor, mostly cosmetic adjustments by me
DISCARD ALL will now discard cached sequence information, as well.
Fabrízio de Royes Mello, reviewed by Zoltán Böszörményi, with some
further tweaks by me.
There's no inherent reason why an aggregate function can't be variadic
(even VARIADIC ANY) if its transition function can handle the case.
Indeed, this patch to add the feature touches none of the planner or
executor, and little of the parser; the main missing stuff was DDL and
pg_dump support.
It is true that variadic aggregates can create the same sort of ambiguity
about parameters versus ORDER BY keys that was complained of when we
(briefly) had both one- and two-argument forms of string_agg(). However,
the policy formed in response to that discussion only said that we'd not
create any built-in aggregates with varying numbers of arguments, not that
we shouldn't allow users to do it. So the logical extension of that is
we can allow users to make variadic aggregates as long as we're wary about
shipping any such in core.
In passing, this patch allows aggregate function arguments to be named, to
the extent of remembering the names in pg_proc and dumping them in pg_dump.
You can't yet call an aggregate using named-parameter notation. That seems
like a likely future extension, but it'll take some work, and it's not what
this patch is really about. Likewise, there's still some work needed to
make window functions handle VARIADIC fully, but I left that for another
day.
initdb forced because of new aggvariadic field in Aggref parse nodes.
The planner largely failed to consider the possibility that a
PlaceHolderVar's expression might contain a lateral reference to a Var
coming from somewhere outside the PHV's syntactic scope. We had a previous
report of a problem in this area, which I tried to fix in a quick-hack way
in commit 4da6439bd8, but Antonin Houska
pointed out that there were still some problems, and investigation turned
up other issues. This patch largely reverts that commit in favor of a more
thoroughly thought-through solution. The new theory is that a PHV's
ph_eval_at level cannot be higher than its original syntactic level. If it
contains lateral references, those don't change the ph_eval_at level, but
rather they create a lateral-reference requirement for the ph_eval_at join
relation. The code in joinpath.c needs to handle that.
Another issue is that createplan.c wasn't handling nested PlaceHolderVars
properly.
In passing, push knowledge of lateral-reference checks for join clauses
into join_clause_is_movable_to. This is mainly so that FDWs don't need
to deal with it.
This patch doesn't fix the original join-qual-placement problem reported by
Jeremy Evans (and indeed, one of the new regression test cases shows the
wrong answer because of that). But the PlaceHolderVar problems need to be
fixed before that issue can be addressed, so committing this separately
seems reasonable.
The planner logic that attempted to make a preliminary estimate of the
ph_needed levels for PlaceHolderVars seems to be completely broken by
lateral references. Fortunately, the potential join order optimization
that this code supported seems to be of relatively little value in
practice; so let's just get rid of it rather than trying to fix it.
Getting rid of this allows fairly substantial simplifications in
placeholder.c, too, so planning in such cases should be a bit faster.
Issue noted while pursuing bugs reported by Jeremy Evans and Antonin
Houska, though this doesn't in itself fix either of their reported cases.
What this does do is prevent an Assert crash in the kind of query
illustrated by the added regression test. (I'm not sure that the plan for
that query is stable enough across platforms to be usable as a regression
test output ... but we'll soon find out from the buildfarm.)
Back-patch to 9.3. The problem case can't arise without LATERAL, so
no need to touch older branches.
Use of this function has spread into the parser and rewriter, so it seems
like time to pull it out of the optimizer and put it into the more central
nodeFuncs module. This eliminates the need to #include optimizer/clauses.h
in most of the calling files, demonstrating that this function was indeed a
bit outside the normal code reference patterns.
It's possible to drop a column from an input table of a JOIN clause in a
view, if that column is nowhere actually referenced in the view. But it
will still be there in the JOIN clause's joinaliasvars list. We used to
replace such entries with NULL Const nodes, which is handy for generation
of RowExpr expansion of a whole-row reference to the view. The trouble
with that is that it can't be distinguished from the situation after
subquery pull-up of a constant subquery output expression below the JOIN.
Instead, replace such joinaliasvars with null pointers (empty expression
trees), which can't be confused with pulled-up expressions. expandRTE()
still emits the old convention, though, for convenience of RowExpr
generation and to reduce the risk of breaking extension code.
In HEAD and 9.3, this patch also fixes a problem with some new code in
ruleutils.c that was failing to cope with implicitly-casted joinaliasvars
entries, as per recent report from Feike Steenbergen. That oversight was
because of an inadequate description of the data structure in parsenodes.h,
which I've now corrected. There were some pre-existing oversights of the
same ilk elsewhere, which I believe are now all fixed.
For simple views which are automatically updatable, this patch allows
the user to specify what level of checking should be done on records
being inserted or updated. For 'LOCAL CHECK', new tuples are validated
against the conditionals of the view they are being inserted into, while
for 'CASCADED CHECK' the new tuples are validated against the
conditionals for all views involved (from the top down).
This option is part of the SQL specification.
Dean Rasheed, reviewed by Pavel Stehule
This is SQL-standard with a few extensions, namely support for
subqueries and outer references in clause expressions.
catversion bump due to change in Aggref and WindowFunc.
David Fetter, reviewed by Dean Rasheed.
This allows reads to continue without any blocking while a REFRESH
runs. The new data appears atomically as part of transaction
commit.
Review questioned the Assert that a matview was not a system
relation. This will be addressed separately.
Reviewed by Hitoshi Harada, Robert Haas, Andres Freund.
Merged after review with security patch f3ab5d4.
This patch gets rid of the concept of, and infrastructure for,
non-canonical PathKeys; we now only ever create canonical pathkey lists.
The need for non-canonical pathkeys came from the desire to have
grouping_planner initialize query_pathkeys and related pathkey lists before
calling query_planner. However, since query_planner didn't actually *do*
anything with those lists before they'd been made canonical, we can get rid
of the whole mess by just not creating the lists at all until the point
where we formerly canonicalized them.
There are several ways in which we could implement that without making
query_planner itself deal with grouping/sorting features (which are
supposed to be the province of grouping_planner). I chose to add a
callback function to query_planner's API; other alternatives would have
required adding more fields to PlannerInfo, which while not bad in itself
would create an ABI break for planner-related plugins in the 9.2 release
series. This still breaks ABI for anything that calls query_planner
directly, but it seems somewhat unlikely that there are any such plugins.
I had originally conceived of this change as merely a step on the way to
fixing bug #8049 from Teun Hoogendoorn; but it turns out that this fixes
that bug all by itself, as per the added regression test. The reason is
that now get_eclass_for_sort_expr is adding the ORDER BY expression at the
end of EquivalenceClass creation not the start, and so anything that is in
a multi-member EquivalenceClass has already been created with correct
em_nullable_relids. I am suspicious that there are related scenarios in
which we still need to teach get_eclass_for_sort_expr to compute correct
nullable_relids, but am not eager to risk destabilizing either 9.2 or 9.3
to fix bugs that are only hypothetical. So for the moment, do this and
stop here.
Back-patch to 9.2 but not to earlier branches, since they don't exhibit
this bug for lack of join-clause-movement logic that depends on
em_nullable_relids being correct. (We might have to revisit that choice
if any related bugs turn up.) In 9.2, don't change the signature of
make_pathkeys_for_sortclauses nor remove canonicalize_pathkeys, so as
not to risk more plugin breakage than we have to.
Move checking for unscannable matviews into ExecOpenScanRelation, which is
a better place for it first because the open relation is already available
(saving a relcache lookup cycle), and second because this eliminates the
problem of telling the difference between rangetable entries that will or
will not be scanned by the query. In particular we can get rid of the
not-terribly-well-thought-out-or-implemented isResultRel field that the
initial matviews patch added to RangeTblEntry.
Also get rid of entirely unnecessary scannability check in the rewriter,
and a bogus decision about whether RefreshMatViewStmt requires a parse-time
snapshot.
catversion bump due to removal of a RangeTblEntry field, which changes
stored rules.
In most cases, these were just references to the SQL standard in
general. In a few cases, a contrast was made between SQL92 and later
standards -- those have been kept unchanged.
Revert the matview-related changes in explain.c's API, as per recent
complaint from Robert Haas. The reason for these appears to have been
principally some ill-considered choices around having intorel_startup do
what ought to be parse-time checking, plus a poor arrangement for passing
it the view parsetree it needs to store into pg_rewrite when creating a
materialized view. Do the latter by having parse analysis stick a copy
into the IntoClause, instead of doing it at runtime. (On the whole,
I seriously question the choice to represent CREATE MATERIALIZED VIEW as a
variant of SELECT INTO/CREATE TABLE AS, because that means injecting even
more complexity into what was already a horrid legacy kluge. However,
I didn't go so far as to rethink that choice ... yet.)
I also moved several error checks into matview parse analysis, and
made the check for external Params in a matview more accurate.
In passing, clean things up a bit more around interpretOidsOption(),
and fix things so that we can use that to force no-oids for views,
sequences, etc, thereby eliminating the need to cons up "oids = false"
options when creating them.
catversion bump due to change in IntoClause. (I wonder though if we
really need readfuncs/outfuncs support for IntoClause anymore.)
This patch adds the core-system infrastructure needed to support updates
on foreign tables, and extends contrib/postgres_fdw to allow updates
against remote Postgres servers. There's still a great deal of room for
improvement in optimization of remote updates, but at least there's basic
functionality there now.
KaiGai Kohei, reviewed by Alexander Korotkov and Laurenz Albe, and rather
heavily revised by Tom Lane.
A materialized view has a rule just like a view and a heap and
other physical properties like a table. The rule is only used to
populate the table, references in queries refer to the
materialized data.
This is a minimal implementation, but should still be useful in
many cases. Currently data is only populated "on demand" by the
CREATE MATERIALIZED VIEW and REFRESH MATERIALIZED VIEW statements.
It is expected that future releases will add incremental updates
with various timings, and that a more refined concept of defining
what is "fresh" data will be developed. At some point it may even
be possible to have queries use a materialized in place of
references to underlying tables, but that requires the other
above-mentioned features to be working first.
Much of the documentation work by Robert Haas.
Review by Noah Misch, Thom Brown, Robert Haas, Marko Tiikkaja
Security review by KaiGai Kohei, with a decision on how best to
implement sepgsql still pending.
This includes backend "COPY TO/FROM PROGRAM '...'" syntax, and corresponding
psql \copy syntax. Like with reading/writing files, the backend version is
superuser-only, and in the psql version, the program is run in the client.
In the passing, the psql \copy STDIN/STDOUT syntax is subtly changed: if you
the stdin/stdout is quoted, it's now interpreted as a filename. For example,
"\copy foo from 'stdin'" now reads from a file called 'stdin', not from
standard input. Before this, there was no way to specify a filename called
stdin, stdout, pstdin or pstdout.
This creates a new function in pgport, wait_result_to_str(), which can
be used to convert the exit status of a process, as returned by wait(3),
to a human-readable string.
Etsuro Fujita, reviewed by Amit Kapila.
This patch introduces two additional lock modes for tuples: "SELECT FOR
KEY SHARE" and "SELECT FOR NO KEY UPDATE". These don't block each
other, in contrast with already existing "SELECT FOR SHARE" and "SELECT
FOR UPDATE". UPDATE commands that do not modify the values stored in
the columns that are part of the key of the tuple now grab a SELECT FOR
NO KEY UPDATE lock on the tuple, allowing them to proceed concurrently
with tuple locks of the FOR KEY SHARE variety.
Foreign key triggers now use FOR KEY SHARE instead of FOR SHARE; this
means the concurrency improvement applies to them, which is the whole
point of this patch.
The added tuple lock semantics require some rejiggering of the multixact
module, so that the locking level that each transaction is holding can
be stored alongside its Xid. Also, multixacts now need to persist
across server restarts and crashes, because they can now represent not
only tuple locks, but also tuple updates. This means we need more
careful tracking of lifetime of pg_multixact SLRU files; since they now
persist longer, we require more infrastructure to figure out when they
can be removed. pg_upgrade also needs to be careful to copy
pg_multixact files over from the old server to the new, or at least part
of multixact.c state, depending on the versions of the old and new
servers.
Tuple time qualification rules (HeapTupleSatisfies routines) need to be
careful not to consider tuples with the "is multi" infomask bit set as
being only locked; they might need to look up MultiXact values (i.e.
possibly do pg_multixact I/O) to find out the Xid that updated a tuple,
whereas they previously were assured to only use information readily
available from the tuple header. This is considered acceptable, because
the extra I/O would involve cases that would previously cause some
commands to block waiting for concurrent transactions to finish.
Another important change is the fact that locking tuples that have
previously been updated causes the future versions to be marked as
locked, too; this is essential for correctness of foreign key checks.
This causes additional WAL-logging, also (there was previously a single
WAL record for a locked tuple; now there are as many as updated copies
of the tuple there exist.)
With all this in place, contention related to tuples being checked by
foreign key rules should be much reduced.
As a bonus, the old behavior that a subtransaction grabbing a stronger
tuple lock than the parent (sub)transaction held on a given tuple and
later aborting caused the weaker lock to be lost, has been fixed.
Many new spec files were added for isolation tester framework, to ensure
overall behavior is sane. There's probably room for several more tests.
There were several reviewers of this patch; in particular, Noah Misch
and Andres Freund spent considerable time in it. Original idea for the
patch came from Simon Riggs, after a problem report by Joel Jacobson.
Most code is from me, with contributions from Marti Raudsepp, Alexander
Shulgin, Noah Misch and Andres Freund.
This patch was discussed in several pgsql-hackers threads; the most
important start at the following message-ids:
AANLkTimo9XVcEzfiBR-ut3KVNDkjm2Vxh+t8kAmWjPuv@mail.gmail.com1290721684-sup-3951@alvh.no-ip.org1294953201-sup-2099@alvh.no-ip.org1320343602-sup-2290@alvh.no-ip.org1339690386-sup-8927@alvh.no-ip.org4FE5FF020200002500048A3D@gw.wicourts.gov4FEAB90A0200002500048B7D@gw.wicourts.gov
Originally we didn't bother to mark FuncExprs with any indication whether
VARIADIC had been given in the source text, because there didn't seem to be
any need for it at runtime. However, because we cannot fold a VARIADIC ANY
function's arguments into an array (since they're not necessarily all the
same type), we do actually need that information at runtime if VARIADIC ANY
functions are to respond unsurprisingly to use of the VARIADIC keyword.
Add the missing field, and also fix ruleutils.c so that VARIADIC ANY
function calls are dumped properly.
Extracted from a larger patch that also fixes concat() and format() (the
only two extant VARIADIC ANY functions) to behave properly when VARIADIC is
specified. This portion seems appropriate to review and commit separately.
Pavel Stehule
Historically we've used a couple of very ad-hoc fudge factors to try to
get the right results when indexes of different sizes would satisfy a
query with the same number of index leaf tuples being visited. In
commit 21a39de580 I tweaked one of these
fudge factors, with results that proved disastrous for larger indexes.
Commit bf01e34b55 fudged it some more,
but still with not a lot of principle behind it.
What seems like a better way to address these issues is to explicitly model
index-descent costs, since that's what's really at stake when considering
diferent indexes with similar leaf-page-level costs. We tried that once
long ago, and found that charging random_page_cost per page descended
through was way too much, because upper btree levels tend to stay in cache
in real-world workloads. However, there's still CPU costs to think about,
and the previous fudge factors can be seen as a crude attempt to account
for those costs. So this patch replaces those fudge factors with explicit
charges for the number of tuple comparisons needed to descend the index
tree, plus a small charge per page touched in the descent. The cost
multipliers are chosen so that the resulting charges are in the vicinity of
the historical (pre-9.2) fudge factors for indexes of up to about a million
tuples, while not ballooning unreasonably beyond that, as the old fudge
factor did (even more so in 9.2).
To make this work accurately for btree indexes, add some code that allows
extraction of the known root-page height from a btree. There's no
equivalent number readily available for other index types, but we can use
the log of the number of index pages as an approximate substitute.
This seems like too much of a behavioral change to risk back-patching,
but it should improve matters going forward. In 9.2 I'll just revert
the fudge-factor change.
transformExpr() is required to cope with already-transformed expression
trees, for various ugly-but-not-quite-worth-cleaning-up reasons. However,
some of its newer subroutines hadn't gotten the memo. This accounts for
bug #7763 from Norbert Buchmuller: transformRowExpr() was overwriting the
previously determined type of a RowExpr during CREATE TABLE LIKE INCLUDING
INDEXES. Additional investigation showed that transformXmlExpr had the
same kind of problem, but all the other cases seem to be safe.
Andres Freund and Tom Lane
Before this patch, streaming replication would refuse to start replicating
if the timeline in the primary doesn't exactly match the standby. The
situation where it doesn't match is when you have a master, and two
standbys, and you promote one of the standbys to become new master.
Promoting bumps up the timeline ID, and after that bump, the other standby
would refuse to continue.
There's significantly more timeline related logic in streaming replication
now. First of all, when a standby connects to primary, it will ask the
primary for any timeline history files that are missing from the standby.
The missing files are sent using a new replication command TIMELINE_HISTORY,
and stored in standby's pg_xlog directory. Using the timeline history files,
the standby can follow the latest timeline present in the primary
(recovery_target_timeline='latest'), just as it can follow new timelines
appearing in an archive directory.
START_REPLICATION now takes a TIMELINE parameter, to specify exactly which
timeline to stream WAL from. This allows the standby to request the primary
to send over WAL that precedes the promotion. The replication protocol is
changed slightly (in a backwards-compatible way although there's little hope
of streaming replication working across major versions anyway), to allow
replication to stop when the end of timeline reached, putting the walsender
back into accepting a replication command.
Many thanks to Amit Kapila for testing and reviewing various versions of
this patch.
There are probably other places where this can be used, but for now,
this just makes MergeAppend use it, so that this code will have test
coverage. There is other work in the queue that will use this, as
well.
Abhijit Menon-Sen, reviewed by Andres Freund, Robert Haas, Álvaro
Herrera, Tom Lane, and others.
This case got broken in 8.4 by the addition of an error check that
complains if ALTER TABLE ONLY is used on a table that has children.
We do use ONLY for this situation, but it's okay because the necessary
recursion occurs at a higher level. So we need to have a separate
flag to suppress recursion without making the error check.
Reported and patched by Pavan Deolasee, with some editorial adjustments by
me. Back-patch to 8.4, since this is a regression of functionality that
worked in earlier branches.
If a potential equivalence clause references a variable from the nullable
side of an outer join, the planner needs to take care that derived clauses
are not pushed to below the outer join; else they may use the wrong value
for the variable. (The problem arises only with non-strict clauses, since
if an upper clause can be proven strict then the outer join will get
simplified to a plain join.) The planner attempted to prevent this type
of error by checking that potential equivalence clauses aren't
outerjoin-delayed as a whole, but actually we have to check each side
separately, since the two sides of the clause will get moved around
separately if it's treated as an equivalence. Bugs of this type can be
demonstrated as far back as 7.4, even though releases before 8.3 had only
a very ad-hoc notion of equivalence clauses.
In addition, we neglected to account for the possibility that such clauses
might have nonempty nullable_relids even when not outerjoin-delayed; so the
equivalence-class machinery lacked logic to compute correct nullable_relids
values for clauses it constructs. This oversight was harmless before 9.2
because we were only using RestrictInfo.nullable_relids for OR clauses;
but as of 9.2 it could result in pushing constructed equivalence clauses
to incorrect places. (This accounts for bug #7604 from Bill MacArthur.)
Fix the first problem by adding a new test check_equivalence_delay() in
distribute_qual_to_rels, and fix the second one by adding code in
equivclass.c and called functions to set correct nullable_relids for
generated clauses. Although I believe the second part of this is not
currently necessary before 9.2, I chose to back-patch it anyway, partly to
keep the logic similar across branches and partly because it seems possible
we might find other reasons why we need valid values of nullable_relids in
the older branches.
Add regression tests illustrating these problems. In 9.0 and up, also
add test cases checking that we can push constants through outer joins,
since we've broken that optimization before and I nearly broke it again
with an overly simplistic patch for this problem.
This change ensures that the planner will see implicit and explicit casts
as equivalent for all purposes, except in the minority of cases where
there's actually a semantic difference (as reflected by having a 3-argument
cast function). In particular, this fixes cases where the EquivalenceClass
machinery failed to consider two references to a varchar column as
equivalent if one was implicitly cast to text but the other was explicitly
cast to text, as seen in bug #7598 from Vaclav Juza. We have had similar
bugs before in other parts of the planner, so I think it's time to fix this
problem at the core instead of continuing to band-aid around it.
Remove set_coercionform_dontcare(), which represents the band-aid
previously in use for allowing matching of index and constraint expressions
with inconsistent cast labeling. (We can probably get rid of
COERCE_DONTCARE altogether, but I don't think removing that enum value in
back branches would be wise; it's possible there's third party code
referring to it.)
Back-patch to 9.2. We could go back further, and might want to once this
has been tested more; but for the moment I won't risk destabilizing plan
choices in long-since-stable branches.
The former name was too likely to conflict with symbols from external
headers; and, as seen in recent buildfarm failures in member spoonbill,
it has now happened at least in plpython.
We already had those, but they forced modules to spell out the function
bodies twice. Eliminate some duplicates we had already grown.
Extracted from a somewhat larger patch from Andres Freund.
Per discussion, schema-element subcommands are not allowed together with
this option, since it's not very obvious what should happen to the element
objects.
