In a top-level CALL, the values of INOUT arguments will be returned as a
result row. In PL/pgSQL, the values are assigned back to the input
arguments. In other languages, the same convention as for return a
record from a function is used. That does not require any code changes
in the PL implementations.
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
The new column distinguishes normal functions, procedures, aggregates,
and window functions. This replaces the existing columns proisagg and
proiswindow, and replaces the convention that procedures are indicated
by prorettype == 0. Also change prorettype to be VOIDOID for procedures.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
If a plpgsql function is declared to return a domain type, and the domain's
constraints forbid a null value, it was nonetheless possible to return
NULL, because we didn't bother to check the constraints for a null result.
I'd noticed this while fooling with domains-over-composite, but had not
gotten around to fixing it immediately.
Add a regression test script exercising this and various other domain
cases, largely borrowed from the plpython_types test.
Although this is clearly a bug fix, I'm not sure whether anyone would
thank us for changing the behavior in stable branches, so I'm inclined
not to back-patch.
These features were never implemented previously for composite or record
variables ... not that the documentation admitted it, so there's no doc
updates here.
This also fixes some issues concerning enforcing DOMAIN NOT NULL
constraints against plpgsql variables, although I'm not sure that
that topic is completely dealt with.
I created a new plpgsql test file for these features, and moved the
one relevant existing test case into that file.
Tom Lane, reviewed by Daniel Gustafsson
Discussion: https://postgr.es/m/18362.1514605650@sss.pgh.pa.us
Over the years we've accreted quite a few special variables that are
predefined in plpgsql trigger functions. The cost of initializing these
variables to their defined values turns out to be a significant part of
the runtime of simple triggers; but, undoubtedly, most real-world triggers
never examine the values of most of these variables.
To improve matters, invent the notion of a variable that has a "promise"
attached to it, specifying which of the predetermined values should be
assigned to the variable if anything ever reads it. This eliminates all
the unneeded startup overhead, in return for a small penalty on accesses
to these variables.
Tom Lane, reviewed by Pavel Stehule
Discussion: https://postgr.es/m/11986.1514407114@sss.pgh.pa.us
Previously, copy_plpgsql_datum did a separate palloc for each variable
needing instance-local storage. In simple benchmarks this made for a
noticeable fraction of the total runtime. Improve it by precalculating
the space needed for all of a function's variables and doing just one
palloc for all of them.
In passing, remove PLPGSQL_DTYPE_EXPR from the list of plpgsql "datum"
types, since in fact it has nothing in common with the others, and there
is noplace that needs to discriminate on the basis of dtype between an
expression and any type of datum. And add comments clarifying which
datum struct fields are generic and which aren't.
Tom Lane, reviewed by Pavel Stehule
Discussion: https://postgr.es/m/11986.1514407114@sss.pgh.pa.us
Formerly, DTYPE_REC was used only for variables declared as "record";
variables of named composite types used DTYPE_ROW, which is faster for
some purposes but much less flexible. In particular, the ROW code paths
are entirely incapable of dealing with DDL-caused changes to the number
or data types of the columns of a row variable, once a particular plpgsql
function has been parsed for the first time in a session. And, since the
stored representation of a ROW isn't a tuple, there wasn't any easy way
to deal with variables of domain-over-composite types, since the domain
constraint checking code would expect the value to be checked to be a
tuple. A lesser, but still real, annoyance is that ROW format cannot
represent a true NULL composite value, only a row of per-field NULL
values, which is not exactly the same thing.
Hence, switch to using DTYPE_REC for all composite-typed variables,
whether "record", named composite type, or domain over named composite
type. DTYPE_ROW remains but is used only for its native purpose, to
represent a fixed-at-compile-time list of variables, for instance the
targets of an INTO clause.
To accomplish this without taking significant performance losses, introduce
infrastructure that allows storing composite-type variables as "expanded
objects", similar to the "expanded array" infrastructure introduced in
commit 1dc5ebc90. A composite variable's value is thereby kept (most of
the time) in the form of separate Datums, so that field accesses and
updates are not much more expensive than they were in the ROW format.
This holds the line, more or less, on performance of variables of named
composite types in field-access-intensive microbenchmarks, and makes
variables declared "record" perform much better than before in similar
tests. In addition, the logic involved with enforcing composite-domain
constraints against updates of individual fields is in the expanded
record infrastructure not plpgsql proper, so that it might be reusable
for other purposes.
In further support of this, introduce a typcache feature for assigning a
unique-within-process identifier to each distinct tuple descriptor of
interest; in particular, DDL alterations on composite types result in a new
identifier for that type. This allows very cheap detection of the need to
refresh tupdesc-dependent data. This improves on the "tupDescSeqNo" idea
I had in commit 687f096ea: that assigned identifying sequence numbers to
successive versions of individual composite types, but the numbers were not
unique across different types, nor was there support for assigning numbers
to registered record types.
In passing, allow plpgsql functions to accept as well as return type
"record". There was no good reason for the old restriction, and it
was out of step with most of the other PLs.
Tom Lane, reviewed by Pavel Stehule
Discussion: https://postgr.es/m/8962.1514399547@sss.pgh.pa.us
In each of the supplied procedural languages (PL/pgSQL, PL/Perl,
PL/Python, PL/Tcl), add language-specific commit and rollback
functions/commands to control transactions in procedures in that
language. Add similar underlying functions to SPI. Some additional
cleanup so that transaction commit or abort doesn't blow away data
structures still used by the procedure call. Add execution context
tracking to CALL and DO statements so that transaction control commands
can only be issued in top-level procedure and block calls, not function
calls or other procedure or block calls.
- SPI
Add a new function SPI_connect_ext() that is like SPI_connect() but
allows passing option flags. The only option flag right now is
SPI_OPT_NONATOMIC. A nonatomic SPI connection can execute transaction
control commands, otherwise it's not allowed. This is meant to be
passed down from CALL and DO statements which themselves know in which
context they are called. A nonatomic SPI connection uses different
memory management. A normal SPI connection allocates its memory in
TopTransactionContext. For nonatomic connections we use PortalContext
instead. As the comment in SPI_connect_ext() (previously SPI_connect())
indicates, one could potentially use PortalContext in all cases, but it
seems safest to leave the existing uses alone, because this stuff is
complicated enough already.
SPI also gets new functions SPI_start_transaction(), SPI_commit(), and
SPI_rollback(), which can be used by PLs to implement their transaction
control logic.
- portalmem.c
Some adjustments were made in the code that cleans up portals at
transaction abort. The portal code could already handle a command
*committing* a transaction and continuing (e.g., VACUUM), but it was not
quite prepared for a command *aborting* a transaction and continuing.
In AtAbort_Portals(), remove the code that marks an active portal as
failed. As the comment there already predicted, this doesn't work if
the running command wants to keep running after transaction abort. And
it's actually not necessary, because pquery.c is careful to run all
portal code in a PG_TRY block and explicitly runs MarkPortalFailed() if
there is an exception. So the code in AtAbort_Portals() is never used
anyway.
In AtAbort_Portals() and AtCleanup_Portals(), we need to be careful not
to clean up active portals too much. This mirrors similar code in
PreCommit_Portals().
- PL/Perl
Gets new functions spi_commit() and spi_rollback()
- PL/pgSQL
Gets new commands COMMIT and ROLLBACK.
Update the PL/SQL porting example in the documentation to reflect that
transactions are now possible in procedures.
- PL/Python
Gets new functions plpy.commit and plpy.rollback.
- PL/Tcl
Gets new commands commit and rollback.
Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
PL/pgSQL "pins" internally generated (unnamed) portals so that user code
cannot close them by guessing their names. This logic is also useful in
other languages and really for any code. So move that logic into SPI.
An unnamed portal obtained through SPI_cursor_open() and related
functions is now automatically pinned, and SPI_cursor_close()
automatically unpins a portal that is pinned.
In the core distribution, this affects PL/Perl and PL/Python, preventing
users from manually closing cursors created by spi_query and
plpy.cursor, respectively. (PL/Tcl does not currently offer any cursor
functionality.)
Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
plpgsql's five different loop control statements contained three distinct
implementations of the same (or what ought to be the same, at least)
logic for handling return/exit/continue result codes from their child
statements. At best, that's trouble waiting to happen, and there seems
no very good reason for the coding to be so different. Refactor so that
all the common logic is expressed in a single macro.
Discussion: https://postgr.es/m/26314.1514670401@sss.pgh.pa.us
This patch does three interrelated things:
* Create a new expression execution step type EEOP_PARAM_CALLBACK
and add the infrastructure needed for add-on modules to generate that.
As discussed, the best control mechanism for that seems to be to add
another hook function to ParamListInfo, which will be called by
ExecInitExpr if it's supplied and a PARAM_EXTERN Param is found.
For stand-alone expressions, we add a new entry point to allow the
ParamListInfo to be specified directly, since it can't be retrieved
from the parent plan node's EState.
* Redesign the API for the ParamListInfo paramFetch hook so that the
ParamExternData array can be entirely virtual. This also lets us get rid
of ParamListInfo.paramMask, instead leaving it to the paramFetch hook to
decide which param IDs should be accessible or not. plpgsql_param_fetch
was already doing the identical masking check, so having callers do it too
seemed redundant. While I was at it, I added a "speculative" flag to
paramFetch that the planner can specify as TRUE to avoid unwanted failures.
This solves an ancient problem for plpgsql that it couldn't provide values
of non-DTYPE_VAR variables to the planner for fear of triggering premature
"record not assigned yet" or "field not found" errors during planning.
* Rework plpgsql to get rid of the need for "unshared" parameter lists,
by dint of turning the single ParamListInfo per estate into a nearly
read-only data structure that doesn't instantiate any per-variable data.
