Formerly we relied on checking after-the-fact to see if an expression
contained aggregates, window functions, or sub-selects when it shouldn't.
This is grotty, easily forgotten (indeed, we had forgotten to teach
DefineIndex about rejecting window functions), and none too efficient
since it requires extra traversals of the parse tree. To improve matters,
define an enum type that classifies all SQL sub-expressions, store it in
ParseState to show what kind of expression we are currently parsing, and
make transformAggregateCall, transformWindowFuncCall, and transformSubLink
check the expression type and throw error if the type indicates the
construct is disallowed. This allows removal of a large number of ad-hoc
checks scattered around the code base. The enum type is sufficiently
fine-grained that we can still produce error messages of at least the
same specificity as before.
Bringing these error checks together revealed that we'd been none too
consistent about phrasing of the error messages, so standardize the wording
a bit.
Also, rewrite checking of aggregate arguments so that it requires only one
traversal of the arguments, rather than up to three as before.
In passing, clean up some more comments left over from add_missing_from
support, and annotate some tests that I think are dead code now that that's
gone. (I didn't risk actually removing said dead code, though.)
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.
Rip out a regression test that doesn't play well with settings put in
place by the build farm, and rewrite the code in CheckIndexCompatible
in a hopefully more transparent style.
This gives up the "don't rewrite the index" behavior in a couple of
relatively unimportant cases, such as changing between an array type
and an unconstrained domain over that array type, in return for
making this code more future-proof.
Noah Misch
In the previous coding, a user could queue up for an AccessExclusiveLock
on a table they did not have permission to cluster, thus potentially
interfering with access by authorized users who got stuck waiting behind
the AccessExclusiveLock. This approach avoids that. cluster() has the
same permissions-checking requirements as REINDEX TABLE, so this commit
moves the now-shared callback to tablecmds.c and renames it, per
discussion with Noah Misch.
In the previous coding, callers were faced with an awkward choice:
look up the name, do permissions checks, and then lock the table; or
look up the name, lock the table, and then do permissions checks.
The first choice was wrong because the results of the name lookup
and permissions checks might be out-of-date by the time the table
lock was acquired, while the second allowed a user with no privileges
to interfere with access to a table by users who do have privileges
(e.g. if a malicious backend queues up for an AccessExclusiveLock on
a table on which AccessShareLock is already held, further attempts
to access the table will be blocked until the AccessExclusiveLock
is obtained and the malicious backend's transaction rolls back).
To fix, allow callers of RangeVarGetRelid() to pass a callback which
gets executed after performing the name lookup but before acquiring
the relation lock. If the name lookup is retried (because
invalidation messages are received), the callback will be re-executed
as well, so we get the best of both worlds. RangeVarGetRelid() is
renamed to RangeVarGetRelidExtended(); callers not wishing to supply
a callback can continue to invoke it as RangeVarGetRelid(), which is
now a macro. Since the only one caller that uses nowait = true now
passes a callback anyway, the RangeVarGetRelid() macro defaults nowait
as well. The callback can also be used for supplemental locking - for
example, REINDEX INDEX needs to acquire the table lock before the index
lock to reduce deadlock possibilities.
There's a lot more work to be done here to fix all the cases where this
can be a problem, but this commit provides the general infrastructure
and fixes the following specific cases: REINDEX INDEX, REINDEX TABLE,
LOCK TABLE, and and DROP TABLE/INDEX/SEQUENCE/VIEW/FOREIGN TABLE.
Per discussion with Noah Misch and Alvaro Herrera.
walsender.h should depend on xlog.h, not vice versa. (Actually, the
inclusion was circular until a couple hours ago, which was even sillier;
but Bruce broke it in the expedient rather than logically correct
direction.) Because of that poor decision, plus blind application of
pgrminclude, we had a situation where half the system was depending on
xlog.h to include such unrelated stuff as array.h and guc.h. Clean up
the header inclusion, and manually revert a lot of what pgrminclude had
done so things build again.