Fabrízio de Royes Mello
Remove duplicate implementation of catalog munging and miscellaneous
privilege and consistency checks. Instead rely on already existing data
in objectaddress.c to do the work.
Author: KaiGai Kohei
Tweaked by me
Reviewed by Robert Haas
Instead of having each object type implement the catalog munging
independently, centralize knowledge about how to do it and expand the
existing table in objectaddress.c with enough data about each object
type to support this operation.
Author: KaiGai Kohei
Tweaks by me
Reviewed by Robert Haas
Produce a NOTICE when the label already exists, for consistency with other
CREATE IF NOT EXISTS commands. Also, fix the code so it produces something
more user-friendly than an index violation when the label already exists.
This not incidentally enables making a regression test that the previous
patch didn't make for fear of exposing an unpredictable OID in the results.
Also some wordsmithing on the documentation.
If the label is already in the enum the statement becomes a no-op.
This will reduce the pain that comes from our not allowing this
operation inside a transaction block.
Andrew Dunstan, reviewed by Tom Lane and Magnus Hagander.
The planner previously assumed that parameter Vars having the same absolute
query level, varno, and varattno could safely be assigned the same runtime
PARAM_EXEC slot, even though they might be different Vars appearing in
different subqueries. This was (probably) safe before the introduction of
CTEs, but the lazy-evalution mechanism used for CTEs means that a CTE can
be executed during execution of some other subquery, causing the lifespan
of Params at the same syntactic nesting level as the CTE to overlap with
use of the same slots inside the CTE. In 9.1 we created additional hazards
by using the same parameter-assignment technology for nestloop inner scan
parameters, but it was broken before that, as illustrated by the added
regression test.
To fix, restructure the planner's management of PlannerParamItems so that
items having different semantic lifespans are kept rigorously separated.
This will probably result in complex queries using more runtime PARAM_EXEC
slots than before, but the slots are cheap enough that this hardly matters.
Also, stop generating PlannerParamItems containing Params for subquery
outputs: all we really need to do is reserve the PARAM_EXEC slot number,
and that now only takes incrementing a counter. The planning code is
simpler and probably faster than before, as well as being more correct.
Per report from Vik Reykja.
These changes will mostly also need to be made in the back branches, but
I'm going to hold off on that until after 9.2.0 wraps.
We can detect whether the planner top level is going to care at all about
cheap startup cost (it will only do so if query_planner's tuple_fraction
argument is greater than zero). If it isn't, we might as well discard
paths immediately whose only advantage over others is cheap startup cost.
This turns out to get rid of quite a lot of paths in complex queries ---
I saw planner runtime reduction of more than a third on one large query.
Since add_path isn't currently passed the PlannerInfo "root", the easiest
way to tell it whether to do this was to add a bool flag to RelOptInfo.
That's a bit redundant, since all relations in a given query level will
have the same setting. But in the future it's possible that we'd refine
the control decision to work on a per-relation basis, so this seems like
a good arrangement anyway.
Per my suggestion of a few months ago.
In the initial cut at LATERAL, I kept the rule that cheapest_total_path
was always unparameterized, which meant it had to be NULL if the relation
has no unparameterized paths. It turns out to work much more nicely if
we always have *some* path nominated as cheapest-total for each relation.
In particular, let's still say it's the cheapest unparameterized path if
there is one; if not, take the cheapest-total-cost path among those of
the minimum available parameterization. (The first rule is actually
a special case of the second.)
This allows reversion of some temporary lobotomizations I'd put in place.
In particular, the planner can now consider hash and merge joins for
joins below a parameter-supplying nestloop, even if there aren't any
unparameterized paths available. This should bring planning of
LATERAL-containing queries to the same level as queries not using that
feature.
Along the way, simplify management of parameterized paths in add_path()
and friends. In the original coding for parameterized paths in 9.2,
I tried to minimize the logic changes in add_path(), so it just treated
parameterization as yet another dimension of comparison for paths.
We later made it ignore pathkeys (sort ordering) of parameterized paths,
on the grounds that ordering isn't a useful property for the path on the
inside of a nestloop, so we might as well get rid of useless parameterized
paths as quickly as possible. But we didn't take that reasoning as far as
we should have. Startup cost isn't a useful property inside a nestloop
either, so add_path() ought to discount startup cost of parameterized paths
as well. Having done that, the secondary sorting I'd implemented (in
add_parameterized_path) is no longer needed --- any parameterized path that
survives add_path() at all is worth considering at higher levels. So this
should be a bit faster as well as simpler.
This patch takes care of a number of problems having to do with failure
to choose valid join orders and incorrect handling of lateral references
pulled up from subqueries. Notable changes:
* Add a LateralJoinInfo data structure similar to SpecialJoinInfo, to
represent join ordering constraints created by lateral references.
(I first considered extending the SpecialJoinInfo structure, but the
semantics are different enough that a separate data structure seems
better.) Extend join_is_legal() and related functions to prevent trying
to form unworkable joins, and to ensure that we will consider joins that
satisfy lateral references even if the joins would be clauseless.
* Fill in the infrastructure needed for the last few types of relation scan
paths to support parameterization. We'd have wanted this eventually
anyway, but it is necessary now because a relation that gets pulled up out
of a UNION ALL subquery may acquire a reltargetlist containing lateral
references, meaning that its paths *have* to be parameterized whether or
not we have any code that can push join quals down into the scan.
* Compute data about lateral references early in query_planner(), and save
in RelOptInfo nodes, to avoid repetitive calculations later.
* Assorted corner-case bug fixes.
There's probably still some bugs left, but this is a lot closer to being
real than it was before.
This patch implements the standard syntax of LATERAL attached to a
sub-SELECT in FROM, and also allows LATERAL attached to a function in FROM,
since set-returning function calls are expected to be one of the principal
use-cases.
The main change here is a rewrite of the mechanism for keeping track of
which relations are visible for column references while the FROM clause is
being scanned. The parser "namespace" lists are no longer lists of bare
RTEs, but are lists of ParseNamespaceItem structs, which carry an RTE
pointer as well as some visibility-controlling flags. Aside from
supporting LATERAL correctly, this lets us get rid of the ancient hacks
that required rechecking subqueries and JOIN/ON and function-in-FROM
expressions for invalid references after they were initially parsed.
Invalid column references are now always correctly detected on sight.
In passing, remove assorted parser error checks that are now dead code by
virtue of our having gotten rid of add_missing_from, as well as some
comments that are obsolete for the same reason. (It was mainly
add_missing_from that caused so much fudging here in the first place.)
The planner support for this feature is very minimal, and will be improved
in future patches. It works well enough for testing purposes, though.
catversion bump forced due to new field in RangeTblEntry.
Parse analysis neglected to cover the case of a WITH clause attached to an
intermediate-level set operation; it only handled WITH at the top level
or WITH attached to a leaf-level SELECT. Per report from Adam Mackler.
In HEAD, I rearranged the order of SelectStmt's fields to put withClause
with the other fields that can appear on non-leaf SelectStmts. In back
branches, leave it alone to avoid a possible ABI break for third-party
code.
Back-patch to 8.4 where WITH support was added.
When a whole-row Var is reading the result of a subquery, we need it to
ignore any "resjunk" columns that the subquery might have evaluated for
GROUP BY or ORDER BY purposes. We've hacked this area before, in commit
68e40998d0, but that fix only covered
whole-row Vars of named composite types, not those of RECORD type; and it
was mighty klugy anyway, since it just assumed without checking that any
extra columns in the result must be resjunk. A proper fix requires getting
hold of the subquery's targetlist so we can actually see which columns are
resjunk (whereupon we can use a JunkFilter to get rid of them). So bite
the bullet and add some infrastructure to make that possible.
Per report from Andrew Dunstan and additional testing by Merlin Moncure.
Back-patch to all supported branches. In 8.3, also back-patch commit
292176a118, which for some reason I had
not done at the time, but it's a prerequisite for this change.
Commit 3855968f32 added syntax, pg_dump,
psql support, and documentation, but the triggers didn't actually fire.
With this commit, they now do. This is still a pretty basic facility
overall because event triggers do not get a whole lot of information
about what the user is trying to do unless you write them in C; and
there's still no option to fire them anywhere except at the very
beginning of the execution sequence, but it's better than nothing,
and a good building block for future work.
Along the way, add a regression test for ALTER LARGE OBJECT, since
testing of event triggers reveals that we haven't got one.
Dimitri Fontaine and Robert Haas
They don't actually do anything yet; that will get fixed in a
follow-on commit. But this gets the basic infrastructure in place,
including CREATE/ALTER/DROP EVENT TRIGGER; support for COMMENT,
SECURITY LABEL, and ALTER EXTENSION .. ADD/DROP EVENT TRIGGER;
pg_dump and psql support; and documentation for the anticipated
initial feature set.
Dimitri Fontaine, with review and a bunch of additional hacking by me.
Thom Brown extensively reviewed earlier versions of this patch set,
but there's not a whole lot of that code left in this commit, as it
turns out.
Formerly, when trying to copy both indexes and comments, CREATE TABLE LIKE
had to pre-assign names to indexes that had comments, because it made up an
explicit CommentStmt command to apply the comment and so it had to know the
name for the index. This creates bad interactions with other indexes, as
shown in bug #6734 from Daniele Varrazzo: the preassignment logic couldn't
take any other indexes into account so it could choose a conflicting name.
To fix, add a field to IndexStmt that allows it to carry a comment to be
assigned to the new index. (This isn't a user-exposed feature of CREATE
INDEX, only an internal option.) Now we don't need preassignment of index
names in any situation.
I also took the opportunity to refactor DefineIndex to accept the IndexStmt
as such, rather than passing all its fields individually in a mile-long
parameter list.
Back-patch to 9.2, but no further, because it seems too dangerous to change
IndexStmt or DefineIndex's API in released branches. The bug exists back
to 9.0 where CREATE TABLE LIKE grew the ability to copy comments, but given
the lack of prior complaints we'll just let it go unfixed before 9.2.
Repeated execution of an uncorrelated ARRAY_SUBLINK sub-select (which
I think can only happen if the sub-select is embedded in a larger,
correlated subquery) would leak memory for the duration of the query,
due to not reclaiming the array generated in the previous execution.
Per bug #6698 from Armando Miraglia. Diagnosis and fix idea by Heikki,
patch itself by me.
This has been like this all along, so back-patch to all supported versions.
Previously we followed the SQL92 wording, "MATCH <unspecified>", but since
SQL99 there's been a less awkward way to refer to the default style.
In addition to the code changes, pg_constraint.confmatchtype now stores
this match style as 's' (SIMPLE) rather than 'u' (UNSPECIFIED). This
doesn't affect pg_dump or psql because they use pg_get_constraintdef()
to reconstruct foreign key definitions. But other client-side code might
examine that column directly, so this change will have to be marked as
an incompatibility in the 9.3 release notes.
The original syntax wasn't universally loved, and it didn't allow its
usage in CREATE TABLE, only ALTER TABLE. It now works everywhere, and
it also allows using ALTER TABLE ONLY to add an uninherited CHECK
constraint, per discussion.
The pg_constraint column has accordingly been renamed connoinherit.
This commit partly reverts some of the changes in
61d81bd28d, particularly some pg_dump and
psql bits, because now pg_get_constraintdef includes the necessary NO
INHERIT within the constraint definition.
Author: Nikhil Sontakke
Some tweaks by me
This patch adjusts the treatment of parameterized paths so that all paths
with the same parameterization (same set of required outer rels) for the
same relation will have the same rowcount estimate. We cache the rowcount
estimates to ensure that property, and hopefully save a few cycles too.
Doing this makes it practical for add_path_precheck to operate without
a rowcount estimate: it need only assume that paths with different
parameterizations never dominate each other, which is close enough to
true anyway for coarse filtering, because normally a more-parameterized
path should yield fewer rows thanks to having more join clauses to apply.
In add_path, we do the full nine yards of comparing rowcount estimates
along with everything else, so that we can discard parameterized paths that
don't actually have an advantage. This fixes some issues I'd found with
add_path rejecting parameterized paths on the grounds that they were more
expensive than not-parameterized ones, even though they yielded many fewer
rows and hence would be cheaper once subsequent joining was considered.
To make the same-rowcounts assumption valid, we have to require that any
parameterized path enforce *all* join clauses that could be obtained from
the particular set of outer rels, even if not all of them are useful for
indexing. This is required at both base scans and joins. It's a good
thing anyway since the net impact is that join quals are checked at the
lowest practical level in the join tree. Hence, discard the original
rather ad-hoc mechanism for choosing parameterization joinquals, and build
a better one that has a more principled rule for when clauses can be moved.
The original rule was actually buggy anyway for lack of knowledge about
which relations are part of an outer join's outer side; getting this right
requires adding an outer_relids field to RestrictInfo.
Add a queryId field to Query and PlannedStmt. This is not used by the
core backend, except for being copied around at appropriate times.
It's meant to allow plug-ins to track a particular query forward from
parse analysis to execution.
The queryId is intentionally not dumped into stored rules (and hence this
commit doesn't bump catversion). You could argue that choice either way,
but it seems better that stored rule strings not have any dependency
on plug-ins that might or might not be present.
Also, add a post_parse_analyze_hook that gets invoked at the end of
parse analysis (but only for top-level analysis of complete queries,
not cases such as analyzing a domain's default-value expression).
This is mainly meant to be used to compute and assign a queryId,
but it could have other applications.
Peter Geoghegan
For some reason, in the original coding of the PlaceHolderVar mechanism
I had supposed that PlaceHolderVars couldn't propagate into subqueries.
That is of course entirely possible. When it happens, we need to treat
an outer-level PlaceHolderVar much like an outer Var or Aggref, that is
SS_replace_correlation_vars() needs to replace the PlaceHolderVar with
a Param, and then when building the finished SubPlan we have to provide
the PlaceHolderVar expression as an actual parameter for the SubPlan.
The handling of the contained expression is a bit delicate but it can be
treated exactly like an Aggref's expression.
In addition to the missing logic in subselect.c, prepjointree.c was failing
to search subqueries for PlaceHolderVars that need their relids adjusted
during subquery pullup. It looks like everyplace else that touches
PlaceHolderVars got it right, though.
Per report from Mark Murawski. In 9.1 and HEAD, queries affected by this
oversight would fail with "ERROR: Upper-level PlaceHolderVar found where
not expected". But in 9.0 and 8.4, you'd silently get possibly-wrong
answers, since the value transmitted into the subquery wouldn't go to null
when it should.
Fix loss of previous expression-simplification work when a transform
function fires: we must not simply revert to untransformed input tree.
Instead build a dummy FuncExpr node to pass to the transform function.
This has the additional advantage of providing a simpler, more uniform
API for transform functions.
Move documentation to a somewhat less buried spot, relocate some
poorly-placed code, be more wary of null constants and invalid typmod
values, add an opr_sanity check on protransform function signatures,
and some other minor cosmetic adjustments.
Note: although this patch touches pg_proc.h, no need for catversion
bump, because the changes are cosmetic and don't actually change the
intended catalog contents.
Making this operation look like a utility statement seems generally a good
idea, and particularly so in light of the desire to provide command
triggers for utility statements. The original choice of representing it as
SELECT with an IntoClause appendage had metastasized into rather a lot of
places, unfortunately, so that this patch is a great deal more complicated
than one might at first expect.
In particular, keeping EXPLAIN working for SELECT INTO and CREATE TABLE AS
subcommands required restructuring some EXPLAIN-related APIs. Add-on code
that calls ExplainOnePlan or ExplainOneUtility, or uses
ExplainOneQuery_hook, will need adjustment.
Also, the cases PREPARE ... SELECT INTO and CREATE RULE ... SELECT INTO,
which formerly were accepted though undocumented, are no longer accepted.
The PREPARE case can be replaced with use of CREATE TABLE AS EXECUTE.
The CREATE RULE case doesn't seem to have much real-world use (since the
rule would work only once before failing with "table already exists"),
so we'll not bother with that one.
Both SELECT INTO and CREATE TABLE AS still return a command tag of
"SELECT nnnn". There was some discussion of returning "CREATE TABLE nnnn",
but for the moment backwards compatibility wins the day.
Andres Freund and Tom Lane
In commit 57664ed25e I tried to fix a bug
reported by Teodor Sigaev by making non-simple-Var output columns distinct
(by wrapping their expressions with dummy PlaceHolderVar nodes). This did
not work too well. Commit b28ffd0fcc fixed
some ensuing problems with matching to child indexes, but per a recent
report from Claus Stadler, constraint exclusion of UNION ALL subqueries was
still broken, because constant-simplification didn't handle the injected
PlaceHolderVars well either. On reflection, the original patch was quite
misguided: there is no reason to expect that EquivalenceClass child members
will be distinct. So instead of trying to make them so, we should ensure
that we can cope with the situation when they're not.
Accordingly, this patch reverts the code changes in the above-mentioned
commits (though the regression test cases they added stay). Instead, I've
added assorted defenses to make sure that duplicate EC child members don't
cause any problems. Teodor's original problem ("MergeAppend child's
targetlist doesn't match MergeAppend") is addressed more directly by
revising prepare_sort_from_pathkeys to let the parent MergeAppend's sort
list guide creation of each child's sort list.
In passing, get rid of add_sort_column; as far as I can tell, testing for
duplicate sort keys at this stage is dead code. Certainly it doesn't
trigger often enough to be worth expending cycles on in ordinary queries.
And keeping the test would've greatly complicated the new logic in
prepare_sort_from_pathkeys, because comparing pathkey list entries against
a previous output array requires that we not skip any entries in the list.
Back-patch to 9.1, like the previous patches. The only known issue in
this area that wasn't caused by the ill-advised previous patches was the
MergeAppend planning failure, which of course is not relevant before 9.1.
It's possible that we need some of the new defenses against duplicate child
EC entries in older branches, but until there's some clear evidence of that
I'm going to refrain from back-patching further.
Further reflection shows that a single callback isn't very workable if we
desire to let FDWs generate multiple Paths, because that forces the FDW to
do all work necessary to generate a valid Plan node for each Path. Instead
split the former PlanForeignScan API into three steps: GetForeignRelSize,
GetForeignPaths, GetForeignPlan. We had already bit the bullet of breaking
the 9.1 FDW API for 9.2, so this shouldn't cause very much additional pain,
and it's substantially more flexible for complex FDWs.
Add an fdw_private field to RelOptInfo so that the new functions can save
state there rather than possibly having to recalculate information two or
three times.
In addition, we'd not thought through what would be needed to allow an FDW
to set up subexpressions of its choice for runtime execution. We could
treat ForeignScan.fdw_private as an executable expression but that seems
likely to break existing FDWs unnecessarily (in particular, it would
restrict the set of node types allowable in fdw_private to those supported
by expression_tree_walker). Instead, invent a separate field fdw_exprs
which will receive the postprocessing appropriate for expression trees.
(One field is enough since it can be a list of expressions; also, we assume
the corresponding expression state tree(s) will be held within fdw_state,
so we don't need to add anything to ForeignScanState.)
Per review of Hanada Shigeru's pgsql_fdw patch. We may need to tweak this
further as we continue to work on that patch, but to me it feels a lot
closer to being right now.
The original API specification only allowed an FDW to create a single
access path, which doesn't seem like a terribly good idea in hindsight.
Instead, move the responsibility for building the Path node and calling
add_path() into the FDW's PlanForeignScan function. Now, it can do that
more than once if appropriate. There is no longer any need for the
transient FdwPlan struct, so get rid of that.
Etsuro Fujita, Shigeru Hanada, Tom Lane
We already skip rewriting the table in these cases, but we still force a
whole table scan to validate the data. This can be skipped, and thus
we can make the whole ALTER TABLE operation just do some catalog touches
instead of scanning the table, when these two conditions hold:
(a) Old and new pg_constraint.conpfeqop match exactly. This is actually
stronger than needed; we could loosen things by way of operator
families, but it'd require a lot more effort.
(b) The functions, if any, implementing a cast from the foreign type to
the primary opcintype are the same. For this purpose, we can consider a
binary coercion equivalent to an exact type match. When the opcintype
is polymorphic, require that the old and new foreign types match
exactly. (Since ri_triggers.c does use the executor, the stronger check
for polymorphic types is no mere future-proofing. However, no core type
exercises its necessity.)
Author: Noah Misch
Committer's note: catalog version bumped due to change of the Constraint
node. I can't actually find any way to have such a node in a stored
rule, but given that we have "out" support for them, better be safe.
The hstore and json datatypes both have record-conversion functions that
pay attention to column names in the composite values they're handed.
We used to not worry about inserting correct field names into tuple
descriptors generated at runtime, but given these examples it seems
useful to do so. Observe the nicer-looking results in the regression
tests whose results changed.
catversion bump because there is a subtle change in requirements for stored
rule parsetrees: RowExprs from ROW() constructs now have to include field
names.
Andrew Dunstan and Tom Lane
This patch fixes the planner so that it can generate nestloop-with-
inner-indexscan plans even with one or more levels of joining between
the indexscan and the nestloop join that is supplying the parameter.
The executor was fixed to handle such cases some time ago, but the
planner was not ready. This should improve our plans in many situations
where join ordering restrictions formerly forced complete table scans.
There is probably a fair amount of tuning work yet to be done, because
of various heuristics that have been added to limit the number of
parameterized paths considered. However, we are not going to find out
what needs to be adjusted until the code gets some real-world use, so
it's time to get it in there where it can be tested easily.