Instead, the paramFetch hook controls access to per-variable data and can
make the right decisions on the fly, replacing the cases that we used to
need multiple ParamListInfos for. This might perhaps have been a
performance loss on its own, but by using a paramCompile hook we can
bypass plpgsql_param_fetch entirely during normal query execution.
(It's now only called when, eg, we copy the ParamListInfo into a cursor
portal. copyParamList() or SerializeParamList() effectively instantiate
the virtual parameter array as a simple physical array without a
paramFetch hook, which is what we want in those cases.) This allows
reverting most of commit 6c82d8d1f, though I kept the cosmetic
code-consolidation aspects of that (eg the assign_simple_var function).
Performance testing shows this to be at worst a break-even change,
and it can provide wins ranging up to 20% in test cases involving
accesses to fields of "record" variables. The fact that values of
such variables can now be exposed to the planner might produce wins
in some situations, too, but I've not pursued that angle.
In passing, remove the "parent" pointer from the arguments to
ExecInitExprRec and related functions, instead storing that pointer in a
transient field in ExprState. The ParamListInfo pointer for a stand-alone
expression is handled the same way; we'd otherwise have had to add
yet another recursively-passed-down argument in expression compilation.
Discussion: https://postgr.es/m/32589.1513706441@sss.pgh.pa.us
If one exits and re-enters a DECLARE ... BEGIN ... END block within a
single execution of a plpgsql function, perhaps due to a surrounding loop,
the declared variables are supposed to get re-initialized to null (or
whatever their initializer is). But this failed to happen for variables
of type "record", because while exec_stmt_block() expected such variables
to be included in the block's initvarnos list, plpgsql_add_initdatums()
only adds DTYPE_VAR variables to that list. This bug appears to have
been there since the aboriginal addition of plpgsql to our tree.
Fix by teaching plpgsql_add_initdatums() to include DTYPE_REC variables
as well. (We don't need to consider other DTYPEs because they don't
represent separately-stored values.) I failed to resist the temptation
to make some nearby cosmetic adjustments, too.
No back-patch, because there have not been field complaints, and it
seems possible that somewhere out there someone has code depending
on the incorrect behavior. In any case this change would have no
impact on correctly-written code.
Discussion: https://postgr.es/m/22994.1512800671@sss.pgh.pa.us
plpgsql's function exec_move_row() handles assignment of a composite
source value to either a PLpgSQL_rec or PLpgSQL_row target variable.
Oddly, rather than taking a single target argument which it could do
run-time type detection on, it was coded to take two separate arguments
(only one of which is allowed to be non-NULL). This choice had then
back-propagated into storing two separate target variables in various
plpgsql statement nodes, with lots of duplicative coding and awkward
interface logic to support that. Simplify matters by folding those
pairs down to single variables, distinguishing the two cases only
where we must ... which turns out to be only in exec_move_row itself.
This is purely refactoring and should not change any behavior.
In passing, remove unused field PLpgSQL_stmt_open.returntype.
Discussion: https://postgr.es/m/11787.1512713374@sss.pgh.pa.us
This adds a new object type "procedure" that is similar to a function
but does not have a return type and is invoked by the new CALL statement
instead of SELECT or similar. This implementation is aligned with the
SQL standard and compatible with or similar to other SQL implementations.
This commit adds new commands CALL, CREATE/ALTER/DROP PROCEDURE, as well
as ALTER/DROP ROUTINE that can refer to either a function or a
procedure (or an aggregate function, as an extension to SQL). There is
also support for procedures in various utility commands such as COMMENT
and GRANT, as well as support in pg_dump and psql. Support for defining
procedures is available in all the languages supplied by the core
distribution.
While this commit is mainly syntax sugar around existing functionality,
future features will rely on having procedures as a separate object
type.
Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
The lower case spellings are C and C++ standard and are used in most
parts of the PostgreSQL sources. The upper case spellings are only used
in some files/modules. So standardize on the standard spellings.
The APIs for ICU, Perl, and Windows define their own TRUE and FALSE, so
those are left as is when using those APIs.
In code comments, we use the lower-case spelling for the C concepts and
keep the upper-case spelling for the SQL concepts.
Reviewed-by: Michael Paquier <michael.paquier@gmail.com>
This was always intended to work, but due to an oversight in
max_parallel_hazard_walker, it didn't. In testing, we missed the
fact that it was only working for custom plans, where the parameter
value has been substituted for the parameter itself early enough
that everything worked. In a generic plan, the Param node survives
and must be treated as parallel-safe. SerializeParamList provides
for the transmission of parameter values to workers.
Amit Kapila with help from Kuntal Ghosh. Some changes by me.
Discussion: http://postgr.es/m/CAA4eK1+_BuZrmVCeua5Eqnm4Co9DAXdM5HPAOE2J19ePbR912Q@mail.gmail.com
This is a mechanical change in preparation for a later commit that
will change the layout of TupleDesc. Introducing a macro to abstract
the details of where attributes are stored will allow us to change
that in separate step and revise it in future.
Author: Thomas Munro, editorialized by Andres Freund
Reviewed-By: Andres Freund
Discussion: https://postgr.es/m/CAEepm=0ZtQ-SpsgCyzzYpsXS6e=kZWqk3g5Ygn3MDV7A8dabUA@mail.gmail.com
Commit 00418c612 expected that the plan generated for a simple-expression
query would always be a plain Result node. However, if force_parallel_mode
is on, the planner might stick a Gather atop that. Cope by looking through
the Gather. For safety, assert that the Gather's tlist is trivial.
Per buildfarm.
Discussion: https://postgr.es/m/23425.1502822098@sss.pgh.pa.us
plpgsql wants to recognize expressions that it can execute directly
via ExecEvalExpr() instead of going through the full SPI machinery.
Originally the test for this consisted of recursively groveling through
the post-planning expression tree to see if it contained only nodes that
plpgsql recognized as safe. That was a major maintenance headache, since
it required updating plpgsql every time we added any kind of expression
node. It was also kind of expensive, so over time we added various
pre-planning checks to try to short-circuit having to do that.
Robert Haas pointed out that as of the SRF-processing changes in v10,
particularly the addition of Query.hasTargetSRFs, there really isn't
any reason to make the recursive scan at all: the initial checks cover
everything we really care about. We do have to make sure that those
checks agree with what inline_function() considers, so that inlining
of a function that formerly wasn't inlined can't cause an expression
considered simple to become non-simple.
Hence, delete the recursive function exec_simple_check_node(), and tweak
those other tests to more exactly agree with inline_function(). Adjust
some comments and function naming to match.
Discussion: https://postgr.es/m/CA+TgmoZGZpwdEV2FQWaVxA_qZXsQE1DAS5Fu8fwxXDNvfndiUQ@mail.gmail.com
Don't move parenthesized lines to the left, even if that means they
flow past the right margin.
By default, BSD indent lines up statement continuation lines that are
within parentheses so that they start just to the right of the preceding
left parenthesis. However, traditionally, if that resulted in the
continuation line extending to the right of the desired right margin,
then indent would push it left just far enough to not overrun the margin,
if it could do so without making the continuation line start to the left of
the current statement indent. That makes for a weird mix of indentations
unless one has been completely rigid about never violating the 80-column
limit.
This behavior has been pretty universally panned by Postgres developers.
Hence, disable it with indent's new -lpl switch, so that parenthesized
lines are always lined up with the preceding left paren.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
Change pg_bsd_indent to follow upstream rules for placement of comments
to the right of code, and remove pgindent hack that caused comments
following #endif to not obey the general rule.
Commit e3860ffa4d wasn't actually using
the published version of pg_bsd_indent, but a hacked-up version that
tried to minimize the amount of movement of comments to the right of
code. The situation of interest is where such a comment has to be
moved to the right of its default placement at column 33 because there's
code there. BSD indent has always moved right in units of tab stops
in such cases --- but in the previous incarnation, indent was working
in 8-space tab stops, while now it knows we use 4-space tabs. So the
net result is that in about half the cases, such comments are placed
one tab stop left of before. This is better all around: it leaves
more room on the line for comment text, and it means that in such
cases the comment uniformly starts at the next 4-space tab stop after
the code, rather than sometimes one and sometimes two tabs after.
Also, ensure that comments following #endif are indented the same
as comments following other preprocessor commands such as #else.
That inconsistency turns out to have been self-inflicted damage
from a poorly-thought-through post-indent "fixup" in pgindent.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
The new indent version includes numerous fixes thanks to Piotr Stefaniak.
The main changes visible in this commit are:
* Nicer formatting of function-pointer declarations.
* No longer unexpectedly removes spaces in expressions using casts,
sizeof, or offsetof.
* No longer wants to add a space in "struct structname *varname", as
well as some similar cases for const- or volatile-qualified pointers.
* Declarations using PG_USED_FOR_ASSERTS_ONLY are formatted more nicely.
* Fixes bug where comments following declarations were sometimes placed
with no space separating them from the code.
* Fixes some odd decisions for comments following case labels.
* Fixes some cases where comments following code were indented to less
than the expected column 33.
On the less good side, it now tends to put more whitespace around typedef
names that are not listed in typedefs.list. This might encourage us to
put more effort into typedef name collection; it's not really a bug in
indent itself.
There are more changes coming after this round, having to do with comment
indentation and alignment of lines appearing within parentheses. I wanted
to limit the size of the diffs to something that could be reviewed without
one's eyes completely glazing over, so it seemed better to split up the
changes as much as practical.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
This extends the castNode() notation introduced by commit 5bcab1114 to
provide, in one step, extraction of a list cell's pointer and coercion to
a concrete node type. For example, "lfirst_node(Foo, lc)" is the same
as "castNode(Foo, lfirst(lc))". Almost half of the uses of castNode
that have appeared so far include a list extraction call, so this is
pretty widely useful, and it saves a few more keystrokes compared to the
old way.