This episode reinforces my feeling that pgrminclude should not be run
without adult supervision. Inclusion changes in header files in particular
need to be reviewed with great care. More generally, it'd be good if we
had a clearer notion of module layering to dictate which headers can sanely
include which others ... but that's a big task for another day.
Instead of entering them on transaction startup, we materialize them
only when someone wants to wait, which will occur only during CREATE
INDEX CONCURRENTLY. In Hot Standby mode, the startup process must also
be able to probe for conflicting VXID locks, but the lock need never be
fully materialized, because the startup process does not use the normal
lock wait mechanism. Since most VXID locks never need to touch the
lock manager partition locks, this can significantly reduce blocking
contention on read-heavy workloads.
Patch by me. Review by Jeff Davis.
In the previous coding, we would look up a relation in RangeVarGetRelid,
lock the resulting OID, and then AcceptInvalidationMessages(). While
this was sufficient to ensure that we noticed any changes to the
relation definition before building the relcache entry, it didn't
handle the possibility that the name we looked up no longer referenced
the same OID. This was particularly problematic in the case where a
table had been dropped and recreated: we'd latch on to the entry for
the old relation and fail later on. Now, we acquire the relation lock
inside RangeVarGetRelid, and retry the name lookup if we notice that
invalidation messages have been processed meanwhile. Many operations
that would previously have failed with an error in the presence of
concurrent DDL will now succeed.
There is a good deal of work remaining to be done here: many callers
of RangeVarGetRelid still pass NoLock for one reason or another. In
addition, nothing in this patch guards against the possibility that
the meaning of an unqualified name might change due to the creation
of a relation in a schema earlier in the user's search path than the
one where it was previously found. Furthermore, there's nothing at
all here to guard against similar race conditions for non-relations.
For all that, it's a start.
Noah Misch and Robert Haas
This patch is almost entirely cosmetic --- mostly cleaning up a lot of
neglected comments, and fixing code layout problems in places where the
patch made lines too long and then pgindent did weird things with that.
I did find a bug-of-omission in equalTupleDescs().
There can never be a need to push the indcheckxmin horizon forward, since
any HOT chains that are actually broken with respect to the index must
pre-date its original creation. So we can just avoid changing pg_index
altogether during a REINDEX operation.
This offers a cleaner solution than my previous patch for the problem
found a few days ago that we mustn't try to update pg_index while we are
reindexing it. System catalog indexes will always be created with
indcheckxmin = false during initdb, and with this modified code we should
never try to change their pg_index entries. This avoids special-casing
system catalogs as the former patch did, and should provide a performance
benefit for many cases where REINDEX formerly caused an index to be
considered unusable for a short time.
Back-patch to 8.3 to cover all versions containing HOT. Note that this
patch changes the API for index_build(), but I believe it is unlikely that
any add-on code is calling that directly.
For what seem entirely historical reasons, a bitmask "flags" argument was
recently added to reindex_relation without subsuming its existing boolean
argument into that bitmask. This seems a bit bizarre, so fold them
together.
Ensure that COLLATE at the top level of an index expression is treated the
same as a grammatically separate COLLATE. Fix bogus reverse-parsing logic
in pg_get_indexdef.
pg_newlocale_from_collation does not have enough context to give an error
message that's even a little bit useful, so move the responsibility for
complaining up to its callers. Also, reword ERRCODE_INDETERMINATE_COLLATION
error messages in a less jargony, more message-style-guide-compliant
fashion.
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.
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
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
Failure to do so can lead to constraint violations. This was broken by
commit 1ddc2703a9 on 2010-02-07, so
back-patch to 9.0.
Noah Misch. Regression test by me.
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.
unqualified names.
- Add a missing_ok parameter to get_tablespace_oid.
- Avoid duplicating get_tablespace_od guts in objectNamesToOids.
- Add a missing_ok parameter to get_database_oid.
- Replace get_roleid and get_role_checked with get_role_oid.
- Add get_namespace_oid, get_language_oid, get_am_oid.
- Refactor existing code to use new interfaces.