Note API change for index AM amcostestimate functions. I'm not aware of
any non-core index AMs, but if there are any, they will need minor
adjustments.
The original implementation of this interpreted it as a kind of
"inheritance" facility and named all the internal structures
accordingly. This turned out to be very confusing, because it has
nothing to do with the INHERITS feature. So rename all the internal
parser infrastructure, update the comments, adjust the error messages,
and split up the regression tests.
ALTER DOMAIN / DROP CONSTRAINT on a nonexistent constraint name did
not report any error. Now it reports an error. The IF EXISTS option
was added to get the usual behavior of ignoring nonexistent objects to
drop.
In commit e2c2c2e8b1 I made use of nested
list structures to show which clauses went with which index columns, but
on reflection that's a data structure that only an old-line Lisp hacker
could love. Worse, it adds unnecessary complication to the many places
that don't much care which clauses go with which index columns. Revert
to the previous arrangement of flat lists of clauses, and instead add a
parallel integer list of column numbers. The places that care about the
pairing can chase both lists with forboth(), while the places that don't
care just examine one list the same as before.
The only real downside to this is that there are now two more lists that
need to be passed to amcostestimate functions in case they care about
column matching (which btcostestimate does, so not passing the info is not
an option). Rather than deal with 11-argument amcostestimate functions,
pass just the IndexPath and expect the functions to extract fields from it.
That gets us down to 7 arguments which is better than 11, and it seems
more future-proof against likely additions to the information we keep
about an index path.
It's potentially useful for an index to repeat the same indexable column
or expression in multiple index columns, if the columns have different
opclasses. (If they share opclasses too, the duplicate column is pretty
useless, but nonetheless we've allowed such cases since 9.0.) However,
the planner failed to cope with this, because createplan.c was relying on
simple equal() matching to figure out which index column each index qual
is intended for. We do have that information available upstream in
indxpath.c, though, so the fix is to not flatten the multi-level indexquals
list when putting it into an IndexPath. Then we can rely on the sublist
structure to identify target index columns in createplan.c. There's a
similar issue for index ORDER BYs (the KNNGIST feature), so introduce a
multi-level-list representation for that too. This adds a bit more
representational overhead, but we might more or less buy that back by not
having to search for matching index columns anymore in createplan.c;
likewise btcostestimate saves some cycles.
Per bug #6351 from Christian Rudolph. Likely symptoms include the "btree
index keys must be ordered by attribute" failure shown there, as well as
"operator MMMM is not a member of opfamily NNNN".
Although this is a pre-existing problem that can be demonstrated in 9.0 and
9.1, I'm not going to back-patch it, because the API changes in the planner
seem likely to break things such as index plugins. The corner cases where
this matters seem too narrow to justify possibly breaking things in a minor
release.
When a view is marked as a security barrier, it will not be pulled up
into the containing query, and no quals will be pushed down into it,
so that no function or operator chosen by the user can be applied to
rows not exposed by the view. Views not configured with this
option cannot provide robust row-level security, but will perform far
better.
Patch by KaiGai Kohei; original problem report by Heikki Linnakangas
(in October 2009!). Review (in earlier versions) by Noah Misch and
others. Design advice by Tom Lane and myself. Further review and
cleanup by me.
This adds support for the more or less SQL-conforming USAGE privilege
on types and domains. The intent is to be able restrict which users
can create dependencies on types, which restricts the way in which
owners can alter types.
reviewed by Yeb Havinga
The need for this was debated when we put in the index-only-scan feature,
but at the time we had no near-term expectation of having AMs that could
support such scans for only some indexes; so we kept it simple. However,
the SP-GiST AM forces the issue, so let's fix it.
This patch only installs the new API; no behavior actually changes.
This patch creates an API whereby a btree index opclass can optionally
provide non-SQL-callable support functions for sorting. In the initial
patch, we only use this to provide a directly-callable comparator function,
which can be invoked with a bit less overhead than the traditional
SQL-callable comparator. While that should be of value in itself, the real
reason for doing this is to provide a datatype-extensible framework for
more aggressive optimizations, as in Peter Geoghegan's recent work.
Robert Haas and Tom Lane
The EvalPlanQual machinery assumes that whole-row Vars generated for the
outputs of non-table RTEs will be of composite types. However, for the
case where the RTE is a function call returning a scalar type, we were
doing the wrong thing, as a result of sharing code with a parser case
where the function's scalar output is wanted. (Or at least, that's what
that case has done historically; it does seem a bit inconsistent.)
To fix, extend makeWholeRowVar's API so that it can support both use-cases.
This fixes Belinda Cussen's report of crashes during concurrent execution
of UPDATEs involving joins to the result of UNNEST() --- in READ COMMITTED
mode, we'd run the EvalPlanQual machinery after a conflicting row update
commits, and it was expecting to get a HeapTuple not a scalar datum from
the "wholerowN" variable referencing the function RTE.
Back-patch to 9.0 where the current EvalPlanQual implementation appeared.
In 9.1 and up, this patch also fixes failure to attach the correct
collation to the Var generated for a scalar-result case. An example:
regression=# select upper(x.*) from textcat('ab', 'cd') x;
ERROR: could not determine which collation to use for upper() function
The WITH [NO] DATA option was not supported, nor the ability to specify
replacement column names; the former limitation wasn't even documented, as
per recent complaint from Naoya Anzai. Fix by moving the responsibility
for supporting these options into the executor. It actually takes less
code this way ...
catversion bump due to change in representation of IntoClause, which might
affect stored rules.
This gets rid of an impressive amount of duplicative code, with only
minimal behavior changes. DROP FOREIGN DATA WRAPPER now requires object
ownership rather than superuser privileges, matching the documentation
we already have. We also eliminate the historical warning about dropping
a built-in function as unuseful. All operations are now performed in the
same order for all object types handled by dropcmds.c.
KaiGai Kohei, with minor revisions by me
If we use a PlaceHolderVar from the outer relation in an inner indexscan,
we need to reference the PlaceHolderVar as such as the value to be passed
in from the outer relation. The previous code effectively tried to
reconstruct the PHV from its component expression, which doesn't work since
(a) the Vars therein aren't necessarily bubbled up far enough, and (b) it
would be the wrong semantics anyway because of the possibility that the PHV
is supposed to have gone to null at some point before the current join.
Point (a) led to "variable not found in subplan target list" planner
errors, but point (b) would have led to silently wrong answers.
Per report from Roger Niederland.
The uniqueness condition might fail to hold intra-transaction, and assuming
it does can give incorrect query results. Per report from Marti Raudsepp,
though this is not his proposed patch.
Back-patch to 9.0, where both these features were introduced. In the
released branches, add the new IndexOptInfo field to the end of the struct,
to try to minimize ABI breakage for third-party code that may be examining
that struct.
Add a column pg_class.relallvisible to remember the number of pages that
were all-visible according to the visibility map as of the last VACUUM
(or ANALYZE, or some other operations that update pg_class.relpages).
Use relallvisible/relpages, instead of an arbitrary constant, to estimate
how many heap page fetches can be avoided during an index-only scan.
This is pretty primitive and will no doubt see refinements once we've
acquired more field experience with the index-only scan mechanism, but
it's way better than using a constant.
Note: I had to adjust an underspecified query in the window.sql regression
test, because it was changing answers when the plan changed to use an
index-only scan. Some of the adjacent tests perhaps should be adjusted
as well, but I didn't do that here.
This commit changes index-only scans so that data is read directly from the
index tuple without first generating a faux heap tuple. The only immediate
benefit is that indexes on system columns (such as OID) can be used in
index-only scans, but this is necessary infrastructure if we are ever to
support index-only scans on expression indexes. The executor is now ready
for that, though the planner still needs substantial work to recognize
the possibility.
To do this, Vars in index-only plan nodes have to refer to index columns
not heap columns. I introduced a new special varno, INDEX_VAR, to mark
such Vars to avoid confusion. (In passing, this commit renames the two
existing special varnos to OUTER_VAR and INNER_VAR.) This allows
ruleutils.c to handle them with logic similar to what we use for subplan
reference Vars.
Since index-only scans are now fundamentally different from regular
indexscans so far as their expression subtrees are concerned, I also chose
to change them to have their own plan node type (and hence, their own
executor source file).
When a btree index contains all columns required by the query, and the
visibility map shows that all tuples on a target heap page are
visible-to-all, we don't need to fetch that heap page. This patch depends
on the previous patches that made the visibility map reliable.
There's a fair amount left to do here, notably trying to figure out a less
chintzy way of estimating the cost of an index-only scan, but the core
functionality seems ready to commit.
Robert Haas and Ibrar Ahmed, with some previous work by Heikki Linnakangas.
This provides information about the numbers of tuples that were visited
but not returned by table scans, as well as the numbers of join tuples
that were considered and discarded within a join plan node.
There is still some discussion going on about the best way to report counts
for outer-join situations, but I think most of what's in the patch would
not change if we revise that, so I'm going to go ahead and commit it as-is.
Documentation changes to follow (they weren't in the submitted patch
either).
Marko Tiikkaja, reviewed by Marc Cousin, somewhat revised by Tom
Rewrite plancache.c so that a "cached plan" (which is rather a misnomer
at this point) can support generation of custom, parameter-value-dependent
plans, and can make an intelligent choice between using custom plans and
the traditional generic-plan approach. The specific choice algorithm
implemented here can probably be improved in future, but this commit is
all about getting the mechanism in place, not the policy.
In addition, restructure the API to greatly reduce the amount of extraneous
data copying needed. The main compromise needed to make that possible was
to split the initial creation of a CachedPlanSource into two steps. It's
worth noting in particular that SPI_saveplan is now deprecated in favor of
SPI_keepplan, which accomplishes the same end result with zero data
copying, and no need to then spend even more cycles throwing away the
original SPIPlan. The risk of long-term memory leaks while manipulating
SPIPlans has also been greatly reduced. Most of this improvement is based
on use of the recently-added MemoryContextSetParent primitive.
This addresses only those cases that are easy to fix by adding or
moving a const qualifier or removing an unnecessary cast. There are
many more complicated cases remaining.
Formerly, set_subquery_pathlist and other creators of plans for subqueries
saved only the rangetable and rowMarks lists from the lower-level
PlannerInfo. But there's no reason not to remember the whole PlannerInfo,
and indeed this turns out to simplify matters in a number of places.
The immediate reason for doing this was so that the subroot will still be
accessible when we're trying to extract column statistics out of an
already-planned subquery. But now that I've done it, it seems like a good
code-beautification effort in its own right.
I also chose to get rid of the transient subrtable and subrowmark fields in
SubqueryScan nodes, in favor of having setrefs.c look up the subquery's
RelOptInfo. That required changing all the APIs in setrefs.c to pass
PlannerInfo not PlannerGlobal, which was a large but quite mechanical
transformation.
One side-effect not foreseen at the beginning is that this finally broke
inheritance_planner's assumption that replanning the same subquery RTE N
times would necessarily give interchangeable results each time. That
assumption was always pretty risky, but now we really have to make a
separate RTE for each instance so that there's a place to carry the
separate subroots.
Due to tuple-slot mismanagement, evaluation of WHEN conditions for AFTER
ROW UPDATE triggers could crash if there had been a BEFORE ROW trigger
fired for the same update. Fix by not trying to overload the use of
estate->es_trig_tuple_slot. Per report from Yoran Heling.
Back-patch to 9.0, when trigger WHEN conditions were introduced.
This requires adjusting the API for syscache callback functions: they now
get a hash value, not a TID, to identify the target tuple. Most of them
weren't paying any attention to that argument anyway, but plancache did
require a small amount of fixing.
Also, improve performance a trifle by avoiding sending duplicate inval
messages when a heap_update isn't changing the catcache lookup columns.
Somebody thought it'd be cute to invent a set of Node tag numbers that were
defined independently of, and indeed conflicting with, the main tag-number
list. While this accidentally failed to fail so far, it would certainly
lead to trouble as soon as anyone wanted to, say, apply copyObject to these
node types. Clang was already complaining about the use of makeNode on
these tags, and I think quite rightly so. Fix by pushing these node
definitions into the mainstream, including putting replnodes.h where it
belongs.
This means that they can initially be added to a large existing table
without checking its initial contents, but new tuples must comply to
them; a separate pass invoked by ALTER TABLE / VALIDATE can verify
existing data and ensure it complies with the constraint, at which point
it is marked validated and becomes a normal part of the table ecosystem.
An non-validated CHECK constraint is ignored in the planner for
constraint_exclusion purposes; when validated, cached plans are
recomputed so that partitioning starts working right away.
This patch also enables domains to have unvalidated CHECK constraints
attached to them as well by way of ALTER DOMAIN / ADD CONSTRAINT / NOT
VALID, which can later be validated with ALTER DOMAIN / VALIDATE
CONSTRAINT.
Thanks to Thom Brown, Dean Rasheed and Jaime Casanova for the various
reviews, and Robert Hass for documentation wording improvement
suggestions.
This patch was sponsored by Enova Financial.
The initial commit of the ALTER TABLE ADD FOREIGN KEY NOT VALID feature
failed to support labeling such constraints as deferrable. The best fix
for this seems to be to fold NOT VALID into ConstraintAttributeSpec.
That's a bit more general than the documented syntax, but it allows
better-targeted syntax error messages.
In addition, do some mostly-but-not-entirely-cosmetic code review for
the whole NOT VALID patch.
avoids the overhead of one function call when calling MemoryContextReset(),
and it seems like the isReset optimization would be applicable to any new
memory context we might invent in the future anyway.
This buys back the overhead I just added in previous patch to always call
MemoryContextReset() in ExecScan, even when there's no quals or projections.
Instead, foreign tables are treated just like views: permissions can
be granted using GRANT privilege ON [TABLE] foreign_table_name TO role,
and revoked similarly. GRANT/REVOKE .. FOREIGN TABLE is no longer
supported, just as we don't support GRANT/REVOKE .. VIEW. The set of
accepted permissions for foreign tables is now identical to the set for
regular tables, and views.
Per report from Thom Brown, and subsequent discussion.
The previous coding failed to account properly for the costs of evaluating
the input expressions of aggregates and window functions, as seen in a
recent gripe from Claudio Freire. (I said at the time that it wasn't
counting these costs at all; but on closer inspection, it was effectively
charging these costs once per output tuple. That is completely wrong for
aggregates, and not exactly right for window functions either.)
There was also a hard-wired assumption that aggregates and window functions
had procost 1.0, which is now fixed to respect the actual cataloged costs.
The costing of WindowAgg is still pretty bogus, since it doesn't try to
estimate the effects of spilling data to disk, but that seems like a
separate issue.
This syntax allows a standalone table to be made into a typed table,
or a typed table to be made standalone. This is possibly a mildly
useful feature in its own right, but the real motivation for this
change is that we need it to make pg_upgrade work with typed tables.
This doesn't actually fix that problem, but it's necessary
infrastructure.
Noah Misch
Per spec we ought to apply select_common_collation() across the expressions
in each column of the VALUES table. The original coding was just taking
the first row and assuming it was representative.
This patch adds a field to struct RangeTblEntry to carry the resolved
collations, so initdb is forced for changes in stored rule representation.
Since collation is effectively an argument, not a property of the function,
FmgrInfo is really the wrong place for it; and this becomes critical in
cases where a cached FmgrInfo is used for varying purposes that might need
different collation settings. Fix by passing it in FunctionCallInfoData
instead. In particular this allows a clean fix for bug #5970 (record_cmp
not working). This requires touching a bit more code than the original
method, but nobody ever thought that collations would not be an invasive
patch...
The previous coding set attinhcount too high in some cases, resulting in
an undumpable, undroppable column. Per bug #5856, reported by Naoya
Anzai. See also commit 31b6fc06d8, which
fixes a similar bug in ALTER TABLE .. ADD CONSTRAINT.
Patch by Noah Misch.
In nearly all cases, the caller already knows the correct collation, and
in a number of places, the value the caller has handy is more correct than
the default for the type would be. (In particular, this patch makes it
significantly less likely that eval_const_expressions will result in
changing the exposed collation of an expression.) So an internal lookup
is both expensive and wrong.
Instead of playing cute games with pathkeys, just build a direct
representation of the intended sub-select, and feed it through
query_planner to get a Path for the index access. This is a bit slower
than 9.1's previous method, since we'll duplicate most of the overhead of
query_planner; but since the whole optimization only applies to rather
simple single-table queries, that probably won't be much of a problem in
practice. The advantage is that we get to do the right thing when there's
a partial index that needs the implicit IS NOT NULL clause to be usable.
Also, although this makes planagg.c be a bit more closely tied to the
ordering of operations in grouping_planner, we can get rid of some coupling
to lower-level parts of the planner. Per complaint from Marti Raudsepp.
All expression nodes now have an explicit output-collation field, unless
they are known to only return a noncollatable data type (such as boolean
or record). Also, nodes that can invoke collation-aware functions store
a separate field that is the collation value to pass to the function.
This avoids confusion that arises when a function has collatable inputs
and noncollatable output type, or vice versa.
Also, replace the parser's on-the-fly collation assignment method with
a post-pass over the completed expression tree. This allows us to use
a more complex (and hopefully more nearly spec-compliant) assignment
rule without paying for it in extra storage in every expression node.
Fix assorted bugs in the planner's handling of collations by making
collation one of the defining properties of an EquivalenceClass and
by converting CollateExprs into discardable RelabelType nodes during
expression preprocessing.
CollateClause is now used only in raw grammar output, and CollateExpr after
parse analysis. This is for clarity and to avoid carrying collation names
in post-analysis parse trees: that's both wasteful and possibly misleading,
since the collation's name could be changed while the parsetree still
exists.
Also, clean up assorted infelicities and omissions in processing of the
node type.
The initial collations patch treated a COLLATE spec as part of a TypeName,
following what can only be described as brain fade on the part of the SQL
committee. It's a lot more reasonable to treat COLLATE as a syntactically
separate object, so that it can be added in only the productions where it
actually belongs, rather than needing to reject it in a boatload of places
where it doesn't belong (something the original patch mostly failed to do).
In addition this change lets us meet the spec's requirement to allow
COLLATE anywhere in the clauses of a ColumnDef, and it avoids unfriendly
behavior for constructs such as "foo::type COLLATE collation".
To do this, pull collation information out of TypeName and put it in
ColumnDef instead, thus reverting most of the collation-related changes in
parse_type.c's API. I made one additional structural change, which was to
use a ColumnDef as an intermediate node in AT_AlterColumnType AlterTableCmd
nodes. This provides enough room to get rid of the "transform" wart in
AlterTableCmd too, since the ColumnDef can carry the USING expression
easily enough.
Also fix some other minor bugs that have crept in in the same areas,
like failure to copy recently-added fields of ColumnDef in copyfuncs.c.
While at it, document the formerly secret ability to specify a collation
in ALTER TABLE ALTER COLUMN TYPE, ALTER TYPE ADD ATTRIBUTE, and
ALTER TYPE ALTER ATTRIBUTE TYPE; and correct some misstatements about
what the default collation selection will be when COLLATE is omitted.
BTW, the three-parameter form of format_type() should go away too,
since it just contributes to the confusion in this area; but I'll do
that in a separate patch.
Remove the unconditional superuser permissions check in CREATE EXTENSION,
and instead define a "superuser" extension property, which when false
(not the default) skips the superuser permissions check. In this case
the calling user only needs enough permissions to execute the commands
in the extension's installation script. The superuser property is also
enforced in the same way for ALTER EXTENSION UPDATE cases.
In other ALTER EXTENSION cases and DROP EXTENSION, test ownership of
the extension rather than superuserness. ALTER EXTENSION ADD/DROP needs
to insist on ownership of the target object as well; to do that without
duplicating code, refactor comment.c's big switch for permissions checks
into a separate function in objectaddress.c.
I also removed the superuserness checks in pg_available_extensions and
related functions; there's no strong reason why everybody shouldn't
be able to see that info.
Also invent an IF NOT EXISTS variant of CREATE EXTENSION, and use that
in pg_dump, so that dumps won't fail for installed-by-default extensions.
We don't have any of those yet, but we will soon.
This is all per discussion of wrapping the standard procedural languages
into extensions. I'll make those changes in a separate commit; this is
just putting the core infrastructure in place.
The originally committed patch for modifying CTEs didn't interact well
with EXPLAIN, as noted by myself, and also had corner-case problems with
triggers, as noted by Dean Rasheed. Those problems show it is really not
practical for ExecutorEnd to call any user-defined code; so split the
cleanup duties out into a new function ExecutorFinish, which must be called
between the last ExecutorRun call and ExecutorEnd. Some Asserts have been
added to these functions to help verify correct usage.
It is no longer necessary for callers of the executor to call
AfterTriggerBeginQuery/AfterTriggerEndQuery for themselves, as this is now
done by ExecutorStart/ExecutorFinish respectively. If you really need to
suppress that and do it for yourself, pass EXEC_FLAG_SKIP_TRIGGERS to
ExecutorStart.
Also, refactor portal commit processing to allow for the possibility that
PortalDrop will invoke user-defined code. I think this is not actually
necessary just yet, since the portal-execution-strategy logic forces any
non-pure-SELECT query to be run to completion before we will consider
committing. But it seems like good future-proofing.
This patch implements data-modifying WITH queries according to the
semantics that the updates all happen with the same command counter value,
and in an unspecified order. Therefore one WITH clause can't see the
effects of another, nor can the outer query see the effects other than
through the RETURNING values. And attempts to do conflicting updates will
have unpredictable results. We'll need to document all that.