As with the previous patch, back-patch the addition of these macros to
pg_list.h, so that the notation will be available when back-patching.
Patch by me, after an idea of Andrew Gierth's.
Discussion: https://postgr.es/m/14197.1491841216@sss.pgh.pa.us
Commit 59702716 added transition table support to PL/pgsql so that
SQL queries in trigger functions could access those transient
tables. In order to provide the same level of support for PL/perl,
PL/python and PL/tcl, refactor the relevant code into a new
function SPI_register_trigger_data. Call the new function in the
trigger handler of all four PLs, and document it as a public SPI
function so that authors of out-of-tree PLs can do the same.
Also get rid of a second QueryEnvironment object that was
maintained by PL/pgsql. That was previously used to deal with
cursors, but the same approach wasn't appropriate for PLs that are
less tangled up with core code. Instead, have SPI_cursor_open
install the connection's current QueryEnvironment, as already
happens for SPI_execute_plan.
While in the docs, remove the note that transition tables were only
supported in C and PL/pgSQL triggers, and correct some ommissions.
Thomas Munro with some work by Kevin Grittner (mostly docs)
This replaces the old, recursive tree-walk based evaluation, with
non-recursive, opcode dispatch based, expression evaluation.
Projection is now implemented as part of expression evaluation.
This both leads to significant performance improvements, and makes
future just-in-time compilation of expressions easier.
The speed gains primarily come from:
- non-recursive implementation reduces stack usage / overhead
- simple sub-expressions are implemented with a single jump, without
function calls
- sharing some state between different sub-expressions
- reduced amount of indirect/hard to predict memory accesses by laying
out operation metadata sequentially; including the avoidance of
nearly all of the previously used linked lists
- more code has been moved to expression initialization, avoiding
constant re-checks at evaluation time
Future just-in-time compilation (JIT) has become easier, as
demonstrated by released patches intended to be merged in a later
release, for primarily two reasons: Firstly, due to a stricter split
between expression initialization and evaluation, less code has to be
handled by the JIT. Secondly, due to the non-recursive nature of the
generated "instructions", less performance-critical code-paths can
easily be shared between interpreted and compiled evaluation.
The new framework allows for significant future optimizations. E.g.:
- basic infrastructure for to later reduce the per executor-startup
overhead of expression evaluation, by caching state in prepared
statements. That'd be helpful in OLTPish scenarios where
initialization overhead is measurable.
- optimizing the generated "code". A number of proposals for potential
work has already been made.
- optimizing the interpreter. Similarly a number of proposals have
been made here too.
The move of logic into the expression initialization step leads to some
backward-incompatible changes:
- Function permission checks are now done during expression
initialization, whereas previously they were done during
execution. In edge cases this can lead to errors being raised that
previously wouldn't have been, e.g. a NULL array being coerced to a
different array type previously didn't perform checks.
- The set of domain constraints to be checked, is now evaluated once
during expression initialization, previously it was re-built
every time a domain check was evaluated. For normal queries this
doesn't change much, but e.g. for plpgsql functions, which caches
ExprStates, the old set could stick around longer. The behavior
around might still change.
Author: Andres Freund, with significant changes by Tom Lane,
changes by Heikki Linnakangas
Reviewed-By: Tom Lane, Heikki Linnakangas
Discussion: https://postgr.es/m/20161206034955.bh33paeralxbtluv@alap3.anarazel.de
In SQL, the ability to use parallel query was previous contingent on
fcache->readonly_func, which is only set for non-volatile functions;
but the volatility of a function has no bearing on whether queries
inside it can use parallelism. Remove that condition.
SPI_execute and SPI_execute_with_args always run the plan just once,
though not necessarily to completion. Given the changes in commit
691b8d5928, it's sensible to pass
CURSOR_OPT_PARALLEL_OK here, so do that. This improves access to
parallelism for any caller that uses these functions to execute
queries. Such callers include plperl, plpython, pltcl, and plpgsql,
though it's not the case that they all use these functions
exclusively.
In plpgsql, allow parallel query for plain SELECT queries (as
opposed to PERFORM, which already worked) and for plain expressions
(which probably won't go through the executor at all, because they
will likely be simple expressions, but if they do then this helps).
Rafia Sabih and Robert Haas, reviewed by Dilip Kumar and Amit Kapila
Discussion: http://postgr.es/m/CAOGQiiMfJ+4SQwgG=6CVHWoisiU0+7jtXSuiyXBM3y=A=eJzmg@mail.gmail.com
Commit 7aea8e4f2d allowed a parallel
plan to be generated when for a RETURN QUERY or RETURN QUERY EXECUTE
statement in a PL/pgsql block, but that's a bad idea because plplgsql
asks the executor for 50 rows at a time. That means that we'll always
be running serially a plan that was intended for parallel execution,
which is not a good idea. Fix by not requesting a parallel plan from
the outset.
Per discussion, back-patch to 9.6. There is a slight risk that, due
to optimizer error, somebody could have a case where the parallel plan
executed serially is actually faster than the supposedly-best serial
plan, but the consensus seems to be that that's not sufficient
justification for leaving 9.6 unpatched.
Discussion: http://postgr.es/m/CA+TgmoZ_ZuH+auEeeWnmtorPsgc_SmP+XWbDsJ+cWvWBSjNwDQ@mail.gmail.com
Discussion: http://postgr.es/m/CA+TgmobXEhvHbJtWDuPZM9bVSLiTj-kShxQJ2uM5GPDze9fRYA@mail.gmail.com
We have a project policy that every .c file should start by including
postgres.h, postgres_fe.h, or c.h as appropriate; and then there is no
need for any .h file to explicitly include any of these. (The core
reason for this policy is to make it easy to verify that pg_config_os.h
is included before any system headers such as <stdio.h>; without that,
we have portability issues on some platforms due to variation in largefile
options across different modules in the backend. Also, if .h files were
responsible for choosing which of these key headers to include, .h files
that need to be includable in either frontend or backend compiles would be
in trouble.)
plpgsql was blithely ignoring this policy, so whack it upside the head
until it complies. I also chose to standardize on including plpgsql's
own .h files after all core-system headers that it pulls in. That
could've been done either way, but this way seems saner.
Discussion: https://postgr.es/m/CAEepm=2zCoeq3QxVwhS5DFeUh=yU6z81pbWMgfOB8OzyiBwxzw@mail.gmail.com
Discussion: https://postgr.es/m/11634.1488932128@sss.pgh.pa.us
When I wrote commit ab1f0c822, I really missed the castNode() macro that
Peter E. had proposed shortly before. This back-fills the uses I would
have put it to. It's probably not all that significant, but there are
more assertions here than there were before, and conceivably they will
help catch any bugs associated with those representation changes.
I left behind a number of usages like "(Query *) copyObject(query_var)".
Those could have been converted as well, but Peter has proposed another
notational improvement that would handle copyObject cases automatically,
so I let that be for now.
Since 69f4b9c plain expression evaluation (and thus normal projection)
can't return sets of tuples anymore. Thus remove code dealing with
that possibility.
This will require adjustments in external code using
ExecEvalExpr()/ExecProject() - that should neither be hard nor very
common.
Author: Andres Freund and Tom Lane
Discussion: https://postgr.es/m/20160822214023.aaxz5l4igypowyri@alap3.anarazel.de
This patch makes several changes that improve the consistency of
representation of lists of statements. It's always been the case
that the output of parse analysis is a list of Query nodes, whatever
the types of the individual statements in the list. This patch brings
similar consistency to the outputs of raw parsing and planning steps:
* The output of raw parsing is now always a list of RawStmt nodes;
the statement-type-dependent nodes are one level down from that.
* The output of pg_plan_queries() is now always a list of PlannedStmt
nodes, even for utility statements. In the case of a utility statement,
"planning" just consists of wrapping a CMD_UTILITY PlannedStmt around
the utility node. This list representation is now used in Portal and
CachedPlan plan lists, replacing the former convention of intermixing
PlannedStmts with bare utility-statement nodes.
Now, every list of statements has a consistent head-node type depending
on how far along it is in processing. This allows changing many places
that formerly used generic "Node *" pointers to use a more specific
pointer type, thus reducing the number of IsA() tests and casts needed,
as well as improving code clarity.
Also, the post-parse-analysis representation of DECLARE CURSOR is changed
so that it looks more like EXPLAIN, PREPARE, etc. That is, the contained
SELECT remains a child of the DeclareCursorStmt rather than getting flipped
around to be the other way. It's now true for both Query and PlannedStmt
that utilityStmt is non-null if and only if commandType is CMD_UTILITY.
That allows simplifying a lot of places that were testing both fields.
(I think some of those were just defensive programming, but in many places,
it was actually necessary to avoid confusing DECLARE CURSOR with SELECT.)
Because PlannedStmt carries a canSetTag field, we're also able to get rid
of some ad-hoc rules about how to reconstruct canSetTag for a bare utility
statement; specifically, the assumption that a utility is canSetTag if and
only if it's the only one in its list. While I see no near-term need for
relaxing that restriction, it's nice to get rid of the ad-hocery.
The API of ProcessUtility() is changed so that what it's passed is the
wrapper PlannedStmt not just the bare utility statement. This will affect
all users of ProcessUtility_hook, but the changes are pretty trivial; see
the affected contrib modules for examples of the minimum change needed.
(Most compilers should give pointer-type-mismatch warnings for uncorrected
code.)
There's also a change in the API of ExplainOneQuery_hook, to pass through
cursorOptions instead of expecting hook functions to know what to pick.
This is needed because of the DECLARE CURSOR changes, but really should
have been done in 9.6; it's unlikely that any extant hook functions
know about using CURSOR_OPT_PARALLEL_OK.
