As mentioned in 8268e41aca, pgss_ProcessUtility() may free the
PlannedStmt after an internal ROLLBACK. This commit sets the
PlannedStmt "pstmt" to NULL once it is no longer safe to rely on it,
making bugs similar to the one fixed by the previous commit easier to
detect.
Suggested-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/0A9A8DAC-BC3C-4C7A-9504-2C6050405544@anarazel.de
pgss_ProcessUtility() included a reference to a portion of a PlannedStmt
after the point where this data's structure could have been freed,
causing an incorrect memory access. There was a comment documenting
this requirement, missed in 3357471cf9.
This commit includes a test able to make valgrind complain with a
PlannedStmt freed by an internal ROLLBACK query. Similarly to what is
mentioned in 495e73c207, this can be triggered by using the extended
query protocol, something that can be now tested thanks to the recent
meta-command additions in psql. This commit mentions potential other
cases, but as far as I can see the extended protocol case with an
internal ROLLBACK is the only problematic pattern reachable in practice.
Issue introduced by 3357471cf9, gone unnoticed due to a lack of test
coverage. The fix is authored by Chao, my contribution being the new
test.
Author: Chao Li <li.evan.chao@gmail.com>
Co-authored-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/2F91906A-F2B5-4A6B-9695-D136957D4545@gmail.com
Until now extensions that wanted to measure overall query execution could
create QueryDesc->totaltime, which the core executor would then start and
stop. That's a bit odd and composes badly, e.g. extensions always had to use
INSTRUMENT_ALL, because otherwise another extension might not get what they
need.
Instead this introduces a new field, QueryDesc->query_instr_options, that
extensions can use to indicate whether they need query level instrumentation
populated, and with which instrumentation options. Extensions should take care
to only add options they need, instead of replacing the options of others.
The prior name of the field, totaltime, sounded like it would only measure
time, but these days the instrumentation infrastructure can track more
resources. The secondary benefit is that this will make it obvious to
extensions that they may not create the Instrumentation struct themselves
anymore (often extensions build only against a postgres build without
assertions).
Adjust pg_stat_statements and auto_explain to match, and lower the
requested instrumentation level for auto_explain to INSTRUMENT_TIMER,
since the summary instrumentation it needs is only runtime.
The reason to push this now, rather in the PG 20 cycle, is that 5a79e78501
already required extensions using query level instrumentations to adjust their
code, and it seemed undesirable to require them to do so again for 20.
Author: Lukas Fittl <lukas@fittl.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAP53Pkyqsht+exJQYRsjhSWYKu+vFGHhPub7m6PmFD6Or0=p1g@mail.gmail.com
This commit changes the post_parse_analyze_hook_type() hook to take a
const JumbleState, to tell external modules that they are not allowed to
touch the JumbleState that has been compiled by the core code. This
fixes a pretty old problem with pg_stat_statements, that had always the
idea of modifying the lengths of the constants stored in the
JumbleState. The previous state could confuse extensions that need to
look at a JumbleState depending on the loading order, if
pg_stat_statements is part of the stack loaded.
Another piece included in this commit is the move of the routine
fill_in_constant_lengths() to queryjumblefuncs.c, to give an option to
extensions to compile the lengths of the constants, if necessary. I was
surprised by the number of external code that carries a copy of this
routine (see the thread for details). Previously, this routine modified
JumbleState. It now copies the set of LocationLens from JumbleState,
and fills the constant lengths for separate use.
pg_stat_statements is updated to use the new ComputeConstantLengths().
JumbleState is now marked with a const in the module, where relevant.
Author: Sami Imseih <samimseih@gmail.com>
Co-authored-by: Lukas Fittl <lukas@fittl.com>
Discussion: https://postgr.es/m/CAA5RZ0tZp5qU0ikZEEqJnxvdSNGh1DWv80sb-k4QAUmiMoOp_Q@mail.gmail.com
As part of this, embed the LWLock it needs in the shared memory struct
itself, so that we don't need to use RequestNamedLWLockTranche()
anymore. LWLockNewTrancheId() + LWLockInitialize() is more convenient
to use in extensions.
Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://www.postgresql.org/message-id/CAExHW5vM1bneLYfg0wGeAa=52UiJ3z4vKd3AJ72X8Fw6k3KKrg@mail.gmail.com
Previously, different places (e.g. query "total time") were repurposing the
Instrumentation struct initially introduced for capturing per-node statistics
during execution. This overuse of the same struct is confusing, e.g. by
cluttering calls of InstrStartNode/InstrStopNode in unrelated code paths, and
prevents future refactorings.