This commit just fixes the code; documentation updates are waiting on
author.
Marko Tiikkaja and Hitoshi Harada
The recent additions for FDW support required checking foreign-table-ness
in several places in the parse/plan chain. While it's not clear whether
that would really result in a noticeable slowdown, it seems best to avoid
any performance risk by keeping a copy of the relation's relkind in
RangeTblEntry. That might have some other uses later, anyway.
Per discussion.
This commit provides the core code and documentation needed. A contrib
module test case will follow shortly.
Shigeru Hanada, Jan Urbanski, Heikki Linnakangas
Add a fdwhandler column to pg_foreign_data_wrapper, plus HANDLER options
in the CREATE FOREIGN DATA WRAPPER and ALTER FOREIGN DATA WRAPPER commands,
plus pg_dump support for same. Also invent a new pseudotype fdw_handler
with properties similar to language_handler.
This is split out of the "FDW API" patch for ease of review; it's all stuff
we will certainly need, regardless of any other details of the FDW API.
FDW handler functions will not actually get called yet.
In passing, fix some omissions and infelicities in foreigncmds.c.
Shigeru Hanada, Jan Urbanski, Heikki Linnakangas
That function was supposing that indexoid == 0 for a hypothetical index,
but that is not likely to be true in any non-toy implementation of an index
adviser, since assigning a fake OID is the only way to know at EXPLAIN time
which hypothetical index got selected. Fix by adding a flag to
IndexOptInfo to mark hypothetical indexes. Back-patch to 9.0 where
get_actual_variable_range() was added.
Gurjeet Singh
- collowner field
- CREATE COLLATION
- ALTER COLLATION
- DROP COLLATION
- COMMENT ON COLLATION
- integration with extensions
- pg_dump support for the above
- dependency management
- psql tab completion
- psql \dO command
This follows recent discussions, so it's quite a bit different from
Dimitri's original. There will probably be more changes once we get a bit
of experience with it, but let's get it in and start playing with it.
This is still just core code. I'll start converting contrib modules
shortly.
Dimitri Fontaine and Tom Lane
Flattening of subquery range tables during setrefs.c could lead to the
rangetable indexes in PlanRowMark nodes not matching up with the column
names previously assigned to the corresponding resjunk ctid (resp. tableoid
or wholerow) columns. Typical symptom would be either a "cannot extract
system attribute from virtual tuple" error or an Assert failure. This
wasn't a problem before 9.0 because we didn't support FOR UPDATE below the
top query level, and so the final flattening could never renumber an RTE
that was relevant to FOR UPDATE. Fix by using a plan-tree-wide unique
number for each PlanRowMark to label the associated resjunk columns, so
that the number need not change during flattening.
Per report from David Johnston (though I'm darned if I can see how this got
past initial testing of the relevant code). Back-patch to 9.0.
This is an essential component of making the extension feature usable;
first because it's needed in the process of converting an existing
installation containing "loose" objects of an old contrib module into
the extension-based world, and second because we'll have to use it
in pg_dump --binary-upgrade, as per recent discussion.
Loosely based on part of Dimitri Fontaine's ALTER EXTENSION UPGRADE
patch.
This patch adds the server infrastructure to support extensions.
There is still one significant loose end, namely how to make it play nice
with pg_upgrade, so I am not yet committing the changes that would make
all the contrib modules depend on this feature.
In passing, fix a disturbingly large amount of breakage in
AlterObjectNamespace() and callers.
Dimitri Fontaine, reviewed by Anssi Kääriäinen,
Itagaki Takahiro, Tom Lane, and numerous others
This adds collation support for columns and domains, a COLLATE clause
to override it per expression, and B-tree index support.
Peter Eisentraut
reviewed by Pavel Stehule, Itagaki Takahiro, Robert Haas, Noah Misch
FK constraints that are marked NOT VALID may later be VALIDATED, which uses an
ShareUpdateExclusiveLock on constraint table and RowShareLock on referenced
table. Significantly reduces lock strength and duration when adding FKs.
New state visible from psql.
Simon Riggs, with reviews from Marko Tiikkaja and Robert Haas
Waiting for relation locks can lead to starvation - it pins down an
autovacuum worker for as long as the lock is held. But if we're doing
an anti-wraparound vacuum, then we still wait; maintenance can no longer
be put off.
To assist with troubleshooting, if log_autovacuum_min_duration >= 0,
we log whenever an autovacuum or autoanalyze is skipped for this reason.
Per a gripe by Josh Berkus, and ensuing discussion.
This feature allows a unique or pkey constraint to be created using an
already-existing unique index. While the constraint isn't very
functionally different from the bare index, it's nice to be able to do that
for documentation purposes. The main advantage over just issuing a plain
ALTER TABLE ADD UNIQUE/PRIMARY KEY is that the index can be created with
CREATE INDEX CONCURRENTLY, so that there is not a long interval where the
table is locked against updates.
On the way, refactor some of the code in DefineIndex() and index_create()
so that we don't have to pass through those functions in order to create
the index constraint's catalog entries. Also, in parse_utilcmd.c, pass
around the ParseState pointer in struct CreateStmtContext to save on
notation, and add error location pointers to some error reports that didn't
have one before.
Gurjeet Singh, reviewed by Steve Singer and Tom Lane
In an inherited UPDATE/DELETE, each target table has its own subplan,
because it might have a column set different from other targets. This
means that the resjunk columns we add to support EvalPlanQual might be
at different physical column numbers in each subplan. The EvalPlanQual
rewrite I did for 9.0 failed to account for this, resulting in possible
misbehavior or even crashes during concurrent updates to the same row,
as seen in a recent report from Gordon Shannon. Revise the data structure
so that we track resjunk column numbers separately for each subplan.
I also chose to move responsibility for identifying the physical column
numbers back to executor startup, instead of assuming that numbers derived
during preprocess_targetlist would stay valid throughout subsequent
massaging of the plan. That's a bit slower, so we might want to consider
undoing it someday; but it would complicate the patch considerably and
didn't seem justifiable in a bug fix that has to be back-patched to 9.0.
Foreign tables are a core component of SQL/MED. This commit does
not provide a working SQL/MED infrastructure, because foreign tables
cannot yet be queried. Support for foreign table scans will need to
be added in a future patch. However, this patch creates the necessary
system catalog structure, syntax support, and support for ancillary
operations such as COMMENT and SECURITY LABEL.
Shigeru Hanada, heavily revised by Robert Haas
This is advantageous first because it allows us to hash the smaller table
regardless of the outer-join type, and second because hash join can be more
flexible than merge join in dealing with arbitrary join quals in a FULL
join. For merge join all the join quals have to be mergejoinable, but hash
join will work so long as there's at least one hashjoinable qual --- the
others can be any condition. (This is true essentially because we don't
keep per-inner-tuple match flags in merge join, while hash join can do so.)
To do this, we need a has-it-been-matched flag for each tuple in the
hashtable, not just one for the current outer tuple. The key idea that
makes this practical is that we can store the match flag in the tuple's
infomask, since there are lots of bits there that are of no interest for a
MinimalTuple. So we aren't increasing the size of the hashtable at all for
the feature.
To write this without turning the hash code into even more of a pile of
spaghetti than it already was, I rewrote ExecHashJoin in a state-machine
style, similar to ExecMergeJoin. Other than that decision, it was pretty
straightforward.
This commit replaces pg_class.relistemp with pg_class.relpersistence;
and also modifies the RangeVar node type to carry relpersistence rather
than istemp. It also removes removes rd_istemp from RelationData and
instead performs the correct computation based on relpersistence.
For clarity, we add three new macros: RelationNeedsWAL(),
RelationUsesLocalBuffers(), and RelationUsesTempNamespace(), so that we
can clarify the purpose of each check that previous depended on
rd_istemp.
This is intended as infrastructure for the upcoming unlogged tables
patch, as well as for future possible work on global temporary tables.
This is a heavily revised version of builtin_knngist_core-0.9. The
ordering operators are no longer mixed in with actual quals, which would
have confused not only humans but significant parts of the planner.
Instead, ordering operators are carried separately throughout planning and
execution.
Since the API for ambeginscan and amrescan functions had to be changed
anyway, this commit takes the opportunity to rationalize that a bit.
RelationGetIndexScan no longer forces a premature index_rescan call;
instead, callers of index_beginscan must call index_rescan too. Aside from
making the AM-side initialization logic a bit less peculiar, this has the
advantage that we do not make a useless extra am_rescan call when there are
runtime key values. AMs formerly could not assume that the key values
passed to amrescan were actually valid; now they can.
Teodor Sigaev and Tom Lane
Formerly we looked up the operators associated with each index (caching
them in relcache) and then the planner looked up the btree opfamily
containing such operators in order to build the btree-centric pathkey
representation that describes the index's sort order. This is quite
pointless for btree indexes: we might as well just use the index's opfamily
information directly. That saves syscache lookup cycles during planning,
and furthermore allows us to eliminate the relcache's caching of operators
altogether, which may help in reducing backend startup time.
I added code to plancat.c to perform the same type of double lookup
on-the-fly if it's ever faced with a non-btree amcanorder index AM.
If such a thing actually becomes interesting for production, we should
replace that logic with some more-direct method for identifying the
corresponding btree opfamily; but it's not worth spending effort on now.
There is considerably more to do pursuant to my recent proposal to get rid
of sort-operator-based representations of sort orderings, but this patch
grabs some of the low-hanging fruit. I'll look at the remainder of that
work after the current commitfest.
This commit adds columns amoppurpose and amopsortfamily to pg_amop, and
column amcanorderbyop to pg_am. For the moment all the entries in
amcanorderbyop are "false", since the underlying support isn't there yet.
Also, extend the CREATE OPERATOR CLASS/ALTER OPERATOR FAMILY commands with
[ FOR SEARCH | FOR ORDER BY sort_operator_family ] clauses to allow the new
columns of pg_amop to be populated, and create pg_dump support for dumping
that information.
I also added some documentation, although it's perhaps a bit premature
given that the feature doesn't do anything useful yet.
Teodor Sigaev, Robert Haas, Tom Lane
We no longer need the terminating zero entry in opfamily[], so get rid of
it. Also replace assorted ad-hoc looping logic with simple for and foreach
constructs. This code is now noticeably more readable than it was an hour
ago; credit to Robert for seeing that it could be simplified.
Fix things so that top-N sorting can be used in child Sort nodes of a
MergeAppend node, when there is a LIMIT and no intervening joins or
grouping. Actually doing this on the executor side isn't too bad,
but it's a bit messier to get the planner to cost it properly.
Per gripe from Robert Haas.
In passing, fix an oversight in the original top-N-sorting patch:
query_planner should not assume that a LIMIT can be used to make an
explicit sort cheaper when there will be grouping or aggregation in
between. Possibly this should be back-patched, but I'm not sure the
mistake is serious enough to be a real problem in practice.
Per my recent proposal, get rid of all the direct inspection of indexes
and manual generation of paths in planagg.c. Instead, set up
EquivalenceClasses for the aggregate argument expressions, and let the
regular path generation logic deal with creating paths that can satisfy
those sort orders. This makes planagg.c a bit more visible to the rest
of the planner than it was originally, but the approach is basically a lot
cleaner than before. A major advantage of doing it this way is that we get
MIN/MAX optimization on inheritance trees (using MergeAppend of indexscans)
practically for free, whereas in the old way we'd have had to add a whole
lot more duplicative logic.
One small disadvantage of this approach is that MIN/MAX aggregates can no
longer exploit partial indexes having an "x IS NOT NULL" predicate, unless
that restriction or something that implies it is specified in the query.
The previous implementation was able to use the added "x IS NOT NULL"
condition as an extra predicate proof condition, but in this version we
rely entirely on indexes that are considered usable by the main planning
process. That seems a fair tradeoff for the simplicity and functionality
gained.
and related routines.
We already had a redundant FunctionCallInfoData struct in FuncExprState,
but were using that copy only in set-returning-function cases, to avoid
keeping function evaluation state in the expression tree for the benefit
of plpgsql's "simple expression" logic. But of course that didn't work
anyway. Given the recent fixes in plpgsql there is no need to have two
separate behaviors here. Getting rid of the local FunctionCallInfoData
structs should make things a little faster (because we don't need to do
InitFunctionCallInfoData each time), and it also makes for a noticeable
reduction in stack space consumption during recursive calls.
The core of this patch is hash_array() and associated typcache
infrastructure, which works just about exactly like the existing support
for array comparison.
In addition I did some work to ensure that the planner won't think that an
array type is hashable unless its element type is hashable, and similarly
for sorting. This includes adding a datatype parameter to op_hashjoinable
and op_mergejoinable, and adding an explicit "hashable" flag to
SortGroupClause. The lack of a cross-check on the element type was a
pre-existing bug in mergejoin support --- but it didn't matter so much
before, because if you couldn't sort the element type there wasn't any good
alternative to failing anyhow. Now that we have the alternative of hashing
the array type, there are cases where we can avoid a failure by being picky
at the planner stage, so it's time to be picky.
The issue of exactly how to combine the per-element hash values to produce
an array hash is still open for discussion, but the rest of this is pretty
solid, so I'll commit it as-is.
After much expenditure of effort, we've got this to the point where the
performance penalty is pretty minimal in typical cases.
Andrew Dunstan, reviewed by Brendan Jurd, Dean Rasheed, and Tom Lane
A couple of places in the planner need to generate whole-row Vars, and were
cutting corners by setting vartype = RECORDOID in the Vars, even in cases
where there's an identifiable named composite type for the RTE being
referenced. While we mostly got away with this, it failed when there was
also a parser-generated whole-row reference to the same RTE, because the
two Vars weren't equal() due to the difference in vartype. Fix by
providing a subroutine the planner can call to generate whole-row Vars
the same way the parser does.
Per bug #5716 from Andrew Tipton. Back-patch to 9.0 where one of the bogus
calls was introduced (the other one is new in HEAD).
This is not the hoped-for facility of using INSERT/UPDATE/DELETE inside
a WITH, but rather the other way around. It seems useful in its own
right anyway.
Note: catversion bumped because, although the contents of stored rules
might look compatible, there's actually a subtle semantic change.
A single Query containing a WITH and INSERT...VALUES now represents
writing the WITH before the INSERT, not before the VALUES. While it's
not clear that that matters to anyone, it seems like a good idea to
have it cited in the git history for catversion.h.
Original patch by Marko Tiikkaja, with updating and cleanup by
Hitoshi Harada.
This patch eliminates the former need to sort the output of an Append scan
when an ordered scan of an inheritance tree is wanted. This should be
particularly useful for fast-start cases such as queries with LIMIT.
Original patch by Greg Stark, with further hacking by Hans-Jurgen Schonig,
Robert Haas, and Tom Lane.
This patch adds the SQL-standard concept of an INSTEAD OF trigger, which
is fired instead of performing a physical insert/update/delete. The
trigger function is passed the entire old and/or new rows of the view,
and must figure out what to do to the underlying tables to implement
the update. So this feature can be used to implement updatable views
using trigger programming style rather than rule hacking.
In passing, this patch corrects the names of some columns in the
information_schema.triggers view. It seems the SQL committee renamed
them somewhere between SQL:99 and SQL:2003.
Dean Rasheed, reviewed by Bernd Helmle; some additional hacking by me.
The point of a PlaceHolderVar is to allow a non-strict expression to be
evaluated below an outer join, after which its value bubbles up like a Var
and can be forced to NULL when the outer join's semantics require that.
However, there was a serious design oversight in that, namely that we
didn't ensure that there was actually a correct place in the plan tree
to evaluate the placeholder :-(. It may be necessary to delay evaluation
of an outer join to ensure that a placeholder that should be evaluated
below the join can be evaluated there. Per recent bug report from Kirill
Simonov.
Back-patch to 8.4 where the PlaceHolderVar mechanism was introduced.
This is intended as infrastructure to support integration with label-based
mandatory access control systems such as SE-Linux. Further changes (mostly
hooks) will be needed, but this is a big chunk of it.
KaiGai Kohei and Robert Haas
The implicitly created sequence was created as owned by the current user,
who could be different from the table owner, eg if current user is a
superuser or some member of the table's owning role. This caused sanity
checks in the SEQUENCE OWNED BY code to spit up. Although possibly we
don't need those sanity checks, the safest fix seems to be to make sure
the implicit sequence is assigned the same owner role as the table has.
(We still do all permissions checks as the current user, however.)
Per report from Josh Berkus.
Back-patch to 9.0. The bug goes back to the invention of SEQUENCE OWNED BY
in 8.2, but the fix requires an API change for DefineRelation(), which seems
to have potential for breaking third-party code if done in a minor release.
Given the lack of prior complaints, it's probably not worth fixing in the
stable branches.
other columns to be referenced without listing them in GROUP BY, so long as
the primary key column(s) are listed in GROUP BY.
Eventually we should also allow functional dependency on a UNIQUE constraint
when the columns are marked NOT NULL, but that has to wait until NOT NULL
constraints are represented in pg_constraint, because we need to have
pg_constraint OIDs for all the conditions needed to ensure functional
dependency.
Peter Eisentraut, reviewed by Alex Hunsaker and Tom Lane
a pass-by-reference datatype with a nontrivial projection step.
We were using the same memory context for the projection operation as for
the temporary context used by the hashtable routines in execGrouping.c.
However, the hashtable routines feel free to reset their temp context at
any time, which'd lead to destroying input data that was still needed.
Report and diagnosis by Tao Ma.
Back-patch to 8.1, where the problem was introduced by the changes that
allowed us to work with "virtual" tuples instead of materializing intermediate
tuple values everywhere. The earlier code looks quite similar, but it doesn't
suffer the problem because the data gets copied into another context as a
result of having to materialize ExecProject's output tuple.
relation using the general PARAM_EXEC executor parameter mechanism, rather
than the ad-hoc kluge of passing the outer tuple down through ExecReScan.
The previous method was hard to understand and could never be extended to
handle parameters coming from multiple join levels. This patch doesn't
change the set of possible plans nor have any significant performance effect,
but it's necessary infrastructure for future generalization of the concept
of an inner indexscan plan.
ExecReScan's second parameter is now unused, so it's removed.
constraint exclusion on an inheritance set that is the target of an UPDATE
or DELETE query. Per gripe from Marc Cousin. Back-patch to 8.4 where
the feature was introduced.
This operates in the same way as other CREATE OR REPLACE commands, ie,
it replaces everything but the ownership and ACL lists of an existing
entry, and requires the caller to have owner privileges for that entry.
While modifying an existing language has some use in development scenarios,
in typical usage all the "replaced" values come from pg_pltemplate so there
will be no actual change in the language definition. The reason for adding
this is mainly to allow programs to ensure that a language exists without
triggering an error if it already does exist.
This commit just adds and documents the new option. A followon patch
will use it to clean up some unpleasant cases in pg_dump and pg_regress.
In addition, add support for a "payload" string to be passed along with
each notify event.
This implementation should be significantly more efficient than the old one,
and is also more compatible with Hot Standby usage. There is not yet any
facility for HS slaves to receive notifications generated on the master,
although such a thing is possible in future.
Joachim Wieland, reviewed by Jeff Davis; also hacked on by me.
compilers, by applying a configure check to see if the compiler will accept
an unreferenced "static inline foo ..." function without warnings. It is
believed that such warnings are the only reason not to declare inlined
functions in headers, if the compiler understands "inline" at all.
Kurt Harriman
This patch allows the frame to start from CURRENT ROW (in either RANGE or
ROWS mode), and it also adds support for ROWS n PRECEDING and ROWS n FOLLOWING
start and end points. (RANGE value PRECEDING/FOLLOWING isn't there yet ---
the grammar works, but that's all.)
Hitoshi Harada, reviewed by Pavel Stehule
VACUUM FULL INPLACE), along with a boatload of subsidiary code and complexity.
Per discussion, the use case for this method of vacuuming is no longer large
enough to justify maintaining it; not to mention that we don't wish to invest
the work that would be needed to make it play nicely with Hot Standby.
Aside from the code directly related to old-style VACUUM FULL, this commit
removes support for certain WAL record types that could only be generated
within VACUUM FULL, redirect-pointer removal in heap_page_prune, and
nontransactional generation of cache invalidation sinval messages (the last
being the sticking point for Hot Standby).
We still have to retain all code that copes with finding HEAP_MOVED_OFF and
HEAP_MOVED_IN flag bits on existing tuples. This can't be removed as long
as we want to support in-place update from pre-9.0 databases.
Attributes can now have options, just as relations and tablespaces do, and
the reloptions code is used to parse, validate, and store them. For
simplicity and because these options are not performance critical, we store
them in a separate cache rather than the main relcache.
Thanks to Alex Hunsaker for the review.
pg_constraint before searching pg_trigger. This allows saner handling of
corner cases; in particular we now say "constraint is not deferrable"
rather than "constraint does not exist" when the command is applied to
a constraint that's inherently non-deferrable. Per a gripe several months
ago from hubert depesz lubaczewski.
To make this work without breaking user-defined constraint triggers,
we have to add entries for them to pg_constraint. However, in return
we can remove the pgconstrname column from pg_constraint, which represents
a fairly sizable space savings. I also replaced the tgisconstraint column
with tgisinternal; the old meaning of tgisconstraint can now be had by
testing for nonzero tgconstraint, while there is no other way to get
the old meaning of nonzero tgconstraint, namely that the trigger was
internally generated rather than being user-created.