Finally, teach gram.y to save statement boundary locations in RawStmt
nodes, and pass those through to Query and PlannedStmt nodes. This allows
more intelligent handling of cases where a source query string contains
multiple statements. This patch doesn't actually do anything with the
information, but a follow-on patch will. (Passing this information through
cleanly is the true motivation for these changes; while I think this is all
good cleanup, it's unlikely we'd have bothered without this end goal.)
catversion bump because addition of location fields to struct Query
affects stored rules.
This patch is by me, but it owes a good deal to Fabien Coelho who did
a lot of preliminary work on the problem, and also reviewed the patch.
Discussion: https://postgr.es/m/alpine.DEB.2.20.1612200926310.29821@lancre
The idea behind SPI_push was to allow transitioning back into an
"unconnected" state when a SPI-using procedure calls unrelated code that
might or might not invoke SPI. That sounds good, but in practice the only
thing it does for us is to catch cases where a called SPI-using function
forgets to call SPI_connect --- which is a highly improbable failure mode,
since it would be exposed immediately by direct testing of said function.
As against that, we've had multiple bugs induced by forgetting to call
SPI_push/SPI_pop around code that might invoke SPI-using functions; these
are much harder to catch and indeed have gone undetected for years in some
cases. And we've had to band-aid around some problems of this ilk by
introducing conditional push/pop pairs in some places, which really kind
of defeats the purpose altogether; if we can't draw bright lines between
connected and unconnected code, what's the point?
Hence, get rid of SPI_push[_conditional], SPI_pop[_conditional], and the
underlying state variable _SPI_curid. It turns out SPI_restore_connection
can go away too, which is a nice side benefit since it was never more than
a kluge. Provide no-op macros for the deleted functions so as to avoid an
API break for external modules.
A side effect of this removal is that SPI_palloc and allied functions no
longer permit being called when unconnected; they'll throw an error
instead. The apparent usefulness of the previous behavior was a mirage
as well, because it was depended on by only a few places (which I fixed in
preceding commits), and it posed a risk of allocations being unexpectedly
long-lived if someone forgot a SPI_push call.
Discussion: <20808.1478481403@sss.pgh.pa.us>
Invent a new function heap_modify_tuple_by_cols() that is functionally
equivalent to SPI_modifytuple except that it always allocates its result
by simple palloc. I chose however to make the API details a bit more
like heap_modify_tuple: pass a tupdesc rather than a Relation, and use
bool convention for the isnull array.
Use this function in place of SPI_modifytuple at all call sites where the
intended behavior is to allocate in current context. (There actually are
only two call sites left that depend on the old behavior, which makes me
wonder if we should just drop this function rather than keep it.)
This new function is easier to use than heap_modify_tuple() for purposes
of replacing a single column (or, really, any fixed number of columns).
There are a number of places where it would simplify the code to change
over, but I resisted that temptation for the moment ... everywhere except
in plpgsql's exec_assign_value(); changing that might offer some small
performance benefit, so I did it.
This is on the way to removing SPI_push/SPI_pop, but it seems like
good code cleanup in its own right.
Discussion: <9633.1478552022@sss.pgh.pa.us>
We must do this in case the expression evaluation results in calling
another plpgsql function (or, really, anything using SPI). I missed
the need for this when I converted exec_cast_value() from doing a
simple InputFunctionCall() to doing ExecEvalExpr() in commit 1345cc67b.
There is a SPI_push_conditional in InputFunctionCall(), so that there
was no bug before that.
Per bug #14414 from Marcos Castedo. Add a regression test based on his
example, which was that a plpgsql function in a domain check constraint
didn't work when assigning to a domain-type variable within plpgsql.
Report: <20161106010947.1387.66380@wrigleys.postgresql.org>
Teach the parser to reject misplaced set-returning functions during parse
analysis using p_expr_kind, in much the same way as we do for aggregates
and window functions (cf commit eaccfded9). While this isn't complete
(it misses nesting-based restrictions), it's much better than the previous
error reporting for such cases, and it allows elimination of assorted
ad-hoc expression_returns_set() error checks. We could add nesting checks
later if it seems important to catch all cases at parse time.
There is one case the parser will now throw error for although previous
versions allowed it, which is SRFs in the tlist of an UPDATE. That never
behaved sensibly (since it's ill-defined which generated row should be
used to perform the update) and it's hard to see why it should not be
treated as an error. It's a release-note-worthy change though.
Also, add a new Query field hasTargetSRFs reporting whether there are
any SRFs in the targetlist (including GROUP BY/ORDER BY expressions).
The parser can now set that basically for free during parse analysis,
and we can use it in a number of places to avoid expression_returns_set
searches. (There will be more such checks soon.) In some places, this
allows decontorting the logic since it's no longer expensive to check for
SRFs in the tlist --- so I made the checks parallel to the handling of
hasAggs/hasWindowFuncs wherever it seemed appropriate.
catversion bump because adding a Query field changes stored rules.
Andres Freund and Tom Lane
Discussion: <24639.1473782855@sss.pgh.pa.us>
plpgsql.h defines a number of enums, but most of the code passes them
around as ints. Update structs and function prototypes to take enum
types instead. This clarifies the struct definitions in plpgsql.h in
particular.
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
I found that half a dozen (nearly 5%) of our AllocSetContextCreate calls
had typos in the context-sizing parameters. While none of these led to
especially significant problems, they did create minor inefficiencies,
and it's now clear that expecting people to copy-and-paste those calls
accurately is not a great idea. Let's reduce the risk of future errors
by introducing single macros that encapsulate the common use-cases.
Three such macros are enough to cover all but two special-purpose contexts;
those two calls can be left as-is, I think.
While this patch doesn't in itself improve matters for third-party
extensions, it doesn't break anything for them either, and they can
gradually adopt the simplified notation over time.
In passing, change TopMemoryContext to use the default allocation
parameters. Formerly it could only be extended 8K at a time. That was
probably reasonable when this code was written; but nowadays we create
many more contexts than we did then, so that it's not unusual to have a
couple hundred K in TopMemoryContext, even without considering various
dubious code that sticks other things there. There seems no good reason
not to let it use growing blocks like most other contexts.
Back-patch to 9.6, mostly because that's still close enough to HEAD that
it's easy to do so, and keeping the branches in sync can be expected to
avoid some future back-patching pain. The bugs fixed by these changes
don't seem to be significant enough to justify fixing them further back.
Discussion: <21072.1472321324@sss.pgh.pa.us>
In some cases, exiting out of a plpgsql statement due to an error, then
catching the error in a surrounding exception block, led to leakage of
temporary data the statement was working with, because we kept all such
data in the function-lifespan SPI Proc context. Iterating such behavior
many times within one function call thus led to noticeable memory bloat.
To fix, create an additional memory context meant to have statement
lifespan. Since many plpgsql statements, particularly the simpler/more
common ones, don't need this, create it only on demand. Reset this context
at the end of any statement that uses it, and arrange for exception cleanup
to reset it too, thereby fixing the memory-leak issue. Allow a stack of
such contexts to exist to handle cases where a compound statement needs
statement-lifespan data that persists across calls of inner statements.
While at it, clean up code and improve comments referring to the existing
short-term memory context, which by plpgsql convention is the per-tuple
context of the eval_econtext ExprContext. We now uniformly refer to that
as the eval_mcontext, whereas the new statement-lifespan memory contexts
are called stmt_mcontext.
This change adds some context-creation overhead, but on the other hand
it allows removal of some retail pfree's in favor of context resets.
On balance it seems to be about a wash performance-wise.
In principle this is a bug fix, but it seems too invasive for a back-patch,
and the infrequency of complaints weighs against taking the risk in the
back branches. So we'll fix it only in HEAD, at least for now.
Tom Lane, reviewed by Pavel Stehule
Discussion: <17863.1469142152@sss.pgh.pa.us>
We implement a dozen or so parameterless functions that the SQL standard
defines special syntax for. Up to now, that was done by converting them
into more or less ad-hoc constructs such as "'now'::text::date". That's
messy for multiple reasons: it exposes what should be implementation
details to users, and performance is worse than it needs to be in several
cases. To improve matters, invent a new expression node type
SQLValueFunction that can represent any of these parameterless functions.
Bump catversion because this changes stored parsetrees for rules.
Discussion: <30058.1463091294@sss.pgh.pa.us>
This patch widens SPI_processed, EState's es_processed field, PortalData's
portalPos field, FuncCallContext's call_cntr and max_calls fields,
ExecutorRun's count argument, PortalRunFetch's result, and the max number
of rows in a SPITupleTable to uint64, and deals with (I hope) all the
ensuing fallout. Some of these values were declared uint32 before, and
others "long".
I also removed PortalData's posOverflow field, since that logic seems
pretty useless given that portalPos is now always 64 bits.
The user-visible results are that command tags for SELECT etc will
correctly report tuple counts larger than 4G, as will plpgsql's GET
GET DIAGNOSTICS ... ROW_COUNT command. Queries processing more tuples
than that are still not exactly the norm, but they're becoming more
common.
Most values associated with FETCH/MOVE distances, such as PortalRun's count
argument and the count argument of most SPI functions that have one, remain
declared as "long". It's not clear whether it would be worth promoting
those to int64; but it would definitely be a large dollop of additional
API churn on top of this, and it would only help 32-bit platforms which
seem relatively less likely to see any benefit.
Andreas Scherbaum, reviewed by Christian Ullrich, additional hacking by me
Commit d1b7c1ffe7 introduced a mechanism
for serializing a ParamListInfo structure to be passed to a parallel
worker. However, this mechanism failed to handle external expanded
values, as pointed out by Noah Misch. Repair.
Moreover, plpgsql_param_fetch requires adjustment because the
serialization mechanism needs it to skip evaluating unused parameters
just as we would do when it is called from copyParamList, but params
== estate->paramLI in that case. To fix, make the bms_is_member test
in that function unconditional.