Thanks to KaiGai Kohei for the review.
before it checks whether the expression is immutable. This covers two cases
that were previously handled poorly:
1. SQL function inlining could reduce the apparent volatility of the
expression, allowing an expression to be accepted where it previously would
not have been. As an example, polymorphic functions must be marked with the
worst-case volatility they have for any argument type, but for specific
argument types they might not be so volatile, so indexing could be allowed.
(Since the planner will refuse to inline functions in cases where the
apparent volatility of the expression would increase, this won't break
any cases that were accepted before.)
2. A nominally immutable function could have default arguments that are
volatile expressions. In such a case insertion of the defaults will increase
both the apparent and actual volatility of the expression, so it is
*necessary* to check this before allowing the expression to be indexed.
Back-patch to 8.4, where default arguments were introduced.
The purpose of this change is to eliminate the need for every caller
of SearchSysCache, SearchSysCacheCopy, SearchSysCacheExists,
GetSysCacheOid, and SearchSysCacheList to know the maximum number
of allowable keys for a syscache entry (currently 4). This will
make it far easier to increase the maximum number of keys in a
future release should we choose to do so, and it makes the code
shorter, too.
Design and review by Tom Lane.
as per my recent proposal.
First, teach IndexBuildHeapScan to not wait for INSERT_IN_PROGRESS or
DELETE_IN_PROGRESS tuples to commit unless the index build is checking
uniqueness/exclusion constraints. If it isn't, there's no harm in just
indexing the in-doubt tuple.
Second, modify VACUUM FULL/CLUSTER to suppress reverifying
uniqueness/exclusion constraint properties while rebuilding indexes of
the target relation. This is reasonable because these commands aren't
meant to deal with corrupted-data situations. Constraint properties
will still be rechecked when an index is rebuilt by a REINDEX command.
This gets us out of the problem that new-style VACUUM FULL would often
wait for other transactions while holding exclusive lock on a system
catalog, leading to probable deadlock because those other transactions
need to look at the catalogs too. Although the real ultimate cause of
the problem is a debatable choice to release locks early after modifying
system catalogs, changing that choice would require pretty serious
analysis and is not something to be undertaken lightly or on a tight
schedule. The present patch fixes the problem in a fairly reasonable
way and should also improve the speed of VACUUM FULL/CLUSTER a little bit.
of shared or nailed system catalogs. This has two key benefits:
* The new CLUSTER-based VACUUM FULL can be applied safely to all catalogs.
* We no longer have to use an unsafe reindex-in-place approach for reindexing
shared catalogs.
CLUSTER on nailed catalogs now works too, although I left it disabled on
shared catalogs because the resulting pg_index.indisclustered update would
only be visible in one database.
Since reindexing shared system catalogs is now fully transactional and
crash-safe, the former special cases in REINDEX behavior have been removed;
shared catalogs are treated the same as non-shared.
This commit does not do anything about the recently-discussed problem of
deadlocks between VACUUM FULL/CLUSTER on a system catalog and other
concurrent queries; will address that in a separate patch. As a stopgap,
parallel_schedule has been tweaked to run vacuum.sql by itself, to avoid
such failures during the regression tests.
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"
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
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
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.
when we are waiting for old snapshots to go away during a concurrent index
build. In particular, this rule lets us avoid waiting for
idle-in-transaction sessions.
This logic could be improved further if we had some way to wake up when
the session we are currently waiting for goes idle-in-transaction. However
that would be a significantly more complex/invasive patch, so it'll have to
wait for some other day.
Simon Riggs, with some improvements by Tom.
temp relations; this is no more expensive than before, now that we have
pg_class.relistemp. Insert tests into bufmgr.c to prevent attempting
to fetch pages from nonlocal temp relations. This provides a low-level
defense against bugs-of-omission allowing temp pages to be loaded into shared
buffers, as in the contrib/pgstattuple problem reported by Stuart Bishop.
While at it, tweak a bunch of places to use new relcache tests (instead of
expensive probes into pg_namespace) to detect local or nonlocal temp tables.
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.
Tom Lane
Robert Haas
Bruce Momjian
Peter Eisentraut
Magnus Hagander
Simon Riggs
Alvaro Herrera