In passing, fix an old misstatement in the docs and comments, namely that
pg_trigger.tgdeferrable is exactly redundant with pg_constraint.condeferrable.
Actually, we mark RI action triggers as nondeferrable even when they belong to
a nominally deferrable FK constraint. The SET CONSTRAINTS code now relies on
that instead of hard-coding a list of exception OIDs.
parse analysis phase, rather than at execution time. This makes parameter
handling work the same as it does in ordinary plannable queries, and in
particular fixes the incompatibility that Pavel pointed out with plpgsql's
new handling of variable references. plancache.c gets a little bit
grottier, but the alternatives seem worse.
VACUUM FULL was renamed to VACUUM FULL INPLACE. Also added a new
option -i, --inplace for vacuumdb to perform FULL INPLACE vacuuming.
Since the new VACUUM FULL uses CLUSTER infrastructure, we cannot
use it for system tables. VACUUM FULL for system tables always
fall back into VACUUM FULL INPLACE silently.
Itagaki Takahiro, reviewed by Jeff Davis and Simon Riggs.
peculiar variant of UNION ALL, and so wouldn't likely get written directly
as-is, it's possible for it to arise as a result of simplification of
less-obviously-silly queries. In particular, now that we can do flattening
of subqueries that have constant outputs and are underneath an outer join,
it's possible for the case to result from simplification of queries of the
type exhibited in bug #5263. Back-patch to 8.4 to avoid a functionality
regression for this type of query.
This patch only supports seq_page_cost and random_page_cost as parameters,
but it provides the infrastructure to scalably support many more.
In particular, we may want to add support for effective_io_concurrency,
but I'm leaving that as future work for now.
Thanks to Tom Lane for design help and Alvaro Herrera for the review.
8.2beta but never carried out. This avoids repetitive tests of whether the
argument is of scalar or composite type. Also, be a bit more paranoid about
composite arguments in some places where we previously weren't checking.
to be just a minor extension of the previous patch that made "x IS NULL"
indexable, because we can treat the IS NOT NULL condition as if it were
"x < NULL" or "x > NULL" (depending on the index's NULLS FIRST/LAST option),
just like IS NULL is treated like "x = NULL". Aside from any possible
usefulness in its own right, this is an important improvement for
index-optimized MAX/MIN aggregates: it is now reliably possible to get
a column's min or max value cheaply, even when there are a lot of nulls
cluttering the interesting end of the index.
and teach ANALYZE to compute such stats for tables that have subclasses.
Per my proposal of yesterday.
autovacuum still needs to be taught about running ANALYZE on parent tables
when their subclasses change, but the feature is useful even without that.
Index expression columns are now named after the FigureColname result for
their expressions, rather than always being "pg_expression_N". Digits are
appended to this name if needed to make the column name unique within the
index. (That happens for regular columns too, thus fixing the old problem
that CREATE INDEX fooi ON foo (f1, f1) fails. Before exclusion indexes
there was no real reason to do such a thing, but now maybe there is.)
Default names for indexes and associated constraints now include the column
names of all their columns, not only the first one as in previous practice.
(Of course, this will be truncated as needed to fit in NAMEDATALEN. Also,
pkey indexes retain the historical behavior of not naming specific columns
at all.)
An example of the results:
regression=# create table foo (f1 int, f2 text,
regression(# exclude (f1 with =, lower(f2) with =));
NOTICE: CREATE TABLE / EXCLUDE will create implicit index "foo_f1_lower_exclusion" for table "foo"
CREATE TABLE
regression=# \d foo_f1_lower_exclusion
Index "public.foo_f1_lower_exclusion"
Column | Type | Definition
--------+---------+------------
f1 | integer | f1
lower | text | lower(f2)
btree, for table "public.foo"
non-kluge method for controlling the order in which values are fed to an
aggregate function. At the same time eliminate the old implementation
restriction that DISTINCT was only supported for single-argument aggregates.
Possibly release-notable behavioral change: formerly, agg(DISTINCT x)
dropped null values of x unconditionally. Now, it does so only if the
agg transition function is strict; otherwise nulls are treated as DISTINCT
normally would, ie, you get one copy.
Andrew Gierth, reviewed by Hitoshi Harada
This patch also removes buffer-usage statistics from the track_counts
output, since this (or the global server statistics) is deemed to be a better
interface to this information.
Itagaki Takahiro, reviewed by Euler Taveira de Oliveira.
support any indexable commutative operator, not just equality. Two rows
violate the exclusion constraint if "row1.col OP row2.col" is TRUE for
each of the columns in the constraint.
Jeff Davis, reviewed by Robert Haas
by adding a requirement that build_join_rel add new join RelOptInfos to the
appropriate list immediately at creation. Per report from Robert Haas,
the list_concat_unique_ptr() calls that this change eliminates were taking
the lion's share of the runtime in larger join problems. This doesn't do
anything to fix the fundamental combinatorial explosion in large join
problems, but it should push out the threshold of pain a bit further.
Note: because this changes the order in which joinrel lists are built,
it might result in changes in selected plans in cases where different
alternatives have exactly the same costs. There is one example in the
regression tests.
checked to determine whether the trigger should be fired.
For BEFORE triggers this is mostly a matter of spec compliance; but for AFTER
triggers it can provide a noticeable performance improvement, since queuing of
a deferred trigger event and re-fetching of the row(s) at end of statement can
be short-circuited if the trigger does not need to be fired.
Takahiro Itagaki, reviewed by KaiGai Kohei.
adopted for EXPLAIN. This will allow additional options to be implemented
in future without having to make them fully-reserved keywords. The old syntax
remains available for existing options, however.
Itagaki Takahiro
mergejoin to shield it from doing mark/restore and refetches. Put an explicit
flag in MergePath so we can centralize the logic that knows about this,
and add costing logic that considers using Materialize even when it's not
forced by the previously-existing considerations. This is in response to
a discussion back in August that suggested that materializing an inner
indexscan can be helpful when the refetch percentage is high enough.
As proof of concept, modify plpgsql to use the hooks. plpgsql is still
inserting $n symbols textually, but the "back end" of the parsing process now
goes through the ParamRef hook instead of using a fixed parameter-type array,
and then execution only fetches actually-referenced parameters, using a hook
added to ParamListInfo.
Although there's a lot left to be done in plpgsql, this already cures the
"if (TG_OP = 'INSERT' and NEW.foo ...)" problem, as illustrated by the
changed regression test.
underneath the Limit node, not atop it. This fixes the old problem that such
a query might unexpectedly return fewer rows than the LIMIT says, due to
LockRows discarding updated rows.
There is a related problem that LockRows might destroy the sort ordering
produced by earlier steps; but fixing that by pushing LockRows below Sort
would create serious performance problems that are unjustified in many
real-world applications, as well as potential deadlock problems from locking
many more rows than expected. Instead, keep the present semantics of applying
FOR UPDATE after ORDER BY within a single query level; but allow the user to
specify the other way by writing FOR UPDATE in a sub-select. To make that
work, track whether FOR UPDATE appeared explicitly in sub-selects or got
pushed down from the parent, and don't flatten a sub-select that contained an
explicit FOR UPDATE.
a lot of strange behaviors that occurred in join cases. We now identify the
"current" row for every joined relation in UPDATE, DELETE, and SELECT FOR
UPDATE/SHARE queries. If an EvalPlanQual recheck is necessary, we jam the
appropriate row into each scan node in the rechecking plan, forcing it to emit
only that one row. The former behavior could rescan the whole of each joined
relation for each recheck, which was terrible for performance, and what's much
worse could result in duplicated output tuples.
Also, the original implementation of EvalPlanQual could not re-use the recheck
execution tree --- it had to go through a full executor init and shutdown for
every row to be tested. To avoid this overhead, I've associated a special
runtime Param with each LockRows or ModifyTable plan node, and arranged to
make every scan node below such a node depend on that Param. Thus, by
signaling a change in that Param, the EPQ machinery can just rescan the
already-built test plan.
This patch also adds a prohibition on set-returning functions in the
targetlist of SELECT FOR UPDATE/SHARE. This is needed to avoid the
duplicate-output-tuple problem. It seems fairly reasonable since the
other restrictions on SELECT FOR UPDATE are meant to ensure that there
is a unique correspondence between source tuples and result tuples,
which an output SRF destroys as much as anything else does.
are named in the UPDATE's SET list.
Note: the schema of pg_trigger has not actually changed; we've just started
to use a column that was there all along. catversion bumped anyway so that
this commit is included in the history of potentially interesting changes
to system catalog contents.
Itagaki Takahiro
execMain.c and into a new plan node type LockRows. Like the recent change
to put table updating into a ModifyTable plan node, this increases planning
flexibility by allowing the operations to occur below the top level of the
plan tree. It's necessary in any case to restore the previous behavior of
having FOR UPDATE locking occur before ModifyTable does.
This partially refactors EvalPlanQual to allow multiple rows-under-test
to be inserted into the EPQ machinery before starting an EPQ test query.
That isn't sufficient to fix EPQ's general bogosity in the face of plans
that return multiple rows per test row, though. Since this patch is
mostly about getting some plan node infrastructure in place and not about
fixing ten-year-old bugs, I will leave EPQ improvements for another day.
Another behavioral change that we could now think about is doing FOR UPDATE
before LIMIT, but that too seems like it should be treated as a followon
patch.
They are now handled by a new plan node type called ModifyTable, which is
placed at the top of the plan tree. In itself this change doesn't do much,
except perhaps make the handling of RETURNING lists and inherited UPDATEs a
tad less klugy. But it is necessary preparation for the intended extension of
allowing RETURNING queries inside WITH.
Marko Tiikkaja
Create a new catalog pg_db_role_setting where they are now stored, and better
encapsulate the code that deals with settings into its realm. The old
datconfig and rolconfig columns are removed.
psql has gained a \drds command to display the settings.
Backwards compatibility warning: while the backwards-compatible system views
still have the config columns, they no longer completely represent the
configuration for a user or database.
Catalog version bumped.
inheritance parent tables are compared using equal(), instead of doing
strcmp() on the nodeToString representation. The old implementation was
always a tad cheesy, and it finally fails completely as of 8.4, now that the
node tree might contain syntax location information. equal() knows it's
supposed to ignore those fields, but strcmp() hardly can. Per recent
report from Scott Ribe.
the privileges that will be applied to subsequently-created objects.
Such adjustments are always per owning role, and can be restricted to objects
created in particular schemas too. A notable benefit is that users can
override the traditional default privilege settings, eg, the PUBLIC EXECUTE
privilege traditionally granted by default for functions.
Petr Jelinek
TupleTableSlot nodes. This eliminates the need to count in advance
how many Slots will be needed, which seems more than worth the small
increase in the amount of palloc traffic during executor startup.
The ExecCountSlots infrastructure is now all dead code, but I'll remove it
in a separate commit for clarity.
Per a comment from Robert Haas.
to create a function for it.
Procedural languages now have an additional entry point, namely a function
to execute an inline code block. This seemed a better design than trying
to hide the transient-ness of the code from the PL. As of this patch, only
plpgsql has an inline handler, but probably people will soon write handlers
for the other standard PLs.
In passing, remove the long-dead LANCOMPILER option of CREATE LANGUAGE.
Petr Jelinek
is unique and is not referenced above the join. In this case the inner
side doesn't affect the query result and can be thrown away entirely.
Although perhaps nobody would ever write such a thing by hand, it's
a reasonably common case in machine-generated SQL.
The current implementation only recognizes the case where the inner side
is a simple relation with a unique index matching the query conditions.
This is enough for the use-cases that have been shown so far, but we
might want to try to handle other cases later.
Robert Haas, somewhat rewritten by Tom
values before they get passed to the index access method. This avoids
repeated detoastings that will otherwise ensue as the comparison value
is examined by various index support functions. We have seen a couple of
reports of cases where repeated detoastings result in an order-of-magnitude
slowdown, so it seems worth adding a bit of extra logic to prevent this.
I had previously proposed trying to avoid duplicate detoastings in general,
but this fix takes care of what seems the most important case in practice
with very little effort or risk.
Back-patch to 8.4 so that the PostGIS folk won't have to wait a year to
have this fix in a production release. (The issue exists further back,
of course, but the code's diverged enough to make backpatching further a
higher-risk action. Also it appears that the possible gains may be limited
in prior releases because of different handling of lossy operators.)
by supporting conversions in places that used to demand exact rowtype match.
Since this issue is certain to come up elsewhere (in fact, already has,
in ExecEvalConvertRowtype), factor out the support code into new core
functions for tuple conversion. I chose to put these in a new source
file since heaptuple.c is already overly long.
Heavily revised version of a patch by Pavel Stehule.
This was foreseen to be a good idea long ago, but nobody had got round
to doing it. The recent patch for deferred unique constraints made
transformConstraintAttrs() ugly enough that I decided it was time.
This change will also greatly simplify parsing of deferred CHECK constraints,
if anyone ever gets around to implementing that.
While at it, add a location field to Constraint, and use that to provide
an error cursor for some of the constraint-related error messages.
The current implementation fires an AFTER ROW trigger for each tuple that
looks like it might be non-unique according to the index contents at the
time of insertion. This works well as long as there aren't many conflicts,
but won't scale to massive unique-key reassignments. Improving that case
is a TODO item.
Dean Rasheed
The original syntax made it difficult to add options without making them
into reserved words. This change parenthesizes the options to avoid that
problem, and makes provision for an explicit (and perhaps non-Boolean)
value for each option. The original syntax is still supported, but only
for the two original options ANALYZE and VERBOSE.
As a test case, add a COSTS option that can suppress the planner cost
estimates. This may be useful for including EXPLAIN output in the regression
tests, which are otherwise unable to cope with cross-platform variations in
cost estimates.
Robert Haas
random number seed each time. This is how it used to work years ago, but
we got rid of the seed reset because it was resetting the main random()
sequence and thus having undesirable effects on the rest of the system.
To fix, establish a private random number state for each execution of
geqo(), and initialize the state using the new GUC variable geqo_seed.
People who want to experiment with different random searches can do so
by changing geqo_seed, but you'll always get the same plan for the same
value of geqo_seed (if holding all other planner inputs constant, of course).
The new state is kept in PlannerInfo by adding a "void *" field reserved
for use by join_search hooks. Most of the rather bulky code changes in
this commit are just arranging to pass PlannerInfo around to all the GEQO
functions (many of which formerly didn't receive it).
Andres Freund, with some editorialization by Tom
This alters various incidental uses of C++ key words to use other similar
identifiers, so that a C++ compiler won't choke outright. You still
(probably) need extern "C" { }; around the inclusion of backend headers.
based on a patch by Kurt Harriman <harriman@acm.org>
Also add a script cpluspluscheck to check for C++ compatibility in the
future. As of right now, this passes without error for me.
types in CREATE TRIGGER. While at it, clean up the amazingly tedious and
inextensible way that the trigger event type list was handled. Per report
from Greg Sabino Mullane.
constants through full joins, as in
select * from tenk1 a full join tenk1 b using (unique1)
where unique1 = 42;
which should generate a fairly cheap plan where we apply the constraint
unique1 = 42 in each relation scan. This had been broken by my patch of
2008-06-27, which is now reverted in favor of a more invasive but hopefully
less incorrect approach. That patch was meant to prevent incorrect extraction
of OR'd indexclauses from OR conditions above an outer join. To do that
correctly we need more information than the outerjoin_delay flag can provide,
so add a nullable_relids field to RestrictInfo that records exactly which
relations are nulled by outer joins that are underneath a particular qual
clause. A side benefit is that we can make the test in create_or_index_quals
more specific: it is now smart enough to extract an OR'd indexclause into the
outer side of an outer join, even though it must not do so in the inner side.
The old coding couldn't distinguish these cases so it could not do either.
are individually labeled, rather than just grouped under an "InitPlan"
or "SubPlan" heading. This in turn makes it possible for decompilation of
a subplan reference to usefully identify which subplan it's referencing.
I also made InitPlans identify which parameter symbol(s) they compute,
so that references to those parameters elsewhere in the plan tree can
be connected to the initplan that will be executed. Per a gripe from
Robert Haas about EXPLAIN output of a WITH query being inadequate,
plus some longstanding pet peeves of my own.
of adding optional namespace and action fields to DefElem. Having three
node types that do essentially the same thing bloats the code and leads
to errors of confusion, such as in yesterday's bug report from Khee Chin.
for simple Var targetlist entries all the time, even when there are other
entries that are not simple Vars. Also, ensure that we prefetch attributes
(with slot_getsomeattrs) for all Vars in the targetlist, even those buried
within expressions. In combination these changes seem to significantly
reduce the runtime for cases where tlists are mostly but not exclusively
Vars. Per my proposal of yesterday.
"physical tlist" optimization on the outer relation (ie, force a projection
step to occur in its scan). This avoids storing useless column values when
the outer relation's tuples are written to temporary batch files.
Modified version of a patch by Michael Henderson and Ramon Lawrence.
multiple index entries in a holding area before adding them to the main index
structure. This helps because bulk insert is (usually) significantly faster
than retail insert for GIN.
This patch also removes GIN support for amgettuple-style index scans. The
API defined for amgettuple is difficult to support with fastupdate, and
the previously committed partial-match feature didn't really work with
it either. We might eventually figure a way to put back amgettuple
support, but it won't happen for 8.4.
catversion bumped because of change in GIN's pg_am entry, and because
the format of GIN indexes changed on-disk (there's a metapage now,
and possibly a pending list).
Teodor Sigaev
distribution, by creating a special fast path for the (first few) most common
values of the outer relation. Tuples having hashvalues matching the MCVs
are effectively forced to be in the first batch, so that we never write
them out to the batch temp files.
Bryce Cutt and Ramon Lawrence, with some editorialization by me.
for consistency with the (relatively) recent addition of typmod to SubLink.
An example of why it's a good idea is to be seen in the recent "failed to
locate grouping columns" bug, which wouldn't have happened if a SubPlan
exposed the same typmod info as the SubLink it was derived from.
This could be back-patched, since it doesn't affect any on-disk data format,
but for the moment it doesn't seem necessary to do so.
amgettuple or only implement amgetbitmap, instead of the former assumption
that every AM supports both APIs. Extracted with minor editorialization
from Teodor's fast-GIN-insert patch; whatever becomes of that, this seems
like a simple and reasonable generalization of the index AM interface spec.
making pull_up_sublinks() construct a full-blown JoinExpr tree representation
of IN/EXISTS SubLinks that it is able to convert to semi or anti joins.
This makes pull_up_sublinks() a shade more complex, but the gain in semantic
clarity is worth it. I still have more to do in this area to address the
previously-discussed problems, but this commit in itself fixes at least one
bug in HEAD, as shown by added regression test case.
wrappers (similar to procedural languages). This way we don't need to retain
the nearly empty libraries, and we are more free in how to implement the
wrapper API in the future.
get rid of the OID column. This eliminates the problem discovered by Heikki
back in November that 8.4's suppression of "unnecessary" junk filtering in
INSERT/SELECT could lead to an Assert failure, or storing of oids into a table
that shouldn't have them if Asserts are off. While that particular problem
could have been solved in other ways, it seems likely to be just a forerunner
of things to come if we continue to allow tables to contain rows that disagree
with the pg_class.relhasoids setting. It's better to make this operation slow
than to sacrifice performance or risk bugs in more common code paths.
Also, add ALTER TABLE SET WITH OIDS to rewrite the table to add oids.
This was a bit more controversial, but in view of the very small amount of
extra code needed given the current ALTER TABLE infrastructure, it seems best
to eliminate the asymmetry in features.
keys when considering a semi or anti join. This requires estimating the
selectivity of the merge qual as though it were a regular inner join condition.
To allow caching both that and the real outer-join-aware selectivity, split
RestrictInfo.this_selec into two fields.
This fixes one of the problems reported by Kevin Grittner.
qualifier, and add support for this in pg_dump.
This allows TOAST tables to have user-defined fillfactor, and will also
enable us to move the autovacuum parameters to reloptions without taking
away the possibility of setting values for TOAST tables.
GUC variable effective_io_concurrency controls how many concurrent block
prefetch requests will be issued.
(The best way to handle this for plain index scans is still under debate,
so that part is not applied yet --- tgl)
Greg Stark
bitmap. This is extracted from Greg Stark's posix_fadvise patch; it seems
worth committing separately, since it's potentially useful independently of
posix_fadvise.
patch. This includes the ability to force the frame to cover the whole
partition, and the ability to make the frame end exactly on the current row
rather than its last ORDER BY peer. Supporting any more of the full SQL
frame-clause syntax will require nontrivial hacking on the window aggregate
code, so it'll have to wait for 8.5 or beyond.
This doesn't do any remote or external things yet, but it gives modules
like plproxy and dblink a standardized and future-proof system for
managing their connection information.