Finally, have setup_param_list set a new ParamListInfo field,
paramMask, to the parameters actually used in the expression, so that
we don't try to fetch those that are not needed when serializing a
parameter list. This isn't necessary for correctness, but it makes
the performance of the parallel executor code comparable to what we
do for cases involving cursors.
Design suggestions and extensive review by Noah Misch. Patch by me.
Commit 924bcf4f16 introduced a framework
for parallel computation in PostgreSQL that makes most but not all
built-in functions safe to execute in parallel mode. In order to have
parallel query, we'll need to be able to determine whether that query
contains functions (either built-in or user-defined) that cannot be
safely executed in parallel mode. This requires those functions to be
labeled, so this patch introduces an infrastructure for that. Some
functions currently labeled as safe may need to be revised depending on
how pending issues related to heavyweight locking under paralllelism
are resolved.
Parallel plans can't be used except for the case where the query will
run to completion. If portal execution were suspended, the parallel
mode restrictions would need to remain in effect during that time, but
that might make other queries fail. Therefore, this patch introduces
a framework that enables consideration of parallel plans only when it
is known that the plan will be run to completion. This probably needs
some refinement; for example, at bind time, we do not know whether a
query run via the extended protocol will be execution to completion or
run with a limited fetch count. Having the client indicate its
intentions at bind time would constitute a wire protocol break. Some
contexts in which parallel mode would be safe are not adjusted by this
patch; the default is not to try parallel plans except from call sites
that have been updated to say that such plans are OK.
This commit doesn't introduce any parallel paths or plans; it just
provides a way to determine whether they could potentially be used.
I'm committing it on the theory that the remaining parallel sequential
scan patches will also get committed to this release, hopefully in the
not-too-distant future.
Robert Haas and Amit Kapila. Reviewed (in earlier versions) by Noah
Misch.
Remove the code in plpgsql that suppressed the innermost line of CONTEXT
for messages emitted by RAISE commands. That was never more than a quick
backwards-compatibility hack, and it's pretty silly in cases where the
RAISE is nested in several levels of function. What's more, it violated
our design theory that verbosity of error reports should be controlled
on the client side not the server side.
To alleviate the resulting noise increase, introduce a feature in libpq
and psql whereby the CONTEXT field of messages can be suppressed, either
always or only for non-error messages. Printing CONTEXT for errors only
is now their default behavior.
The actual code changes here are pretty small, but the effects on the
regression test outputs are widespread. I had to edit some of the
alternative expected outputs by hand; hopefully the buildfarm will soon
find anything I fat-fingered.
In passing, fix up (again) the output line counts in psql's various
help displays. Add some commentary about how to verify them.
Pavel Stehule, reviewed by Petr Jelínek, Jeevan Chalke, and others
With a bit of tweaking of the compile namestack data structure, we can
verify at compile time whether a CONTINUE or EXIT is legal. This is
surely better than leaving it to runtime, both because earlier is better
and because we can issue a proper error pointer. Also, we can get rid
of the ad-hoc old way of detecting the problem, which only took care of
CONTINUE not EXIT.
Jim Nasby, adjusted a bit by me
My expanded-objects patch (commit 1dc5ebc907) included code to make
plpgsql pass expanded-object variables as R/W pointers to certain functions
that are trusted for modifying such variables in-place. However, that
optimization got broken by commit 6c82d8d1fd, which arranged to share
a single ParamListInfo across most expressions evaluated by a plpgsql
function. We don't want a R/W pointer to be passed to other functions
just because we decided one function was safe! Fortunately, the breakage
was in the other direction, of never passing a R/W pointer at all, because
we'd always have pre-initialized the shared array slot with a R/O pointer.
So it was still functionally correct, but we were back to O(N^2)
performance for repeated use of "a := a || x". To fix, force an unshared
param array to be used when the R/W param optimization is active.
Commit 6c82d8d1fd is in HEAD only, so no need for a back-patch.
DO blocks use private simple_eval_estates to avoid intra-transaction memory
leakage, cf commit c7b849a89. I had forgotten about that while writing
commit 0fc94a5ba, but it means that expression execution trees created
within a DO block disappear immediately on exiting the DO block, and hence
can't safely be linked into plpgsql's session-wide cast hash table.
To fix, give a DO block a private cast hash table to go with its private
simple_eval_estate. This is less efficient than one could wish, since
DO blocks can no longer share any cast lookup work with other plpgsql
execution, but it shouldn't be too bad; in any case it's no worse than
what happened in DO blocks before commit 0fc94a5ba.
Per bug #13571 from Feike Steenbergen. Preliminary analysis by
Oleksandr Shulgin.
In commit 1345cc67bb, I introduced caching
of expressions representing type-cast operations into plpgsql. However,
I supposed that I could cache both the expression trees and the evaluation
state trees derived from them for the life of the session. This doesn't
work, because we execute the expressions in plpgsql's simple_eval_estate,
which has an ecxt_per_query_memory that is only transaction-lifespan.
Therefore we can end up putting pointers into the evaluation state tree
that point to transaction-lifespan memory; in particular this happens if
the cast expression calls a SQL-language function, as reported by Geoff
Winkless.
The minimum-risk fix seems to be to treat the state trees the same way
we do for "simple expression" trees in plpgsql, ie create them in the
simple_eval_estate's ecxt_per_query_memory, which means recreating them
once per transaction.
Since I had to introduce bookkeeping overhead for that anyway, I bought
back some of the added cost by sharing the read-only expression trees
across all functions in the session, instead of using a per-function
table as originally. The simple-expression bookkeeping takes care of
the recursive-usage risk that I was concerned about avoiding before.
At some point we should take a harder look at how all this works,
and see if we can't reduce the amount of tree reinitialization needed.
But that won't happen for 9.5.
This builds on commit 21dcda2713 by keeping
a plpgsql function's shared ParamListInfo's entries for simple variables
(PLPGSQL_DTYPE_VARs) valid at all times. That adds a few cycles to each
assignment to such variables, but saves significantly more cycles each time
they are used; so except in the pathological case of many dead stores, this
should always be a win. Initial testing says it's good for about a 10%
speedup of simple calculations; more in large functions with many datums.
We can't use this method for row/record references unfortunately, so what
we do for those is reset those ParamListInfo slots after use; which we
can skip doing unless some of them were actually evaluated during the
previous evaluation call. So this should frequently be a win as well,
while worst case is that it's similar cost to the previous approach.
Also, closer study suggests that the previous method of instantiating a
new ParamListInfo array per evaluation is actually probably optimal for
cursor-opening executor calls. The reason is that whatever is visible in
the array is going to get copied into the cursor portal via copyParamList.
So if we used the function's main ParamListInfo for those calls, we'd end
up with all of its DTYPE_VAR vars getting copied, which might well include
large pass-by-reference values that the cursor actually has no need for.
To avoid a possible net degradation in cursor cases, go back to creating
and filling a private ParamListInfo in those cases (which therefore will be
exactly the same speed as before 21dcda2713). We still get some benefit
out of this though, because this approach means that we only have to defend
against copyParamList's try-to-fetch-every-slot behavior in the case of an
unshared ParamListInfo; so plpgsql_param_fetch() can skip testing
expr->paramnos in the common case.
To ensure that the main ParamListInfo's image of a DTYPE_VAR datum is
always valid, all assignments to such variables are now funneled through
assign_simple_var(). But this makes for cleaner and shorter code anyway.
In commit 9e3ad1aac5 I modified plpgsql
to use exec_stmt_return's simple-variables fast path in more cases.
However, I overlooked that there are really two different return
conventions in use here, depending on whether estate->retistuple is true,
and the existing fast-path code had only bothered to handle one of them.
So trying to return a scalar in a function returning composite, or vice
versa, could lead to unexpected error messages (typically "cache lookup
failed for type 0") or to a null-pointer-dereference crash.
In the DTYPE_VAR case, we can just throw error if retistuple is true,
corresponding to what happens in the general-expression code path that was
being used previously. (Perhaps someday both of these code paths should
attempt a coercion, but today is not that day.)
In the REC and ROW cases, just hand the problem to exec_eval_datum()
when not retistuple. Also clean up the ROW coding slightly so it looks
more like exec_eval_datum().
The previous commit also caused exec_stmt_return_next() to be used in
more cases, but that code seems to be OK as-is.
Per off-list report from Serge Rielau. This bug is new in 9.5 so no need
to back-patch.
This patch introduces the ability for complex datatypes to have an
in-memory representation that is different from their on-disk format.
On-disk formats are typically optimized for minimal size, and in any case
they can't contain pointers, so they are often not well-suited for
computation. Now a datatype can invent an "expanded" in-memory format
that is better suited for its operations, and then pass that around among
the C functions that operate on the datatype. There are also provisions
(rudimentary as yet) to allow an expanded object to be modified in-place
under suitable conditions, so that operations like assignment to an element
of an array need not involve copying the entire array.
The initial application for this feature is arrays, but it is not hard
to foresee using it for other container types like JSON, XML and hstore.
I have hopes that it will be useful to PostGIS as well.
In this initial implementation, a few heuristics have been hard-wired
into plpgsql to improve performance for arrays that are stored in
plpgsql variables. We would like to generalize those hacks so that
other datatypes can obtain similar improvements, but figuring out some
appropriate APIs is left as a task for future work. (The heuristics
themselves are probably not optimal yet, either, as they sometimes
force expansion of arrays that would be better left alone.)
Preliminary performance testing shows impressive speed gains for plpgsql
functions that do element-by-element access or update of large arrays.
There are other cases that get a little slower, as a result of added array
format conversions; but we can hope to improve anything that's annoyingly
bad. In any case most applications should see a net win.
Tom Lane, reviewed by Andres Freund
Obsoleted by commit 21dcda2713, but I missed
seeing the cross-reference in the comments for exec_eval_integer().
Also improve the cross-reference in the comments for exec_eval_cleanup().
setup_param_list() was allocating a fresh ParamListInfo for each query or
expression evaluation requested by a plpgsql function. There was probably
once good reason to do it like that, but for a long time we've had a
convention that there's a one-to-one mapping between the function's
PLpgSQL_datum array and the ParamListInfo slots, which means that a single
ParamListInfo can serve all the function's evaluation requests: the data
that would need to be passed is the same anyway.
In this patch, we retain the pattern of zeroing out the ParamListInfo
contents during each setup_param_list() call, because some of the slots may
be stale and we don't know exactly which ones. So this patch only saves a
palloc/pfree per evaluation cycle and nothing more; still, that seems to be
good for a couple percent overall speedup on simple-arithmetic type
statements. In future, though, we might be able to improve matters still
more by managing the param array contents more carefully.
Also, unify the former use of estate->cur_expr with that of
paramLI->parserSetupArg; they both were used to point to the active
expression, so we can combine the variables into just one.
I had thought that there was no need to maintain separate cache entries
for different source typmods, but further experimentation shows that there
is an advantage to doing so in some cases. In particular, if a domain has
a typmod (say, "CREATE DOMAIN d AS numeric(20,0)"), failing to notice the
source typmod leads to applying a length-coercion step even when the
source has the correct typmod.
This is because can_coerce_type thinks that RECORD can be cast to any
composite type, but coerce_record_to_complex only works for inputs that are
RowExprs or whole-row Vars, so we get a hard failure on a CaseTestExpr.
Perhaps these corner cases ought to be fixed so that coerce_to_target_type
actually returns NULL as per its specification, rather than failing ...
but for the moment an extra check here is the path of least resistance.
plpgsql's historical method for converting datatypes during assignments was
to apply the source type's output function and then the destination type's
input function. Aside from being miserably inefficient in most cases, this
method failed outright in many cases where a user might expect it to work;
an example is that "declare x int; ... x := 3.9;" would fail, not round the
value to 4.
Instead, let's convert by applying the appropriate assignment cast whenever
there is one. To avoid breaking compatibility unnecessarily, fall back to
the I/O conversion method if there is no assignment cast.
So far as I can tell, there is just one case where this method produces a
different result than the old code in a case where the old code would not
have thrown an error. That is assignment of a boolean value to a string
variable (type text, varchar, or bpchar); the old way gave boolean's output
representation, ie 't'/'f', while the new way follows the behavior of the
bool-to-text cast and so gives 'true' or 'false'. This will need to be
called out as an incompatibility in the 9.5 release notes.
Aside from handling many conversion cases more sanely, this method is
often significantly faster than the old way. In part that's because
of more effective caching of the conversion info.
The main value of this change is to avoid expensive I/O conversions when
assigning to a variable that has a typmod specification, if the value
to be assigned is already known to have the right typmod. This is
particularly valuable for arrays with typmod specifications; formerly,
in an assignment to an array element the entire array would invariably
get put through double I/O conversion to check the typmod, to absolutely
no purpose since we'd already properly coerced the new element value.
Extracted from my "expanded arrays" patch; this seems worth committing
separately, whatever becomes of that patch, since it's really an
independent issue.
As long as we're changing the function signatures, take the opportunity
to rationalize the argument lists of exec_assign_value, exec_cast_value,
and exec_simple_cast_value; that is, put the arguments into a saner order,
and get rid of the bizarre choice to pass exec_assign_value's isNull flag
by reference.
"RETURN SQLERRM" prompted plpgsql_exec_function() to read from freed
memory. Back-patch to 9.0 (all supported versions). Little code ran
between the premature free and the read, so non-assert builds are
unlikely to witness user-visible consequences.
exec_stmt_return() and exec_stmt_return_next() have fast-path code for
handling a simple variable reference (i.e. "return var") without going
through the full expression evaluation machinery. For some reason,
pl_gram.y was under the impression that this fast path only applied for
record/row variables; but in reality code for handling regular scalar
variables has been there all along. Adjusting the logic to allow that
code to be used actually results in a net savings of code in pl_gram.y
(by eliminating some redundancy), and it buys a measurable though not
very impressive amount of speedup.
Noted while fooling with my expanded-array patch, wherein this makes a much
bigger difference because it enables returning an expanded array variable
without an extra flattening step. But AFAICS this is a win regardless,
so commit it separately.
The four functions array_ref, array_set, array_get_slice, array_set_slice
have traditionally declared their array inputs and results as being of type
"ArrayType *". This is a lie, and has been since Berkeley days, because
they actually also support "fixed-length array" types such as "name" and
"point"; not to mention that the inputs could be toasted. These values
should be declared Datum instead to avoid confusion. The current coding
already risks possible misoptimization by compilers, and it'll get worse
when "expanded" array representations become a valid alternative.
However, there's a fair amount of code using array_ref and array_set with
arrays that *are* known to be ArrayType structures, and there might be more
such places in third-party code. Rather than cluttering those call sites
with PointerGetDatum/DatumGetArrayTypeP cruft, what I did was to rename the
existing functions to array_get_element/array_set_element, fix their
signatures, then reincarnate array_ref/array_set as backwards compatibility
wrappers.
array_get_slice/array_set_slice have no such constituency in the core code,
and probably not in third-party code either, so I just changed their APIs.
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
The number of % parameter markers in RAISE statement should match the number
of parameters given. We used to check that at execution time, but we have
all the information needed at compile time, so let's check it at compile
time instead. It's generally better to find mistakes earlier.
Marko Tiikkaja, reviewed by Fabien Coelho
If we have an array of records stored on disk, the individual record fields
cannot contain out-of-line TOAST pointers: the tuptoaster.c mechanisms are
only prepared to deal with TOAST pointers appearing in top-level fields of
a stored row. The same applies for ranges over composite types, nested
composites, etc. However, the existing code only took care of expanding
sub-field TOAST pointers for the case of nested composites, not for other
structured types containing composites. For example, given a command such
as
UPDATE tab SET arraycol = ARRAY[(ROW(x,42)::mycompositetype] ...
where x is a direct reference to a field of an on-disk tuple, if that field
is long enough to be toasted out-of-line then the TOAST pointer would be
inserted as-is into the array column. If the source record for x is later
deleted, the array field value would become a dangling pointer, leading
to errors along the line of "missing chunk number 0 for toast value ..."
when the value is referenced. A reproducible test case for this was
provided by Jan Pecek, but it seems likely that some of the "missing chunk
number" reports we've heard in the past were caused by similar issues.
Code-wise, the problem is that PG_DETOAST_DATUM() is not adequate to
produce a self-contained Datum value if the Datum is of composite type.
Seen in this light, the problem is not just confined to arrays and ranges,
but could also affect some other places where detoasting is done in that
way, for example form_index_tuple().
I tried teaching the array code to apply toast_flatten_tuple_attribute()
along with PG_DETOAST_DATUM() when the array element type is composite,
but this was messy and imposed extra cache lookup costs whether or not any
TOAST pointers were present, indeed sometimes when the array element type
isn't even composite (since sometimes it takes a typcache lookup to find
that out). The idea of extending that approach to all the places that
currently use PG_DETOAST_DATUM() wasn't attractive at all.
This patch instead solves the problem by decreeing that composite Datum
values must not contain any out-of-line TOAST pointers in the first place;
that is, we expand out-of-line fields at the point of constructing a
composite Datum, not at the point where we're about to insert it into a
larger tuple. This rule is applied only to true composite Datums, not
to tuples that are being passed around the system as tuples, so it's not
as invasive as it might sound at first. With this approach, the amount
of code that has to be touched for a full solution is greatly reduced,
and added cache lookup costs are avoided except when there actually is
a TOAST pointer that needs to be inlined.
The main drawback of this approach is that we might sometimes dereference
a TOAST pointer that will never actually be used by the query, imposing a
rather large cost that wasn't there before. On the other side of the coin,
if the field value is used multiple times then we'll come out ahead by
avoiding repeat detoastings. Experimentation suggests that common SQL
coding patterns are unaffected either way, though. Applications that are
very negatively affected could be advised to modify their code to not fetch
columns they won't be using.
In future, we might consider reverting this solution in favor of detoasting
only at the point where data is about to be stored to disk, using some
method that can drill down into multiple levels of nested structured types.
That will require defining new APIs for structured types, though, so it
doesn't seem feasible as a back-patchable fix.
Note that this patch changes HeapTupleGetDatum() from a macro to a function
call; this means that any third-party code using that macro will not get
protection against creating TOAST-pointer-containing Datums until it's
recompiled. The same applies to any uses of PG_RETURN_HEAPTUPLEHEADER().
It seems likely that this is not a big problem in practice: most of the
tuple-returning functions in core and contrib produce outputs that could
not possibly be toasted anyway, and the same probably holds for third-party
extensions.
This bug has existed since TOAST was invented, so back-patch to all
supported branches.
plpgsql likes to cache query plans and simple-expression execution state
trees across calls. This is a considerable win for multiple executions
of the same function. However, it's useless for DO blocks, since by
definition those are executed only once and discarded. Nonetheless,
we were allowing a DO block's expression execution trees to survive
until end of transaction, resulting in a significant intra-transaction
memory leak, as reported by Yeb Havinga. Worse, if the DO block exited
with an error, the compiled form of the block's code was leaked till
end of session --- along with subsidiary plancache entries.
To fix, make DO blocks keep their expression execution trees in a private
EState that's deleted at exit from the block, and add a PG_TRY block
to plpgsql_inline_handler to make sure that memory cleanup happens
even on error exits. Also add a regression test covering error handling
in a DO block, because my first try at this broke that. (The test is
not meant to prove that we don't leak memory anymore, though it could
be used for that with a much larger loop count.)