Martin Pihlak and Peter Eisentraut
the visibility map patch that because autovacuum always sets
VacuumStmt->freeze_min_age, visibility map was never used for autovacuum,
only for manually launched vacuums. This patch introduces a new scan_all
field to VacuumStmt, indicating explicitly whether the visibility map
should be used, or the whole relation should be scanned, to advance
relfrozenxid. Anti-wraparound vacuums still need to scan all pages.
outer join clauses. Given, say,
... from a left join b on a.a1 = b.b1 where a.a1 = 42;
we'll deduce a clause b.b1 = 42 and then mark the original join clause
redundant (we can't remove it completely for reasons I don't feel like
squeezing into this log entry). However the original implementation of
that wasn't bulletproof, because clause_selectivity() wouldn't honor
this_selec if given nonzero varRelid --- which in practice meant that
it worked as desired *except* when considering index scan quals. Which
resulted in bogus underestimation of the size of the indexscan result for
an inner indexscan in an outer join, and consequently a possibly bad
choice of indexscan vs. bitmap scan. Fix by introducing an explicit test
into clause_selectivity(). Also, to make sure we don't trigger that test
in corner cases, change the convention to be that this_selec > 1, not
this_selec = 1, means it's been marked redundant. Per trouble report from
Scara Maccai.
Back-patch to 8.2, where the problem was introduced.
though it is an inner rather than outer join type. This essentially means
that we don't bother to separate "pushed down" qual conditions from actual
join quals at a semijoin plan node; which is okay because the restrictions of
SQL syntax make it impossible to have a pushed-down qual that references the
inner side of a semijoin. This allows noticeably better optimization of
IN/EXISTS cases than we had before, since the equivalence-class machinery can
now use those quals. Also fix a couple of other mistakes that had essentially
disabled the ability to unique-ify the inner relation and then join it to just
a subset of the left-hand relations. An example case using the regression
database is
select * from tenk1 a, tenk1 b
where (a.unique1,b.unique2) in (select unique1,unique2 from tenk1 c);
which is planned reasonably well by 8.3 and earlier but had been forcing a
cartesian join of a/b in CVS HEAD.
locate the target row, if the cursor was declared with FOR UPDATE or FOR
SHARE. This approach is more flexible and reliable than digging through the
plan tree; for instance it can cope with join cursors. But we still provide
the old code for use with non-FOR-UPDATE cursors. Per gripe from Robert Haas.
return the tableoid as well as the ctid for any FOR UPDATE targets that
have child tables. All child tables are listed in the ExecRowMark list,
but the executor just skips the ones that didn't produce the current row.
Curiously, this longstanding restriction doesn't seem to have been documented
anywhere; so no doc changes.
we extended the appendrel mechanism to support UNION ALL optimization. The
reason nobody noticed was that we are not actually using attr_needed data for
appendrel children; hence it seems more reasonable to rip it out than fix it.
Back-patch to 8.2 because an Assert failure is possible in corner cases.
Per examination of an example from Jim Nasby.
In HEAD, also get rid of AppendRelInfo.col_mappings, which is quite inadequate
to represent UNION ALL situations; depend entirely on translated_vars instead.
RETURNING clause, not just a SELECT as formerly.
A side effect of this patch is that when a set-returning SQL function is used
in a FROM clause, performance is improved because the output is collected into
a tuplestore within the function, rather than using the less efficient
value-per-call mechanism.
backwards scan could actually happen. In particular, pass a flag to
materialize-mode SRFs that tells them whether they need to require random
access. In passing, also suppress unneeded backward-scan overhead for a
Portal's holdStore tuplestore. Per my proposal about reducing I/O costs for
tuplestores.
via a tuplestore instead of value-per-call. Refactor a few things to reduce
ensuing code duplication with nodeFunctionscan.c. This represents the
reasonably noncontroversial part of my proposed patch to switch SQL functions
over to returning tuplestores. For the moment, SQL functions still do things
the old way. However, this change enables PL SRFs to be called in targetlists
(observe changes in plperl regression results).
until vars are distributed to rels during query_planner() startup. We don't
really need it before that, and not building it early has some advantages.
First, we don't need to put it through the various preprocessing steps, which
saves some cycles and eliminates the need for a number of routines to support
PlaceHolderInfo nodes at all. Second, this means one less unused plan for any
sub-SELECT appearing in a placeholder's expression, since we don't build
placeholder_list until after sublink expansion is complete.
that represent some expression that we desire to compute below the top level
of the plan, and then let that value "bubble up" as though it were a plain
Var (ie, a column value).
The immediate application is to allow sub-selects to be flattened even when
they are below an outer join and have non-nullable output expressions.
Formerly we couldn't flatten because such an expression wouldn't properly
go to NULL when evaluated above the outer join. Now, we wrap it in a
PlaceHolderVar and arrange for the actual evaluation to occur below the outer
join. When the resulting Var bubbles up through the join, it will be set to
NULL if necessary, yielding the correct results. This fixes a planner
limitation that's existed since 7.1.
In future we might want to use this mechanism to re-introduce some form of
Hellerstein's "expensive functions" optimization, ie place the evaluation of
an expensive function at the most suitable point in the plan tree.
implementation uses an in-memory hash table, so it will poop out for very
large recursive results ... but the performance characteristics of a
sort-based implementation would be pretty unpleasant too.
the column alias names of the RTE referenced by the Var to the RowExpr.
This is needed to allow ruleutils.c to correctly deparse FieldSelect nodes
referencing such a construct. Per my recent bug report.
Adding a field to RowExpr forces initdb (because of stored rules changes)
so this solution is not back-patchable; which is unfortunate because 8.2
and 8.3 have this issue. But it only affects EXPLAIN for some pretty odd
corner cases, so we can probably live without a solution for the back
branches.
There are some unimplemented aspects: recursive queries must use UNION ALL
(should allow UNION too), and we don't have SEARCH or CYCLE clauses.
These might or might not get done for 8.4, but even without them it's a
pretty useful feature.
There are also a couple of small loose ends and definitional quibbles,
which I'll send a memo about to pgsql-hackers shortly. But let's land
the patch now so we can get on with other development.
Yoshiyuki Asaba, with lots of help from Tatsuo Ishii and Tom Lane
This facility replaces the former mark/restore support but is otherwise
upward-compatible with previous uses. It's expected to be needed for
single evaluation of CTEs and also for window functions, so I'm committing
it separately instead of waiting for either one of those patches to be
finished. Per discussion with Greg Stark and Hitoshi Harada.
Note: I removed nodeFunctionscan's mark/restore support, instead of bothering
to update it for this change, because it was dead code anyway.
when user-defined functions used in a plan are modified. Also invalidate
plans when schemas, operators, or operator classes are modified; but for these
cases we just invalidate everything rather than tracking exact dependencies,
since these types of objects seldom change in a production database.
Tom Lane; loosely based on a patch by Martin Pihlak.
SELECT foo.*) so that it cannot be confused with a quoted identifier "*".
Instead create a separate node type A_Star to represent this notation.
Per pgsql-hackers discussion of 2007-Sep-27.
syntax to avoid a useless store into a global variable. Per experimentation,
this works better than my original thought of trying to push the code into
an out-of-line subroutine.
most node types used in expression trees (both before and after parse
analysis). This allows us to place an error cursor in many situations
where we formerly could not, because the information wasn't available
beyond the very first level of parse analysis. There's a fair amount
of work still to be done to persuade individual ereport() calls to actually
include an error location, but this gets the initdb-forcing part of the
work out of the way; and the situation is already markedly better than
before for complaints about unimplementable implicit casts, such as
CASE and UNION constructs with incompatible alternative data types.
Per my proposal of a few days ago.
into nodes/nodeFuncs, so as to reduce wanton cross-subsystem #includes inside
the backend. There's probably more that should be done along this line,
but this is a start anyway.
subqueries into the same thing you'd have gotten from IN (except always with
unknownEqFalse = true, so as to get the proper semantics for an EXISTS).
I believe this fixes the last case within CVS HEAD in which an EXISTS could
give worse performance than an equivalent IN subquery.
The tricky part of this is that if the upper query probes the EXISTS for only
a few rows, the hashing implementation can actually be worse than the default,
and therefore we need to make a cost-based decision about which way to use.
But at the time when the planner generates plans for subqueries, it doesn't
really know how many times the subquery will be executed. The least invasive
solution seems to be to generate both plans and postpone the choice until
execution. Therefore, in a query that has been optimized this way, EXPLAIN
will show two subplans for the EXISTS, of which only one will actually get
executed.
There is a lot more that could be done based on this infrastructure: in
particular it's interesting to consider switching to the hash plan if we start
out using the non-hashed plan but find a lot more upper rows going by than we
expected. I have therefore left some minor inefficiencies in place, such as
initializing both subplans even though we will currently only use one.
the old JOIN_IN code, but antijoins are new functionality.) Teach the planner
to convert appropriate EXISTS and NOT EXISTS subqueries into semi and anti
joins respectively. Also, LEFT JOINs with suitable upper-level IS NULL
filters are recognized as being anti joins. Unify the InClauseInfo and
OuterJoinInfo infrastructure into "SpecialJoinInfo". With that change,
it becomes possible to associate a SpecialJoinInfo with every join attempt,
which permits some cleanup of join selectivity estimation. That needs to be
taken much further than this patch does, but the next step is to change the
API for oprjoin selectivity functions, which seems like material for a
separate patch. So for the moment the output size estimates for semi and
especially anti joins are quite bogus.
hashtable entries for tuples that are found only in the second input: they
can never contribute to the output. Furthermore, this implies that the
planner should endeavor to put first the smaller (in number of groups) input
relation for an INTERSECT. Implement that, and upgrade prepunion's estimation
of the number of rows returned by setops so that there's some amount of sanity
in the estimate of which one is smaller.
This completes my project of improving usage of hashing for duplicate
elimination (aggregate functions with DISTINCT remain undone, but that's
for some other day).
As with the previous patches, this means we can INTERSECT/EXCEPT on datatypes
that can hash but not sort, and it means that INTERSECT/EXCEPT without ORDER
BY are no longer certain to produce sorted output.
but seem like a separate patch since most of the remaining work is on the
executor side.) I took the opportunity to push selection of the grouping
operators for set operations into the parser where it belongs. Otherwise this
is just a small exercise in making prepunion.c consider both alternatives.
As with the recent DISTINCT patch, this means we can UNION on datatypes that
can hash but not sort, and it means that UNION without ORDER BY is no longer
certain to produce sorted output.
as methods for implementing the DISTINCT step. This eliminates the former
performance gap between DISTINCT and GROUP BY, and also makes it possible
to do SELECT DISTINCT on datatypes that only support hashing not sorting.
SELECT DISTINCT ON is still always implemented by sorting; it would take
executor changes to support hashing that, and it's not clear it's worth
the trouble.
This is a release-note-worthy incompatibility from previous PG versions,
since SELECT DISTINCT can no longer be counted on to deliver sorted output
without explicitly saying ORDER BY. (Anyone who can't cope with that
can consider turning off enable_hashagg.)
Several regression test queries needed to have ORDER BY added to preserve
stable output order. I fixed the ones that manifested here, but there
might be some other cases that show up on other platforms.
as per my recent proposal:
1. Fold SortClause and GroupClause into a single node type SortGroupClause.
We were already relying on them to be struct-equivalent, so using two node
tags wasn't accomplishing much except to get in the way of comparing items
with equal().
2. Add an "eqop" field to SortGroupClause to carry the associated equality
operator. This is cheap for the parser to get at the same time it's looking
up the sort operator, and storing it eliminates the need for repeated
not-so-cheap lookups during planning. In future this will also let us
represent GROUP/DISTINCT operations on datatypes that have hash opclasses
but no btree opclasses (ie, they have equality but no natural sort order).
The previous representation simply didn't work for that, since its only
indicator of comparison semantics was a sort operator.
3. Add a hasDistinctOn boolean to struct Query to explicitly record whether
the distinctClause came from DISTINCT or DISTINCT ON. This allows removing
some complicated and not 100% bulletproof code that attempted to figure
that out from the distinctClause alone.
This patch doesn't in itself create any new capability, but it's necessary
infrastructure for future attempts to use hash-based grouping for DISTINCT
and UNION/INTERSECT/EXCEPT.
to represent DISTINCT or DISTINCT ON. This gets rid of a longstanding
annoyance that a view or rule using SELECT DISTINCT will be dumped out
with an overspecified ORDER BY list, and is one small step along the way
to decoupling DISTINCT and ORDER BY enough so that hash-based implementation
of DISTINCT will be possible. In passing, improve transformDistinctClause
so that it doesn't reject duplicate DISTINCT ON items, as was reported by
Steve Midgley a couple weeks ago.
filter to be used when INSERT or SELECT INTO has a plan that returns raw
disk tuples. The virtual-tuple-slot optimizations that were put in place
awhile ago mean that ExecInsert has to do ExecMaterializeSlot, and that
already copies the tuple if it's raw (and does so more efficiently than
a junk filter, too). So get rid of that logic. This in turn means that
we can throw away ExecMayReturnRawTuples, which wasn't used for any other
purpose, and was always a kluge anyway.
In passing, move a couple of SELECT-INTO-specific fields out of EState
and into the private state of the SELECT INTO DestReceiver, as was foreseen
in an old comment there. Also make intorel_receive use ExecMaterializeSlot
not ExecCopySlotTuple, for consistency with ExecInsert and to possibly save
a tuple copy step in some cases.
so long as all the trailing arguments are of the same (non-array) type.
The function receives them as a single array argument (which is why they
have to all be the same type).
It might be useful to extend this facility to aggregates, but this patch
doesn't do that.
This patch imposes a noticeable slowdown on function lookup --- a follow-on
patch will fix that by adding a redundant column to pg_proc.
Pavel Stehule
corresponding struct definitions. This allows other headers to avoid including
certain highly-loaded headers such as rel.h and relscan.h, instead using just
relcache.h, heapam.h or genam.h, which are more lightweight and thus cause less
unnecessary dependencies.
sequence to be reset to its original starting value. This requires adding the
original start value to the set of parameters (columns) of a sequence object,
which is a user-visible change with potential compatibility implications;
it also forces initdb.
Also add hopefully-SQL-compatible RESTART/CONTINUE IDENTITY options to
TRUNCATE TABLE. RESTART IDENTITY executes ALTER SEQUENCE RESTART for all
sequences "owned by" any of the truncated relations. CONTINUE IDENTITY is
a no-op option.
Zoltan Boszormenyi
as those for inherited columns; that is, it's no longer allowed for a child
table to not have a check constraint matching one that exists on a parent.
This satisfies the principle of least surprise (rows selected from the parent
will always appear to meet its check constraints) and eliminates some
longstanding bogosity in pg_dump, which formerly had to guess about whether
check constraints were really inherited or not.
The implementation involves adding conislocal and coninhcount columns to
pg_constraint (paralleling attislocal and attinhcount in pg_attribute)
and refactoring various ALTER TABLE actions to be more like those for
columns.
Alex Hunsaker, Nikhil Sontakke, Tom Lane
output is not of the same type that's needed for the IN comparison (ie,
where the parser inserted an implicit coercion above the subselect result).
We should record the coerced expression, not just a raw Var referencing
the subselect output, as the quantity that needs to be unique-ified if
we choose to implement the IN as Unique followed by a plain join.
As of 8.3 this error was causing crashes, as seen in bug #4113 from Javier
Hernandez, because the executor was being told to hash or sort the raw
subselect output column using operators appropriate to the coerced type.
In prior versions there was no crash because the executor chose the
hash or sort operators for itself based on the column type it saw.
However, that's still not really right, because what's unique for one data
type might not be unique for another. In corner cases we could get multiple
outputs of a row that should appear only once, as demonstrated by the
regression test case included in this commit.
However, this patch doesn't apply cleanly to 8.2 or before, and the code
involved has shifted enough over time that I'm hesitant to try to back-patch.
Given the lack of complaints from the field about such corner cases, I think
the bug may not be important enough to risk breaking other things with a
back-patch.
"consistent" functions, and remove pg_amop.opreqcheck, as per recent
discussion. The main immediate benefit of this is that we no longer need
8.3's ugly hack of requiring @@@ rather than @@ to test weight-using tsquery
searches on GIN indexes. In future it should be possible to optimize some
other queries better than is done now, by detecting at runtime whether the
index match is exact or not.
Tom Lane, after an idea of Heikki's, and with some help from Teodor.
no particular need to do get_op_opfamily_properties() while building an
indexscan plan. Postpone that lookup until executor start. This simplifies
createplan.c a lot more than it complicates nodeIndexscan.c, and makes things
more uniform since we already had to do it that way for RowCompare
expressions. Should be a bit faster too, at least for plans that aren't
re-used many times, since we avoid palloc'ing and perhaps copying the
intermediate list data structure.
indexscan always occurs in one call, and the results are returned in a
TIDBitmap instead of a limited-size array of TIDs. This should improve
speed a little by reducing AM entry/exit overhead, and it is necessary
infrastructure if we are ever to support bitmap indexes.
In an only slightly related change, add support for TIDBitmaps to preserve
(somewhat lossily) the knowledge that particular TIDs reported by an index
need to have their quals rechecked when the heap is visited. This facility
is not really used yet; we'll need to extend the forced-recheck feature to
plain indexscans before it's useful, and that hasn't been coded yet.
The intent is to use it to clean up 8.3's horrid @@@ kluge for text search
with weighted queries. There might be other uses in future, but that one
alone is sufficient reason.
Heikki Linnakangas, with some adjustments by me.
knowledge up through any joins it participates in. We were doing that already
in some special cases but not in the general case. Also, defend against zero
row estimates for the input relations in cost_mergejoin --- this fix may have
eliminated the only scenario in which that can happen, but be safe. Per
report from Alex Solovey.
directly to all the member expressions, instead of the previous implementation
where the ARRAY[] constructor would infer a common element type and then we'd
coerce the finished array after the fact. This has a number of benefits,
one being that we can allow an empty ARRAY[] construct so long as its
element type is specified by such a cast.
Brendan Jurd, minor fixes by me.
linear search when checking child-transaction XIDs. This makes for an
important speedup in transactions that have large numbers of children,
as in a recent example from Craig Ringer. We can also get rid of an
ugly kluge that represented lists of TransactionIds as lists of OIDs.
Heikki Linnakangas
tablespace permissions failures when copying an index that is in the
database's default tablespace. A side-effect of the change is that explicitly
specifying the default tablespace no longer triggers a permissions check;
this is not how it was done in pre-8.3 releases but is argued to be more
consistent. Per bug #3921 from Andrew Gilligan. (Note: I argued in the
subsequent discussion that maybe LIKE shouldn't copy index tablespaces
at all, but since no one indicated agreement with that idea, I've refrained
from doing it.)
clauseless joins of relations that have unexploited join clauses. Rather
than looking at every other base relation in the query, the correct thing is
to examine the other relations in the "initial_rels" list of the current
make_rel_from_joinlist() invocation, because those are what we actually have
the ability to join against. This might be a subset of the whole query in
cases where join_collapse_limit or from_collapse_limit or full joins have
prevented merging the whole query into a single join problem. This is a bit
untidy because we have to pass those rels down through a new PlannerInfo
field, but it's necessary. Per bug #3865 from Oleg Kharin.
of poorer planning in 8.3 than 8.2:
1. After pushing a constant across an outer join --- ie, given
"a LEFT JOIN b ON (a.x = b.y) WHERE a.x = 42", we can deduce that b.y is
sort of equal to 42, in the sense that we needn't fetch any b rows where
it isn't 42 --- loop to see if any additional deductions can be made.
Previous releases did that by recursing, but I had mistakenly thought that
this was no longer necessary given the EquivalenceClass machinery.
2. Allow pushing constants across outer join conditions even if the
condition is outerjoin_delayed due to a lower outer join. This is safe
as long as the condition is strict and we re-test it at the upper join.
3. Keep the outer-join clause even if we successfully push a constant
across it. This is *necessary* in the outerjoin_delayed case, but
even in the simple case, it seems better to do this to ensure that the
join search order heuristics will consider the join as reasonable to
make. Mark such a clause as having selectivity 1.0, though, since it's
not going to eliminate very many rows after application of the constant
condition.
4. Tweak have_relevant_eclass_joinclause to report that two relations
are joinable when they have vars that are equated to the same constant.
We won't actually generate any joinclause from such an EquivalenceClass,
but again it seems that in such a case it's a good idea to consider
the join as worth costing out.
5. Fix a bug in select_mergejoin_clauses that was exposed by these
changes: we have to reject candidate mergejoin clauses if either side was
equated to a constant, because we can't construct a canonical pathkey list
for such a clause. This is an implementation restriction that might be
worth fixing someday, but it doesn't seem critical to get it done for 8.3.
the two join variables at both ends: not only trailing rows that need not be
scanned because there cannot be a match on the other side, but initial rows
that will be scanned without possibly having a match. This allows a more
realistic estimate of startup cost to be made, per recent pgsql-performance
discussion. In passing, fix a couple of bugs that had crept into
mergejoinscansel: it was not quite up to speed for the task of estimating
descending-order scans, which is a new requirement in 8.3.
constraint status of copied indexes (bug #3774), as well as various other
small bugs such as failure to pstrdup when needed. Allow INCLUDING INDEXES
indexes to be merged with identical declared indexes (perhaps not real useful,
but the code is there and having it not apply to LIKE indexes seems pretty
unorthogonal). Avoid useless work in generateClonedIndexStmt(). Undo some
poorly chosen API changes, and put a couple of routines in modules that seem
to be better places for them.
but no database changes have been made since the last CommandCounterIncrement.
This should result in a significant improvement in the number of "commands"
that can typically be performed within a transaction before hitting the 2^32
CommandId size limit. In particular this buys back (and more) the possible
adverse consequences of my previous patch to fix plan caching behavior.