Ideally we'd back-patch this into all versions supporting DO blocks;
but the patch needs to add a field to struct PLpgSQL_execstate, and that
would break ABI compatibility for third-party plugins such as the plpgsql
debugger. Given the small number of complaints so far, fixing this in
HEAD only seems like an acceptable choice.
This option provides more detailed error messages when STRICT is used
and the number of rows returned is not one.
Marko Tiikkaja, reviewed by Ian Lawrence Barwick
plpgsql often just remembers SPI-result tuple tables in local variables,
and has no mechanism for freeing them if an ereport(ERROR) causes an escape
out of the execution function whose local variable it is. In the original
coding, that wasn't a problem because the tuple table would be cleaned up
when the function's SPI context went away during transaction abort.
However, once plpgsql grew the ability to trap exceptions, repeated
trapping of errors within a function could result in significant
intra-function-call memory leakage, as illustrated in bug #8279 from
Chad Wagner.
We could fix this locally in plpgsql with a bunch of PG_TRY/PG_CATCH
coding, but that would be tedious, probably slow, and prone to bugs of
omission; moreover it would do nothing for similar risks elsewhere.
What seems like a better plan is to make SPI itself responsible for
freeing tuple tables at subtransaction abort. This patch attacks the
problem that way, keeping a list of live tuple tables within each SPI
function context. Currently, such freeing is automatic for tuple tables
made within the failed subtransaction. We might later add a SPI call to
mark a tuple table as not to be freed this way, allowing callers to opt
out; but until someone exhibits a clear use-case for such behavior, it
doesn't seem worth bothering.
A very useful side-effect of this change is that SPI_freetuptable() can
now defend itself against bad calls, such as duplicate free requests;
this should make things more robust in many places. (In particular,
this reduces the risks involved if a third-party extension contains
now-redundant SPI_freetuptable() calls in error cleanup code.)
Even though the leakage problem is of long standing, it seems imprudent
to back-patch this into stable branches, since it does represent an API
semantics change for SPI users. We'll patch this in 9.3, but live with
the leakage in older branches.
This adds the ability to get the call stack as a string from within a
PL/PgSQL function, which can be handy for logging to a table, or to
include in a useful message to an end-user.
Pavel Stehule, reviewed by Rushabh Lathia and rather heavily whacked
around by Stephen Frost.
Specifically, permit attaching them to the error in RAISE and retrieving
them from a caught error in GET STACKED DIAGNOSTICS. RAISE enforces
nothing about the content of the fields; for its purposes, they are just
additional string fields. Consequently, clarify in the protocol and
libpq documentation that the usual relationships between error fields,
like a schema name appearing wherever a table name appears, are not
universal. This freedom has other applications; consider a FDW
propagating an error from an RDBMS having no schema support.
Back-patch to 9.3, where core support for the error fields was
introduced. This prevents the confusion of having a release where libpq
exposes the fields and PL/pgSQL does not.
Pavel Stehule, lexical revisions by Noah Misch.
Currently it's only possible for loadable modules to get control during
post-commit cleanup of a transaction. That doesn't work too well if they
want to do something that could throw an error; for example, an FDW might
need to issue a remote commit, which could well fail. To improve matters,
extend the existing APIs for XactCallback and SubXactCallback functions
to provide new pre-commit events for this purpose.
The release notes will need to mention that existing callback functions
should be checked to make sure they don't do something unwanted when one
of the new event types occurs. In the examples within our source tree,
contrib/sepgsql was fine but plpgsql had been a bit too cute.
exec_simple_check_plan and exec_eval_simple_expr attempted to call
GetCachedPlan directly. This meant that if an error was thrown during
planning, the resulting context traceback would not include the line
normally contributed by _SPI_error_callback. This is already inconsistent,
but just to be really odd, a re-execution of the very same expression
*would* show the additional context line, because we'd already have cached
the plan and marked the expression as non-simple.
The problem is easy to demonstrate in 9.2 and HEAD because planning of a
cached plan doesn't occur at all until GetCachedPlan is done. In earlier
versions, it could only be an issue if initial planning had succeeded, then
a replan was forced (already somewhat improbable for a simple expression),
and the replan attempt failed. Since the issue is mainly cosmetic in older
branches anyway, it doesn't seem worth the risk of trying to fix it there.
It is worth fixing in 9.2 since the instability of the context printout can
affect the results of GET STACKED DIAGNOSTICS, as per a recent discussion
on pgsql-novice.
To fix, introduce a SPI function that wraps GetCachedPlan while installing
the correct callback function. Use this instead of calling GetCachedPlan
directly from plpgsql.
Also introduce a wrapper function for extracting a SPI plan's
CachedPlanSource list. This lets us stop including spi_priv.h in
pl_exec.c, which was never a very good idea from a modularity standpoint.
In passing, fix a similar inconsistency that could occur in SPI_cursor_open,
which was also calling GetCachedPlan without setting up a context callback.
For some reason lost in the mists of prehistory, RETURN was only coded to
allow a simple reference to a composite variable when the function's return
type is composite. Allow an expression instead, while preserving the
efficiency of the original code path in the case where the expression is
indeed just a composite variable's name. Likewise for RETURN NEXT.
As is true in various other places, the supplied expression must yield
exactly the number and data types of the required columns. There was some
discussion of relaxing that for pl/pgsql, but no consensus yet, so this
patch doesn't address that.
Asif Rehman, reviewed by Pavel Stehule
This reduces unnecessary exposure of other headers through htup.h, which
is very widely included by many files.
I have chosen to move the function prototypes to the new file as well,
because that means htup.h no longer needs to include tupdesc.h. In
itself this doesn't have much effect in indirect inclusion of tupdesc.h
throughout the tree, because it's also required by execnodes.h; but it's
something to explore in the future, and it seemed best to do the htup.h
change now while I'm busy with it.
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
The Solaris Studio compiler warns about these instances, unlike more
mainstream compilers such as gcc. But manual inspection showed that
the code is clearly not reachable, and we hope no worthy compiler will
complain about removing this code.
An incorrect and entirely unnecessary "safety check" in exec_stmt_getdiag()
caused the code to treat an assignment to a variable with dno zero as a
no-op. Unfortunately, that's a perfectly valid dno. This has been broken
since GET DIAGNOSTICS was invented. It's not terribly surprising that the
bug went unnoticed for so long, since in most cases you probably wouldn't
use the function's first-created variable (normally its first parameter)
as a GET DIAGNOSTICS target. Nonetheless, it's broken. Per bug #6551
from Adam Buraczewski.
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
Datatype I/O functions are allowed to leak memory in CurrentMemoryContext,
since they are generally called in short-lived contexts. However, plpgsql
calls such functions for purposes of type conversion, and was calling them
in its procedure context. Therefore, any leaked memory would not be
recovered until the end of the plpgsql function. If such a conversion
was done within a loop, quite a bit of memory could get consumed. Fix by
calling such functions in the transient "eval_econtext", and adjust other
logic to match. Back-patch to all supported versions.
Andres Freund, Jan Urbański, Tom Lane
Don't quote the output of format_procedure(); it's already quoted quite
enough. Remove the fn_name field, which was now just dead weight. Fix
remaining expected-output files.
The original coding was
var->value = (Datum) state;
which is bogus, and then in commit 2f0f7b4bce
it was "corrected" to
var->value = PointerGetDatum(state);
which is a faithful translation but still wrong.
This seems purely cosmetic, though, so no need for a back-patch.
Pavel Stehule
The original implementation of ELSIF in plpgsql converted the construct
into nested simple IF statements. This was prone to stack overflow with
long ELSIF lists, in two different ways. First, it's difficult to generate
the parsetree without using right-recursion in the bison grammar, and
that's prone to parser stack overflow since nothing can be reduced until
the whole list has been read. Second, we'd recurse during execution, thus
creating an unnecessary risk of execution-time stack overflow. Rewrite
so that the ELSIF list is represented as a flat list, scanned via iteration
not recursion, and generated through left-recursion in the grammar.
Per a gripe from Håvard Kongsgård.
plpgsql's exec_stmt_execsql was Assert'ing that a CachedPlanSource was
is_valid immediately after exec_prepare_plan. The risk factor in this case
is that after building the prepared statement, exec_prepare_plan calls
exec_simple_check_plan, which might try to generate a generic plan --- and
with CLOBBER_CACHE_ALWAYS or other unusual causes of invalidation, that
could result in an invalidation. However, that path could only be taken
for a SELECT query, for which we need not set mod_stmt. So in this case
I think it's best to just remove the Assert; it's okay to look at a
slightly-stale querytree for what we need here. Per buildfarm testing.
Now that a NULL ParamListInfo pointer causes significantly different
behavior in plancache.c, be sure to pass it that way when the expression
is known not to reference any plpgsql variables. Saves a few setup
cycles anyway.
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 is more SQL-spec-compliant, more easily extensible, and better
performing than the old method of inventing special variables.
Pavel Stehule, reviewed by Shigeru Hanada and David Wheeler
There may be some other places where we should use errdetail_internal,
but they'll have to be evaluated case-by-case. This commit just hits
a bunch of places where invoking gettext is obviously a waste of cycles.
Historically we didn't do this, even though we had the information, because
plpgsql passed its Params via SPI APIs that only include type OIDs not
typmods. Now that plpgsql uses parser callbacks to create Params, it's
easy to insert the right typmod. This should generally result in lower
surprise factors, because a plpgsql variable that is declared with a typmod
will now work more like a table column with the same typmod. In particular
it's the "right" way to fix bug #6020, in which plpgsql's attempt to return
an anonymous record type is defeated by stricter record-type matching
checks that were added in 9.0. However, it's not impossible that this
could result in subtle behavioral changes that could break somebody's
existing plpgsql code, so I'm afraid to back-patch this change into
released branches. In those branches we'll have to lobotomize the
record-type checks instead.