The implementation requires tracking whether the current CommandCounter
value has been "used" to mark any tuples. CommandCounter values stored into
snapshots are presumed not to be used for this purpose. This requires some
small executor changes, since the executor used to conflate the curcid of
the snapshot it was using with the command ID to mark output tuples with.
Separating these concepts allows some small simplifications in executor APIs.
Something for the TODO list: look into having CommandCounterIncrement not do
AcceptInvalidationMessages. It seems fairly bogus to be doing it there,
but exactly where to do it instead isn't clear, and I'm disinclined to mess
with asynchronous behavior during late beta.
opfuncid of an OpExpr initially, considering that it has the information
at hand already. We'll still treat opfuncid as a cache rather than a
guaranteed-valid value, but this change saves one more syscache lookup
in the normal code path.
predictable manner; in particular that if you say ORDER BY output-column-ref,
it will in fact sort by that specific column even if there are multiple
syntactic matches. An example is
SELECT random() AS a, random() AS b FROM ... ORDER BY b, a;
While the use-case for this might be a bit debatable, it worked as expected
in earlier releases, so we should preserve the behavior for 8.3. Per my
recent proposal.
While at it, fix convert_subquery_pathkeys() to handle RelabelType stripping
in both directions; it needs this for the same reasons make_sort_from_pathkeys
does.
in corner cases such as re-fetching a just-deleted row. We may be able to
relax this someday, but let's find out how many people really care before
we invest a lot of work in it. Per report from Heikki and subsequent
discussion.
While in the neighborhood, make the combination of INSENSITIVE and FOR UPDATE
throw an error, since they are semantically incompatible. (Up to now we've
accepted but just ignored the INSENSITIVE option of DECLARE CURSOR.)
then-delete on the current cursor row. The basic fix is that nodeTidscan.c
has to apply heap_get_latest_tid() to the current-scan-TID obtained from the
cursor query; this ensures we get the latest row version to work with.
However, since that only works if the query plan is a TID scan, we also have
to hack the planner to make sure only that type of plan will be selected.
(Formerly, the planner might decide to apply a seqscan if the table is very
small. This change is probably a Good Thing anyway, since it's hard to see
how a seqscan could really win.) That means the execQual.c code to support
CurrentOfExpr as a regular expression type is dead code, so replace it with
just an elog(). Also, add regression tests covering these cases. Note
that the added tests expose the fact that re-fetching an updated row
misbehaves if the cursor used FOR UPDATE. That's an independent bug that
should be fixed later. Per report from Dharmendra Goyal.
a relation as a reason to invalidate a plan when the relation changes. This
handles scenarios such as dropping/recreating a sequence that is referenced by
nextval('seq') in a cached plan. Rather than teach plancache.c all about
digging through plan trees to find regclass Consts, we charge the planner's
setrefs.c with making a list of the relation OIDs on which each plan depends.
That way the list can be built cheaply during a plan tree traversal that has
to happen anyway. Per bug #3662 and subsequent discussion.
columns, and the new version can be stored on the same heap page, we no longer
generate extra index entries for the new version. Instead, index searches
follow the HOT-chain links to ensure they find the correct tuple version.
In addition, this patch introduces the ability to "prune" dead tuples on a
per-page basis, without having to do a complete VACUUM pass to recover space.
VACUUM is still needed to clean up dead index entries, however.
Pavan Deolasee, with help from a bunch of other people.
null::char(3) to a simple Const node. (It already worked for non-null values,
but not when we skipped evaluation of a strict coercion function.) This
prevents loss of typmod knowledge in situations such as exhibited in bug
#3598. Unfortunately there seems no good way to fix that bug in 8.1 and 8.2,
because they simply don't carry a typmod for a plain Const node.
In passing I made all the other callers of makeNullConst supply "real" typmod
values too, though I think it probably doesn't matter anywhere else.
(Actually, it works as a plain statement too, but I didn't document that
because it seems a bit useless.) Unify VariableResetStmt with
VariableSetStmt, and clean up some ancient cruft in the representation of
same.
sets for outer joins, in the light of bug #3588 and additional thought and
experimentation. The original methodology was fatally flawed for nests of
more than two outer joins: it got the relationships between adjacent joins
right, but didn't always come to the right conclusions about whether a join
could be interchanged with one two or more levels below it. This was largely
caused by a mistaken idea that we should use the min_lefthand + min_righthand
sets of a sub-join as the minimum left or right input set of an upper join
when we conclude that the sub-join can't commute with the upper one. If
there's a still-lower join that the sub-join *can* commute with, this method
led us to think that that one could commute with the topmost join; which it
can't. Another problem (not directly connected to bug #3588) was that
make_outerjoininfo's processing-order-dependent method for enforcing outer
join identity #3 didn't work right: if we decided that join A could safely
commute with lower join B, we dropped all information about sub-joins under B
that join A could perhaps not safely commute with, because we removed B's
entire min_righthand from A's.
To fix, make an explicit computation of all inner join combinations that occur
below an outer join, and add to that the full syntactic relsets of any lower
outer joins that we determine it can't commute with. This method gives much
more direct enforcement of the outer join rearrangement identities, and it
turns out not to cost a lot of additional bookkeeping.
Thanks to Richard Harris for the bug report and test case.
This prevents needing to do complex and poorly-defined updates of the
mapping table if the new parser has different token types than the old.
Per discussion.
Oleg Bartunov and Teodor Sigaev, but I did a lot of editorializing,
so anything that's broken is probably my fault.
Documentation is nonexistent as yet, but let's land the patch so we can
get some portability testing done.
are not one of the query's defined result relations, but nonetheless have
triggers fired against them while the query is active. This was formerly
impossible but can now occur because of my recent patch to fix the firing
order for RI triggers. Caching a ResultRelInfo avoids duplicating work by
repeatedly opening and closing the same relation, and also allows EXPLAIN
ANALYZE to "see" and report on these extra triggers. Use the same mechanism
to cache open relations when firing deferred triggers at transaction shutdown;
this replaces the former one-element-cache strategy used in that case, and
should improve performance a bit when there are deferred triggers on a number
of relations.
child memory contexts is indented two spaces to the right of its
parent context. This should make it easier to deduce the memory
context hierarchy from the output of MemoryContextStats().
(which now deals only in optimizable statements), and put that code
into a new file parser/parse_utilcmd.c. This helps clarify and enforce
the design rule that utility statements shouldn't be processed during
the regular parse analysis phase; all interpretation of their meaning
should happen after they are given to ProcessUtility to execute.
(We need this because we don't retain any locks for a utility statement
that's in a plan cache, nor have any way to detect that it's stale.)
We are also able to simplify the API for parse_analyze() and related
routines, because they will now always return exactly one Query structure.
In passing, fix bug #3403 concerning trying to add a serial column to
an existing temp table (this is largely Heikki's work, but we needed
all that restructuring to make it safe).
with a plpgsql-defined cursor. The underlying mechanism for this is that the
main SQL engine will now take "WHERE CURRENT OF $n" where $n is a refcursor
parameter. Not sure if we should document that fact or consider it an
implementation detail. Per discussion with Pavel Stehule.
Along the way, allow FOR UPDATE in non-WITH-HOLD cursors; there may once
have been a reason to disallow that, but it seems to work now, and it's
really rather necessary if you want to select a row via a cursor and then
update it in a concurrent-safe fashion.
Original patch by Arul Shaji, rather heavily editorialized by Tom Lane.
from the other string-category types; this eliminates a lot of surprising
interpretations that the parser could formerly make when there was no directly
applicable operator.
Create a general mechanism that supports casts to and from the standard string
types (text,varchar,bpchar) for *every* datatype, by invoking the datatype's
I/O functions. These new casts are assignment-only in the to-string direction,
explicit-only in the other, and therefore should create no surprising behavior.
Remove a bunch of thereby-obsoleted datatype-specific casting functions.
The "general mechanism" is a new expression node type CoerceViaIO that can
actually convert between *any* two datatypes if their external text
representations are compatible. This is more general than needed for the
immediate feature, but might be useful in plpgsql or other places in future.
This commit does nothing about the issue that applying the concatenation
operator || to non-text types will now fail, often with strange error messages
due to misinterpreting the operator as array concatenation. Since it often
(not always) worked before, we should either make it succeed or at least give
a more user-friendly error; but details are still under debate.
Peter Eisentraut and Tom Lane
index key columns always have the type expected by the index's associated
operators, ie, we add RelabelType nodes when dealing with binary-compatible
index opclasses. This is needed to get varchar indexes to play nicely with
the new EquivalenceClass machinery, as per recent gripe from Josh Berkus that
CVS HEAD was failing to match a varchar index column to a constant restriction
in the query.
It seems likely that this change will allow removal of a lot of ugly ad-hoc
RelabelType-stripping that the planner has traditionally done while matching
expressions to other expressions, but I'll worry about that some other day.
in cases where a sub-SELECT inserts a WHERE clause between two outer joins,
that clause may prevent us from re-ordering the two outer joins. The code
was considering only the joins' own ON-conditions in determining reordering
safety, which is not good enough. Add a "delay_upper_joins" flag to
OuterJoinInfo to flag that we have detected such a clause and higher-level
outer joins shouldn't be permitted to commute with this one. (This might
seem overly coarse, but given the current rules for OJ reordering, it's
sufficient AFAICT.)
The failure case is actually pretty narrow: it needs a WHERE clause within
the RHS of a left join that checks the RHS of a lower left join, but is not
strict for that RHS (else we'd have simplified the lower join to a plain
join). Even then no failure will be manifest unless the planner chooses to
rearrange the join order.
Per bug report from Adam Terrey.
cheapest-startup-cost innerjoin indexscans, and make joinpath.c consider
both of these (when different) as the inside of a nestloop join. The
original design was based on the assumption that indexscan paths always
have negligible startup cost, and so total cost is the only important
figure of merit; an assumption that's obviously broken by bitmap
indexscans. This oversight could lead to choosing poor plans in cases
where fast-start behavior is more important than total cost, such as
LIMIT and IN queries. 8.1-vintage brain fade exposed by an example from
Chuck D.
is using mark/restore but not rewind or backward-scan capability. Insert a
materialize plan node between a mergejoin and its inner child if the inner
child is a sort that is expected to spill to disk. The materialize shields
the sort from the need to do mark/restore and thereby allows it to perform
its final merge pass on-the-fly; while the materialize itself is normally
cheap since it won't spill to disk unless the number of tuples with equal
key values exceeds work_mem.
Greg Stark, with some kibitzing from Tom Lane.
recompute the limit/offset immediately, so that the updated values are
available when the child's ReScan function is invoked. Add a regression
test for this, too. Bug is new in HEAD (due to the bounded-sorting patch)
so no need for back-patch.
I did not do anything about merging this signaling with chgParam processing,
but if we were to do that we'd still need to compute the updated values
at this point rather than during the first ProcNode call.
Per observation and test case from Greg Stark, though I didn't use his patch.
need be returned. We keep a heap of the current best N tuples and sift-up
new tuples into it as we scan the input. For M input tuples this means
only about M*log(N) comparisons instead of M*log(M), not to mention a lot
less workspace when N is small --- avoiding spill-to-disk for large M
is actually the most attractive thing about it. Patch includes planner
and executor support for invoking this facility in ORDER BY ... LIMIT
queries. Greg Stark, with some editorialization by moi.
types of unspecified parameters when submitted via extended query protocol.
This worked in 8.2 but I had broken it during plancache changes. DECLARE
CURSOR is now treated almost exactly like a plain SELECT through parse
analysis, rewrite, and planning; only just before sending to the executor
do we divert it away to ProcessUtility. This requires a special-case check
in a number of places, but practically all of them were already special-casing
SELECT INTO, so it's not too ugly. (Maybe it would be a good idea to merge
the two by treating IntoClause as a form of utility statement? Not going to
worry about that now, though.) That approach doesn't work for EXPLAIN,
however, so for that I punted and used a klugy solution of running parse
analysis an extra time if under extended query protocol.
is in progress on the same hashtable. This seems the least invasive way to
fix the recently-recognized problem that a split could cause the scan to
visit entries twice or (with much lower probability) miss them entirely.
The only field-reported problem caused by this is the "failed to re-find
shared lock object" PANIC in COMMIT PREPARED reported by Michel Dorochevsky,
which was caused by multiply visited entries. However, it seems certain
that mdsync() is vulnerable to missing required fsync's due to missed
entries, and I am fearful that RelationCacheInitializePhase2() might be at
risk as well. Because of that and the generalized hazard presented by this
bug, back-patch all the supported branches.
Along the way, fix pg_prepared_statement() and pg_cursor() to not assume
that the hashtables they are examining will stay static between calls.
This is risky regardless of the newly noted dynahash problem, because
hash_seq_search() has never promised to cope with deletion of table entries
other than the just-returned one. There may be no bug here because the only
supported way to call these functions is via ExecMakeTableFunctionResult()
which will cycle them to completion before doing anything very interesting,
but it seems best to get rid of the assumption. This affects 8.2 and HEAD
only, since those functions weren't there earlier.
RESET SESSION, RESET PLANS, and RESET TEMP are now DISCARD ALL,
DISCARD PLANS, and DISCARD TEMP, respectively. This is to avoid
confusion with the pre-existing RESET variants: the DISCARD
commands are not actually similar to RESET. Patch from Marko
Kreen, with some minor editorialization.
are mostly excluded by constraints: do the CE test a bit earlier to save
some adjust_appendrel_attrs() work on excluded children, and arrange to
use array indexing rather than rt_fetch() to fetch RTEs in the main body
of the planner. The latter is something I'd wanted to do for awhile anyway,
but seeing list_nth_cell() as 35% of the runtime gets one's attention.
access to the planner's cursor-related planning options, and provide new
FETCH/MOVE routines that allow access to the full power of those commands.
Small refactoring of planner(), pg_plan_query(), and pg_plan_queries()
APIs to make it convenient to pass the planning options down from SPI.
This is the core-code portion of Pavel Stehule's patch for scrollable
cursor support in plpgsql; I'll review and apply the plpgsql changes
separately.
reviewed by Neil Conway. This patch adds the following DDL command
variants: RESET SESSION, RESET TEMP, RESET PLANS, CLOSE ALL, and
DEALLOCATE ALL. RESET SESSION is intended for use by connection
pool software and the like, in order to reset a client session
to something close to its initial state.
Note that while most of these command variants can be executed
inside a transaction block (but are not transaction-aware!),
RESET SESSION cannot. While this is inconsistent, it is intended
to catch programmer mistakes: RESET SESSION in an open transaction
block is probably unintended.
seen by code inspecting the expression. The best way to do this seems
to be to drop the original representation as a function invocation, and
instead make a special expression node type that represents applying
the element-type coercion function to each array element. In this way
the element function is exposed and will be checked for volatility.
Per report from Guillaume Smet.
rules to be defined with different, per session controllable, behaviors
for replication purposes.
This will allow replication systems like Slony-I and, as has been stated
on pgsql-hackers, other products to control the firing mechanism of
triggers and rewrite rules without modifying the system catalog directly.
The firing mechanisms are controlled by a new superuser-only GUC
variable, session_replication_role, together with a change to
pg_trigger.tgenabled and a new column pg_rewrite.ev_enabled. Both
columns are a single char data type now (tgenabled was a bool before).
The possible values in these attributes are:
'O' - Trigger/Rule fires when session_replication_role is "origin"
(default) or "local". This is the default behavior.
'D' - Trigger/Rule is disabled and fires never
'A' - Trigger/Rule fires always regardless of the setting of
session_replication_role
'R' - Trigger/Rule fires when session_replication_role is "replica"
The GUC variable can only be changed as long as the system does not have
any cached query plans. This will prevent changing the session role and
accidentally executing stored procedures or functions that have plans
cached that expand to the wrong query set due to differences in the rule
firing semantics.
The SQL syntax for changing a triggers/rules firing semantics is
ALTER TABLE <tabname> <when> TRIGGER|RULE <name>;
<when> ::= ENABLE | ENABLE ALWAYS | ENABLE REPLICA | DISABLE
psql's \d command as well as pg_dump are extended in a backward
compatible fashion.
Jan
available information about the typmod of an expression; namely, Const,
ArrayRef, ArrayExpr, and EXPR and ARRAY SubLinks. In the ArrayExpr and
SubLink cases it wasn't really the data structure's fault, but exprTypmod()
being lazy. This seems like a good idea in view of the expected increase in
typmod usage from Teodor's work to allow user-defined types to have typmods.
In particular this responds to the concerns we had about eliminating the
special-purpose hack that exprTypmod() used to have for BPCHAR Consts.
We can now tell whether or not such a Const has been cast to a specific
length, and report or display properly if so.
initdb forced due to changes in stored rules.
module and teach PREPARE and protocol-level prepared statements to use it.
In service of this, rearrange utility-statement processing so that parse
analysis does not assume table schemas can't change before execution for
utility statements (necessary because we don't attempt to re-acquire locks
for utility statements when reusing a stored plan). This requires some
refactoring of the ProcessUtility API, but it ends up cleaner anyway,
for instance we can get rid of the QueryContext global.
Still to do: fix up SPI and related code to use the plan cache; I'm tempted to
try to make SQL functions use it too. Also, there are at least some aspects
of system state that we want to ensure remain the same during a replan as in
the original processing; search_path certainly ought to behave that way for
instance, and perhaps there are others.
parent query's EState. Now that there's a single flat rangetable for both
the main plan and subplans, there's no need anymore for a separate EState,
and removing it allows cleaning up some crufty code in nodeSubplan.c and
nodeSubqueryscan.c. Should be a tad faster too, although any difference
will probably be hard to measure. This is the last bit of subsidiary
mop-up work from changing to a flat rangetable.
useless substructure for its RangeTblEntry nodes. (I chose to keep using the
same struct node type and just zero out the link fields for unneeded info,
rather than making a separate ExecRangeTblEntry type --- it seemed too
fragile to have two different rangetable representations.)
Along the way, put subplans into a list in the toplevel PlannedStmt node,
and have SubPlan nodes refer to them by list index instead of direct pointers.
Vadim wanted to do that years ago, but I never understood what he was on about
until now. It makes things a *whole* lot more robust, because we can stop
worrying about duplicate processing of subplans during expression tree
traversals. That's been a constant source of bugs, and it's finally gone.
There are some consequent simplifications yet to be made, like not using
a separate EState for subplans in the executor, but I'll tackle that later.
storing mostly-redundant Query trees in prepared statements, portals, etc.
To replace Query, a new node type called PlannedStmt is inserted by the
planner at the top of a completed plan tree; this carries just the fields of
Query that are still needed at runtime. The statement lists kept in portals
etc. now consist of intermixed PlannedStmt and bare utility-statement nodes
--- no Query. This incidentally allows us to remove some fields from Query
and Plan nodes that shouldn't have been there in the first place.
Still to do: simplify the execution-time range table; at the moment the
range table passed to the executor still contains Query trees for subqueries.
initdb forced due to change of stored rules.
this code was last gone over, there wasn't really any alternative to
globals because we didn't have the PlannerInfo struct being passed all
through the planner code. Now that we do, we can restructure things
to avoid non-reentrancy. I'm fooling with this because otherwise I'd
have had to add another global variable for the planned compact
range table list.
plan nodes, so that the executor does not need to get these items from
the range table at runtime. This will avoid needing to include these
fields in the compact range table I'm expecting to make the executor use.
JOIN quals, just like WHERE quals, even if they reference every one of the
join's relations. Now that we can reorder outer and inner joins, it's
possible for such a qual to end up being assigned to an outer join plan node,
and we mustn't have it treated as a join qual rather than a filter qual for
the node. (If it were, the join could produce null-extended rows that it
shouldn't.) Per bug report from Pelle Johansson.
that aren't turned into true joins). Since this is the last missing bit of
infrastructure, go ahead and fill out the hash integer_ops and float_ops
opfamilies with cross-type operators. The operator family project is now
DONE ... er, except for documentation ...
observe the xmloption.
Reorganize the representation of the XML option in the parse tree and the
API to make it easier to manage and understand.
Add regression tests for parsing back XML expressions.
FAMILY; and add FAMILY option to CREATE OPERATOR CLASS to allow adding a
class to a pre-existing family. Per previous discussion. Man, what a
tedious lot of cutting and pasting ...
which I had removed in the first cut of the EquivalenceClass rewrite to
simplify that patch a little. But it's still important --- in a four-way
join problem mergejoinscansel() was eating about 40% of the planning time
according to gprof. Also, improve the EquivalenceClass code to re-use
join RestrictInfos rather than generating fresh ones for each join
considered. This saves some memory space but more importantly improves
the effectiveness of caching planning info in RestrictInfos.
representation of equivalence classes of variables. This is an extensive
rewrite, but it brings a number of benefits:
* planner no longer fails in the presence of "incomplete" operator families
that don't offer operators for every possible combination of datatypes.
* avoid generating and then discarding redundant equality clauses.
* remove bogus assumption that derived equalities always use operators
named "=".
* mergejoins can work with a variety of sort orders (e.g., descending) now,
instead of tying each mergejoinable operator to exactly one sort order.
* better recognition of redundant sort columns.
* can make use of equalities appearing underneath an outer join.
which comparison operators to use for plan nodes involving tuple comparison
(Agg, Group, Unique, SetOp). Formerly the executor looked up the default
equality operator for the datatype, which was really pretty shaky, since it's
possible that the data being fed to the node is sorted according to some
nondefault operator class that could have an incompatible idea of equality.
The planner knows what it has sorted by and therefore can provide the right
equality operator to use. Also, this change moves a couple of catalog lookups
out of the executor and into the planner, which should help startup time for
pre-planned queries by some small amount. Modify the planner to remove some
other cavalier assumptions about always being able to use the default
operators. Also add "nulls first/last" info to the Plan node for a mergejoin
--- neither the executor nor the planner can cope yet, but at least the API is
in place.
per-column options for btree indexes. The planner's support for this is still
pretty rudimentary; it does not yet know how to plan mergejoins with
nondefault ordering options. The documentation is pretty rudimentary, too.
I'll work on improving that stuff later.
Note incompatible change from prior behavior: ORDER BY ... USING will now be
rejected if the operator is not a less-than or greater-than member of some
btree opclass. This prevents less-than-sane behavior if an operator that
doesn't actually define a proper sort ordering is selected.
involving HashAggregate over SubqueryScan (this is the known case, there
may well be more). The bug is only latent in releases before 8.2 since they
didn't try to access tupletable slots' descriptors during ExecDropTupleTable.
The least bogus fix seems to be to make subqueries share the parent query's
memory context, so that tupdescs they create will have the same lifespan as
those of the parent query. There are comments in the code envisioning going
even further by not having a separate child EState at all, but that will
require rethinking executor access to range tables, which I don't want to
tackle right now. Per bug report from Jean-Pierre Pelletier.
the XmlExpr code in various lists, use a representation that has some hope
of reverse-listing correctly (though it's still a de-escaping function
shy of correctness), generally try to make it look more like Postgres
coding conventions.
cases. Operator classes now exist within "operator families". While most
families are equivalent to a single class, related classes can be grouped
into one family to represent the fact that they are semantically compatible.
Cross-type operators are now naturally adjunct parts of a family, without
having to wedge them into a particular opclass as we had done originally.
This commit restructures the catalogs and cleans up enough of the fallout so
that everything still works at least as well as before, but most of the work
needed to actually improve the planner's behavior will come later. Also,
there are not yet CREATE/DROP/ALTER OPERATOR FAMILY commands; the only way
to create a new family right now is to allow CREATE OPERATOR CLASS to make
one by default. I owe some more documentation work, too. But that can all
be done in smaller pieces once this infrastructure is in place.
representing externally-supplied values, since the APIs that carry such
values only specify type not typmod. However, for PARAM_SUBLINK Params
it is handy to carry the typmod of the sublink's output column. This
is a much cleaner solution for the recently reported 'could not find
pathkey item to sort' and 'failed to find unique expression in subplan
tlist' bugs than my original 8.2-compatible patch. Besides, someday we
might want to support typmods for external parameters ...
by name on each and every row processed. Profiling suggests this may
buy a percent or two for simple UPDATE scenarios, which isn't huge,
but when it's so easy to get ...
in PITR scenarios. We now WAL-log the replacement of old XIDs with
FrozenTransactionId, so that such replacement is guaranteed to propagate to
PITR slave databases. Also, rather than relying on hint-bit updates to be
preserved, pg_clog is not truncated until all instances of an XID are known to
have been replaced by FrozenTransactionId. Add new GUC variables and
pg_autovacuum columns to allow management of the freezing policy, so that
users can trade off the size of pg_clog against the amount of freezing work
done. Revise the already-existing code that forces autovacuum of tables
approaching the wraparound point to make it more bulletproof; also, revise the
autovacuum logic so that anti-wraparound vacuuming is done per-table rather
than per-database. initdb forced because of changes in pg_class, pg_database,
and pg_autovacuum catalogs. Heikki Linnakangas, Simon Riggs, and Tom Lane.
the SQL spec, viz IS NULL is true if all the row's fields are null, IS NOT
NULL is true if all the row's fields are not null. The former coding got
this right for a limited number of cases with IS NULL (ie, those where it
could disassemble a ROW constructor at parse time), but was entirely wrong
for IS NOT NULL. Per report from Teodor.
I desisted from changing the behavior for arrays, since on closer inspection
it's not clear that there's any support for that in the SQL spec. This
probably needs more consideration.
tables in the query compete for cache space, not just the one we are
currently costing an indexscan for. This seems more realistic, and it
definitely will help in examples recently exhibited by Stefan
Kaltenbrunner. To get the total size of all the tables involved, we must
tweak the handling of 'append relations' a bit --- formerly we looked up
information about the child tables on-the-fly during set_append_rel_pathlist,
but it needs to be done before we start doing any cost estimation, so
push it into the add_base_rels_to_query scan.
that has parameters is always planned afresh for each Bind command,
treating the parameter values as constants in the planner. This removes
the performance penalty formerly often paid for using out-of-line
parameters --- with this definition, the planner can do constant folding,
LIKE optimization, etc. After a suggestion by Andrew@supernews.
can create or modify rules for the table. Do setRuleCheckAsUser() while
loading rules into the relcache, rather than when defining a rule. This
ensures that permission checks for tables referenced in a rule are done with
respect to the current owner of the rule's table, whereas formerly ALTER TABLE
OWNER would fail to update the permission checking for associated rules.
Removal of separate RULE privilege is needed to prevent various scenarios
in which a grantee of RULE privilege could effectively have any privilege
of the table owner. For backwards compatibility, GRANT/REVOKE RULE is still
accepted, but it doesn't do anything. Per discussion here:
http://archives.postgresql.org/pgsql-hackers/2006-04/msg01138.php
by abandoning the idea that it should say SERIAL in the dump. Instead,
dump serial sequences and column defaults just like regular ones.
Add a new backend command ALTER SEQUENCE OWNED BY to let pg_dump recreate
the sequence-to-column dependency that was formerly created "behind the
scenes" by SERIAL. This restores SERIAL to being truly "just a macro"
consisting of component operations that can be stated explicitly in SQL.
Furthermore, the new command allows sequence ownership to be reassigned,
so that old mistakes can be cleaned up.
Also, downgrade the OWNED-BY dependency from INTERNAL to AUTO, since there
is no longer any very compelling argument why the sequence couldn't be
dropped while keeping the column. (This forces initdb, to be sure the
right kinds of dependencies are in there.)
Along the way, add checks to prevent ALTER OWNER or SET SCHEMA on an
owned sequence; you can now only do this indirectly by changing the
owning table's owner or schema. This is an oversight in previous
releases, but probably not worth back-patching.
merely a matter of fixing the error check, since the underlying Portal
infrastructure already handles it. This in turn allows these statements
to be used in some existing plpgsql and plperl contexts, such as a
plpgsql FOR loop. Also, do some marginal code cleanup in places that
were being sloppy about distinguishing SELECT from SELECT INTO.
plpgsql support to come later. Along the way, convert execMain's
SELECT INTO support into a DestReceiver, in order to eliminate some ugly
special cases.
Jonah Harris and Tom Lane
same data type and same typmod, we show that typmod as the output
typmod, rather than generic -1. This responds to several complaints
over the past few years about UNIONs unexpectedly dropping length or
precision info.
that's shorter-lived than the expression state being evaluated in it really
doesn't work :-( --- we end up with fn_extra caches getting deleted while
still in use. Rather than abandon the notion of caching expression state
across domain_in calls altogether, I chose to make domain_in a bit cozier
with ExprContext. All we really need for evaluating variable-free
expressions is an ExprContext, not an EState, so I invented the notion of a
"standalone" ExprContext. domain_in can prevent resource leakages by doing
a ReScanExprContext on this rather than having to free it entirely; so we
can make the ExprContext have the same lifespan (and particularly the same
per_query memory context) as the expression state structs.
temporary context that can be reset when advancing to the next sublist.
This is faster and more thorough at recovering space than the previous
method; moreover it will do the right thing if something in the sublist
tries to register an expression context callback.
(e.g. "INSERT ... VALUES (...), (...), ...") and elsewhere as allowed
by the spec. (e.g. similar to a FROM clause subselect). initdb required.
Joe Conway and Tom Lane.
created in the bootstrap phase proper, rather than added after-the-fact
by initdb. This is cleaner than before because it allows us to retire the
undocumented ALTER TABLE ... CREATE TOAST TABLE command, but the real reason
I'm doing it is so that toast tables of shared catalogs will now have
predetermined OIDs. This will allow a reasonably clean solution to the
problem of locking tables before we load their relcache entries, to appear
in a forthcoming patch.
the opportunity to treat COUNT(*) as a zero-argument aggregate instead
of the old hack that equated it to COUNT(1); this is materially cleaner
(no more weird ANYOID cases) and ought to be at least a tiny bit faster.
Original patch by Sergey Koposov; review, documentation, simple regression
tests, pg_dump and psql support by moi.
eliminate unnecessary code, force initdb because stored rules change
(limit nodes are now supposed to be int8 not int4 expressions).
Update comments and error messages, which still all said 'integer'.
discussion (including making def_arg allow reserved words), add missed
opt_definition for UNIQUE case. Put the reloptions support code in a less
random place (I chose to make a new file access/common/reloptions.c).
Eliminate header inclusion creep. Make the index options functions safely
user-callable (seems like client apps might like to be able to test validity
of options before trying to make an index). Reduce overhead for normal case
with no options by allowing rd_options to be NULL. Fix some unmaintainably
klugy code, including getting rid of Natts_pg_class_fixed at long last.
Some stylistic cleanup too, and pay attention to keeping comments in sync
with code.
Documentation still needs work, though I did fix the omissions in
catalogs.sgml and indexam.sgml.
Open items:
There were a few tangentially related issues that have come up that I think
are TODOs. I'm likely to tackle one or two of these next so I'm interested in
hearing feedback on them as well.
. Constraints currently do not know anything about inheritance. Tom suggested
adding a coninhcount and conislocal like attributes have to track their
inheritance status.
. Foreign key constraints currently do not get copied to new children (and
therefore my code doesn't verify them). I don't think it would be hard to
add them and treat them like CHECK constraints.
. No constraints at all are copied to tables defined with LIKE. That makes it
hard to use LIKE to define new partitions. The standard defines LIKE and
specifically says it does not copy constraints. But the standard already has
an option called INCLUDING DEFAULTS; we could always define a non-standard
extension LIKE table INCLUDING CONSTRAINTS that gives the user the option to
request a copy including constraints.
. Personally, I think the whole attislocal thing is bunk. The decision about
whether to drop a column from children tables or not is something that
should be up to the user and trying to DWIM based on whether there was ever
a local definition or the column was acquired purely through inheritance is
hardly ever going to match up with user expectations.
. And of course there's the whole unique and primary key constraint issue. I
think to get any traction at all on this you have a prerequisite of a real
partitioned table implementation where the system knows what the partition
key is so it can recognize when it's a leading part of an index key.
Greg Stark
clauses containing no variables and no volatile functions. Such a clause
can be used as a one-time qual in a gating Result plan node, to suppress
plan execution entirely when it is false. Even when the clause is true,
putting it in a gating node wins by avoiding repeated evaluation of the
clause. In previous PG releases, query_planner() would do this for
pseudoconstant clauses appearing at the top level of the jointree, but
there was no ability to generate a gating Result deeper in the plan tree.
To fix it, get rid of the special case in query_planner(), and instead
process pseudoconstant clauses through the normal RestrictInfo qual
distribution mechanism. When a pseudoconstant clause is found attached to
a path node in create_plan(), pull it out and generate a gating Result at
that point. This requires special-casing pseudoconstants in selectivity
estimation and cost_qual_eval, but on the whole it's pretty clean.
It probably even makes the planner a bit faster than before for the normal
case of no pseudoconstants, since removing pull_constant_clauses saves one
useless traversal of the qual tree. Per gripe from Phil Frost.
tuple hash table entries. This addresses the problem previously noted
that use of a 'physical tlist' in the input scan node could bloat the
hash table entries far beyond what the planner expects. It's a better
answer than my previous thought of undoing the physical tlist optimization,
because we can also remove columns that are needed to compute the aggregate
functions but aren't part of the grouping column set.
that the Mackert-Lohmann formula applies across all the repetitions of the
nestloop, not just each scan independently. We use the M-L formula to
estimate the number of pages fetched from the index as well as from the table;
that isn't what it was designed for, but it seems reasonably applicable
anyway. This makes large numbers of repetitions look much cheaper than
before, which accords with many reports we've received of overestimation
of the cost of a nestloop. Also, change the index access cost model to
charge random_page_cost per index leaf page touched, while explicitly
not counting anything for access to metapage or upper tree pages. This
may all need tweaking after we get some field experience, but in simple
tests it seems to be giving saner results than before. The main thing
is to get the infrastructure in place to let cost_index() and amcostestimate
functions take repeated scans into account at all. Per my recent proposal.
Note: this patch changes pg_proc.h, but I did not force initdb because
the changes are basically cosmetic --- the system does not look into
pg_proc to decide how to call an index amcostestimate function, and
there's no way to call such a function from SQL at all.
support both FOR UPDATE and FOR SHARE in one command, as well as both
NOWAIT and normal WAIT behavior. The more general code is actually
simpler and cleaner.
not named ones, and replace linear searches of the list with array indexing.
The named-parameter support has been dead code for many years anyway,
and recent profiling suggests that the searching was costing a noticeable
amount of performance for complex queries.
CREATE AGGREGATE aggname (input_type) (parameter_list)
along with the old syntax where the input type was named in the parameter
list. This fits more naturally with the way that the aggregate is identified
in DROP AGGREGATE and other utility commands; furthermore it has a natural
extension to handle multiple-input aggregates, where the basetype-parameter
method would get ugly. In fact, this commit fixes the grammar and all the
utility commands to support multiple-input aggregates; but DefineAggregate
rejects it because the executor isn't fixed yet.
I didn't do anything about treating agg(*) as a zero-input aggregate instead
of artificially making it a one-input aggregate, but that should be considered
in combination with supporting multi-input aggregates.
The original coding stored the raw parser output (ColumnDef and TypeName
nodes) which was ugly, bulky, and wrong because it failed to create any
dependency on the referenced datatype --- and in fact would not track type
renamings and suchlike. Instead store a list of column type OIDs in the
RTE.
Also fix up general failure of recordDependencyOnExpr to do anything sane
about recording dependencies on datatypes. While there are many cases where
there will be an indirect dependency (eg if an operator returns a datatype,
the dependency on the operator is enough), we do have to record the datatype
as a separate dependency in examples like CoerceToDomain.
initdb forced because of change of stored rules.
during parse analysis, not only errors detected in the flex/bison stages.
This is per my earlier proposal. This commit includes all the basic
infrastructure, but locations are only tracked and reported for errors
involving column references, function calls, and operators. More could
be done later but this seems like a good set to start with. I've also
moved the ReportSyntaxErrorPosition logic out of psql and into libpq,
which should make it available to more people --- even within psql this
is an improvement because warnings weren't handled by ReportSyntaxErrorPosition.
not likely ever to be implemented seeing it's been removed from SQL2003.
This allows getting rid of the 'filter' version of yylex() that we had in
parser.c, which should save at least a few microseconds in parsing.
inheritance trees on-the-fly, which pretty well constrained us to considering
only one way of planning inheritance, expand inheritance sets during the
planner prep phase, and build a side data structure that can be consulted
later to find which RTEs are members of which inheritance sets. As proof of
concept, use the data structure to plan joins against inheritance sets more
efficiently: we can now use indexes on the set members in inner-indexscan
joins. (The generated plans could be improved further, but it'll take some
executor changes.) This data structure will also support handling UNION ALL
subqueries in the same way as inheritance sets, but that aspect of it isn't
finished yet.
Continue to support GRANT ON [TABLE] for sequences for backward
compatibility; issue warning for invalid sequence permissions.
[Backward compatibility warning message.]
Add USAGE permission for sequences that allows only currval() and
nextval(), not setval().
Mention object name in grant/revoke warnings because of possible
multi-object operations.
(previously we only did = and <> correctly). Also, allow row comparisons
with any operators that are in btree opclasses, not only those with these
specific names. This gets rid of a whole lot of indefensible assumptions
about the behavior of particular operators based on their names ... though
it's still true that IN and NOT IN expand to "= ANY". The patch adds a
RowCompareExpr expression node type, and makes some changes in the
representation of ANY/ALL/ROWCOMPARE SubLinks so that they can share code
with RowCompareExpr.
I have not yet done anything about making RowCompareExpr an indexable
operator, but will look at that soon.
initdb forced due to changes in stored rules.
Per my recent proposal. I ended up basing the implementation on the
existing mechanism for enforcing valid join orders of IN joins --- the
rules for valid outer-join orders are somewhat similar.
relation if it's already been locked by execMain.c as either a result
relation or a FOR UPDATE/SHARE relation. This avoids an extra trip to
the shared lock manager state. Per my suggestion yesterday.
it's worth probing the outer relation for emptiness before building the
hash table. To wit, if we're rescanning a join previously performed,
remember whether we found it nonempty the previous time, and don't bother
with the probe if it was nonempty. This buys back the performance lost
in examples like Mario Weilguni's.
ScalarArrayOpExpr when possible, that is, whenever there is an array type
for the values of the expression list. This completes the project I've
been working on to improve the speed of index searches with long IN lists,
as per discussion back in mid-October.
I did not force initdb, but until you do one you will see failures in the
"rules" regression test, because some of the standard system views use IN
and their compiled formats have changed.
"ctid IN (list)" will still work after we convert IN to ScalarArrayOpExpr.
Make some minor efficiency improvements while at it, such as ensuring that
multiple TIDs are fetched in physical heap order. And fix EXPLAIN so that
it shows what's really going on for a TID scan.
when we first read the page, rather than checking them one at a time.
This allows us to take and release the buffer content lock just once
per page, instead of once per tuple. Since it's a shared lock the
contention penalty for holding the lock longer shouldn't be too bad.
We can safely do this only when using an MVCC snapshot; else the
assumption that visibility won't change over time is uncool. Therefore
there are now two code paths depending on the snapshot type. I also
made the same change in nodeBitmapHeapscan.c, where it can be done always
because we only support MVCC snapshots for bitmap scans anyway.
Also make some incidental cleanups in the APIs of these functions.
Per a suggestion from Qingqing Zhou.
qualification when the underlying operator is indexable and useOr is true.
That is, indexkey op ANY (ARRAY[...]) is effectively translated into an
OR combination of one indexscan for each array element. This only works
for bitmap index scans, of course, since regular indexscans no longer
support OR'ing of scans. There are still some loose ends to clean up
before changing 'x IN (list)' to translate as a ScalarArrayOpExpr;
for instance predtest.c ought to be taught about it. But this gets the
basic functionality in place.
comment line where output as too long, and update typedefs for /lib
directory. Also fix case where identifiers were used as variable names
in the backend, but as typedefs in ecpg (favor the backend for
indenting).
Backpatch to 8.1.X.
process of dropping roles by dropping objects owned by them and privileges
granted to them, or giving the owned objects to someone else, through the
use of the data stored in the new pg_shdepend catalog.
Some refactoring of the GRANT/REVOKE code was needed, as well as ALTER OWNER
code. Further cleanup of code duplication in the GRANT code seems necessary.
Implemented by me after an idea from Tom Lane, who also provided various kind
of implementation advice.
Regression tests pass. Some tests for the new functionality are also added,
as well as rudimentary documentation.
sense and rename to "outerjoin_delayed" to more clearly reflect what it
means). I had decided that it was redundant in 8.1, but the folly of this
is exposed by a bug report from Sebastian Böck. The place where it's
needed is to prevent orindxpath.c from cherry-picking arms of an outer-join
OR clause to form a relation restriction that isn't actually legal to push
down to the relation scan level. There may be some legal cases that this
forbids optimizing, but we'd need much closer analysis to determine it.
slot of the topmost plan node when a trigger returns a modified tuple.
These appear to be the only places where a plan node's caller did not
treat the result slot as read-only, which is an assumption that nodeUnique
makes as of 8.1. Fixes trigger-vs-DISTINCT bug reported by Frank van Vugt.
inFromCl true, meaning that they will list out as explicit RTEs if they
are in a view or rule. Update comments about inFromCl to reflect the way
it's now actually used. Per recent discussion.
outer relation is empty did not work, per test case from Patrick Welche.
It tried to use nodeHashjoin.c's high-level mechanisms for fetching an
outer-relation tuple, but that code expected the hash table to be filled
already. As patched, the code failed in corner cases such as having no
outer-relation tuples for the first hash batch. Revert and rewrite.
so that the latter estimates the number of groups that grouping will
produce. This is needed because it is primarily query_planner that
makes the decision between fast-start and fast-finish plans, and in the
original coding it was unable to make more than a crude rule-of-thumb
choice when the query involved grouping. This revision helps us make
saner choices for queries like SELECT ... GROUP BY ... LIMIT, as in a
recent example from Mark Kirkwood. Also move the responsibility for
canonicalizing sort_pathkeys and group_pathkeys into query_planner;
this information has to be available anyway to support the first change,
and doing it this way lets us get rid of compare_noncanonical_pathkeys
entirely.
use these instead of its previous hack of changing pg_class.reltriggers.
Documentation is lacking, will add that later.
Patch by Satoshi Nagayasu, review and some extra work by Tom Lane.
Tom Lane
Bruce Momjian
Fujii Masao
Alvaro Herrera
Andrew Dunstan
Simon Riggs
Stephen Frost
Robert Haas
Heikki Linnakangas
Tatsuo Ishii
Noah Misch
Peter Eisentraut
Greg Stark
Kevin Grittner
Itagaki Takahiro
Magnus Hagander
Neil Conway
Jan Wieck
Joe Conway