This warning is new in gcc 4.6 and part of -Wall. This patch cleans
up most of the noise, but there are some still warnings that are
trickier to remove.
Make plpgsql treat the input collation as a polymorphism variable, so
that we cache separate plans for each input collation that's used in a
particular session, as per recent discussion. Propagate the input
collation to all collatable input parameters.
I chose to also propagate the input collation to all declared variables of
collatable types, which is a bit more debatable but seems to be necessary
for non-astonishing behavior. (Copying a parameter into a separate local
variable shouldn't result in a change of behavior, for example.) There is
enough infrastructure here to support declaring a collation for each local
variable to override that default, but I thought we should wait to see what
the field demand is before adding such a feature.
In passing, remove exec_get_rec_fieldtype(), which wasn't used anywhere.
Documentation patch to follow.
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.
(I'm not entirely sure that we've finished bikeshedding the syntax details,
but the functionality seems OK.)
Pavel Stehule, reviewed by Stephen Frost and Tom Lane
Instead of using ExecPrepareExpr, call ExecInitExpr. The net change here
is that we don't apply expression_planner() to the expression tree. There
is no need to do so, because that tree is extracted from a fully planned
plancache entry, so all the needed work is already done. This reduces
the setup costs by about a factor of 2 according to some simple tests.
Oversight noted while fooling around with the simple-expression code for
previous fix.
In general, expression execution state trees aren't re-entrantly usable,
since functions can store private state information in them.
For efficiency reasons, plpgsql tries to cache and reuse state trees for
"simple" expressions. It can get away with that most of the time, but it
can fail if the state tree is dirty from a previous failed execution (as
in an example from Alvaro) or is being used recursively (as noted by me).
Fix by tracking whether a state tree is in use, and falling back to the
"non-simple" code path if so. This results in a pretty considerable speed
hit when the non-simple path is taken, but the available alternatives seem
even more unpleasant because they add overhead in the simple path. Per
idea from Heikki.
Back-patch to all supported branches.
This patch eliminates various bizarre behaviors caused by sloppy thinking
about the difference between a domain type and its underlying array type.
In particular, the operation of updating one element of such an array
has to be considered as yielding a value of the underlying array type,
*not* a value of the domain, because there's no assurance that the
domain's CHECK constraints are still satisfied. If we're intending to
store the result back into a domain column, we have to re-cast to the
domain type so that constraints are re-checked.
For similar reasons, such a domain can't be blindly matched to an ANYARRAY
polymorphic parameter, because the polymorphic function is likely to apply
array-ish operations that could invalidate the domain constraints. For the
moment, we just forbid such matching. We might later wish to insert an
automatic downcast to the underlying array type, but such a change should
also change matching of domains to ANYELEMENT for consistency.
To ensure that all such logic is rechecked, this patch removes the original
hack of setting a domain's pg_type.typelem field to match its base type;
the typelem will always be zero instead. In those places where it's really
okay to look through the domain type with no other logic changes, use the
newly added get_base_element_type function in place of get_element_type.
catversion bumped due to change in pg_type contents.
Per bug #5717 from Richard Huxton and subsequent discussion.
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.
Various places were testing TRIGGER_FIRED_BEFORE() where what they really
meant was !TRIGGER_FIRED_AFTER(), or vice versa. This needs to be cleaned
up because there are about to be more than two possible states.
We might want to note this in the 9.1 release notes as something for
trigger authors to double-check.
For consistency's sake I also changed some places that assumed that
TRIGGER_FIRED_FOR_ROW and TRIGGER_FIRED_FOR_STATEMENT are necessarily
mutually exclusive; that's not in immediate danger of breaking, but
it's still sloppier than it should be.
Extracted from Dean Rasheed's patch for triggers on views. I'm committing
this separately since it's an identifiable separate issue, and is the
only reason for the patch to touch most of these particular files.
It's not clear if this situation can occur in plpgsql other than via the
EXECUTE USING case Heikki illustrated, which I will shortly close off.
However, ignoring the intoClause if it's there is surely wrong, so let's
patch it for safety.
Backpatch to 8.3, which is as far back as this code has a PlannedStmt
to deal with. There might be another way to make an equivalent test
before that, but since this is just preventing hypothetical bugs,
I'm not going to obsess about it.
pointed out, it would need a 2nd pass after the whole query is processed to
correctly check that an unknown Param is coerced to the same target type
everywhere. Adding the 2nd pass would add a lot more code, which doesn't
seem worth the risk given that there isn't much of a use case for passing
unknown Params in the first place. The code would work without that check,
but it might be confusing and the behavior would be different from the
varparams case.
Instead, just coerce all unknown params in a PL/pgSQL USING clause to text.
That's simple, and is usually what users expect.
Revert the patch in CVS HEAD and master, and backpatch the new solution to
8.4. Unlike the previous solution, this applies easily to 8.4 too.
expressions. We need to deal with this when handling subscripts in an array
assignment, and also when catching an exception. In an Assert-enabled build
these omissions led to Assert failures, but I think in a normal build the
only consequence would be short-term memory leakage; which may explain why
this wasn't reported from the field long ago.
Back-patch to all supported versions. 7.4 doesn't have exceptions, but
otherwise these bugs go all the way back.
Heikki Linnakangas and Tom Lane
can be caught in the same places that could catch an ordinary RAISE ERROR
in the same location. The previous coding insisted on throwing the error
from the block containing the active exception handler; which is arguably
more surprising, and definitely unlike Oracle's behavior.
Not back-patching, since this is a pretty obscure corner case. The risk
of breaking somebody's code in a minor version update seems to outweigh
any possible benefit.
Piyush Newe, reviewed by David Fetter
being used in a PL/pgSQL FOR loop is closed was inadequate, as Tom Lane
pointed out. The bug affects FOR statement variants too, because you can
close an implicitly created cursor too by guessing the "<unnamed portal X>"
name created for it.
To fix that, "pin" the portal to prevent it from being dropped while it's
being used in a PL/pgSQL FOR loop. Backpatch all the way to 7.4 which is
the oldest supported version.
might close the cursor, rendering the Portal pointer to it invalid.
Closing the cursor in the middle of the loop is not a very sensible thing
to do, but we must handle it gracefully and throw an error instead of
crashing.
even when the expression is a query that returns no rows.
So far as I can tell, the only caller that actually fails when a garbage
OID is returned is exec_stmt_case(), which is new in 8.4 --- in all other
cases, we might make a useless trip through casting logic, but we won't
fail since the isnull flag will be set. Hence, backpatch only to 8.4,
just in case there are apps out there that aren't expecting an error to
be thrown if the query returns more or less than one column. (Which seems
unlikely, since the error would be thrown if the query ever did return a
row; but it's possible there's some never-exercised code out there.)
Per report from Mario Splivalo.
that happens to be composite itself. Per bug #5314 from Oleg Serov.
Backpatch to 8.0 --- 7.4 has got too many other shortcomings in
composite-type support to make this worth worrying about in that branch.
This is the last EXECUTE-like plpgsql statement that was missing
the capability of inserting parameter values via USING.
Pavel Stehule, reviewed by Itagaki Takahiro
PL/pgSQL function within an exception handler. Make sure we use the right
resource owner when we create the tuplestore to hold returned tuples.
Simplify tuplestore API so that the caller doesn't need to be in the right
memory context when calling tuplestore_put* functions. tuplestore.c
automatically switches to the memory context used when the tuplestore was
created. Tuplesort was already modified like this earlier. This patch also
removes the now useless MemoryContextSwitch calls from callers.
Report by Aleksei on pgsql-bugs on Dec 22 2009. Backpatch to 8.1, like
the previous patch that broke this.
like the core parser's code. In particular, track locations at the character
rather than line level during parsing, allowing many more parse-time error
conditions to be reported with precise error pointers rather than just
"near line N".
Also, exploit the fact that we no longer need to substitute $N for variable
references by making extracted SQL queries and expressions be exact copies
of subranges of the function text, rather than having random whitespace
changes within them. This makes it possible to directly map parse error
positions from the core parser onto positions in the function text, which
lets us report them without the previous kluge of showing the intermediate
internal-query form. (Later it might be good to do that for core
parse-analysis errors too, but this patch is just touching plpgsql's
lexer/parser, not what happens at runtime.)
In passing, make plpgsql's lexer use palloc not malloc.
These changes make plpgsql's parse-time error reports noticeably nicer
(as illustrated by the regression test changes), and will also simplify
the planned removal of plpgsql's separate lexer by reducing the impedance
mismatch between what it does and what the core lexer does.
into SQL expressions, to using the newly added parser callback hooks.
This allows us to do the substitutions in a more semantically-aware way:
a variable reference will only be recognized where it can validly go,
ie, a place where a column value or parameter would be legal, instead of
the former behavior that would replace any textual match including
table names and column aliases (leading to syntax errors later on).
A release-note-worthy fine point is that plpgsql variable names that match
fully-reserved words will now need to be quoted.
This commit preserves the former behavior that variable references take
precedence over any possible match to a column name. The infrastructure
is in place to support the reverse precedence or throwing an error on
ambiguity, but those behaviors aren't accessible yet.
Most of the code changes here are associated with making the namespace
data structure persist so that it can be consulted at runtime, instead
of throwing it away at the end of initial function parsing.
The plpgsql scanner is still doing name lookups, but that behavior is
now irrelevant for SQL expressions. A future commit will deal with
removing unnecessary lookups.
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.
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.
Peter Eisentraut
Tom Lane
Bruce Momjian
Robert Haas
Andres Freund
Kevin Grittner
Magnus Hagander
Alvaro Herrera
Noah Misch
Heikki Linnakangas
Stephen Frost
Joe Conway
Itagaki Takahiro