Instead, simplify the Instrumentation struct to only track time and WAL/buffer
usage. Similarly, drop the use of InstrEndLoop outside of per-node
instrumentation - these calls were added without any apparent benefit since
the relevant fields were never read.
Introduce the NodeInstrumentation struct to carry forward the per-node
instrumentation information. WorkerInstrumentation is renamed to
WorkerNodeInstrumentation for clarity.
In passing, clarify that InstrAggNode is expected to only run after
InstrEndLoop (as it does in practice), and drop unused code.
This also fixes a consequence-less bug: Previously ->async_mode was only set
when a non-zero instrument_option was passed. That turns out to be harmless
right now, as ->async_mode only affects a timing related field.
Author: Lukas Fittl <lukas@fittl.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAP53PkzdBK8VJ1fS4AZ481LgMN8f9mJiC39ZRHqkFUSYq6KWmg@mail.gmail.com
Introduce TriggerInstrumentation to capture trigger timing and firings
(previously counted in "ntuples"), to aid a future refactoring that
splits out all Instrumentation fields beyond timing and WAL/buffers into
more specific structs.
In passing, drop the "n" argument to InstrAlloc, as all remaining callers need
exactly one Instrumentation struct. The duplication between InstrAlloc() and
InstrInit(), as well as the conditional initialization of async_mode will be
addressed in a subsequent commit.
Author: Lukas Fittl <lukas@fittl.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://www.postgresql.org/message-id/flat/CAP53PkzdBK8VJ1fS4AZ481LgMN8f9mJiC39ZRHqkFUSYq6KWmg@mail.gmail.com
Replace the separate init and max size options with a single size
option. We didn't make much use of the feature, all callers except the
ones in wait_event.c already used the same size for both, and the hash
tables in wait_event.c are small so there's little harm in just
allocating them to the max size.
The only reason why you might want to not reserve the max size upfront
is to make the memory available for other hash tables to grow beyond
their max size. Letting hash tables grow much beyond their max size is
bad for performance, however, because we cannot resize the directory,
and we never had very much "wiggle room" to grow to anyway so you
couldn't really rely on it. We recently marked the LOCK and PROCLOCK
tables with HAS_FIXED_SIZE, so there's nothing left in core that would
benefit from more unallocated shared memory.
Reviewed-by: Tomas Vondra <tomas@vondra.me>
Discussion: https://www.postgresql.org/message-id/01ab1d41-3eda-4705-8bbd-af898f5007f1@iki.fi
Previously, we always fed SELECT ... INTO to the SPI machinery.
While that works for all cases, it's a great deal slower than
the otherwise-equivalent "var := expression" if the expression
is "simple" and the INTO target is a single variable. Users
coming from MSSQL or T_SQL are likely to be surprised by this;
they are used to writing SELECT ... INTO since there is no
"var := expression" syntax in those dialects. Hence, check for
a simple expression and use the faster code path if possible.
(Here, "simple" means whatever exec_is_simple_query accepts,
which basically means "SELECT scalar-expression" without any
input tables, aggregates, qual clauses, etc.)
This optimization is not entirely transparent. Notably, one of
the reasons it's faster is that the hooks that pg_stat_statements
uses aren't called in this path, so that the evaluated expression
no longer appears in pg_stat_statements output as it did before.
There may be some other minor behavioral changes too, although
I tried hard to make error reporting look the same. Hopefully,
none of them are significant enough to not be acceptable as
routine changes in a PG major version.
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://postgr.es/m/CAFj8pRDieSQOPDHD_svvR75875uRejS9cN87FoAC3iXMXS1saQ@mail.gmail.com
Remove a bunch of #include lines from execnodes.h. Most of these
requier suitable typedefs to be added, so that it still compiles
standalone. In one case, the fix is to move a struct definition to the
one .c file where it is needed.
Also some light clean up in plannodes.h and genam.h, though not as
extensive as in execnodes.h.
Author: Álvaro Herrera <alvherre@kurilemu.de>
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/202603131240.ihwqdxnj7w2o@alvherre.pgsql
Builds with CLOBBER_CACHE_ALWAYS enabled are failing the new test
introduced in 1572ea96e6, checking the nesting level calculation in
the planner hook. The inner query of the function called twice is
registered as normalized, as such builds would register a PGSS entry in
the post-parse-analyse hook due to the cached plans requiring
revalidation.
A trick based on debug_discard_caches cannot work as far as I can, a
normalized query still being registered. This commit takes a different
approach with the addition of a DISCARD PLANS before the first function
call. This forces the use of a normalized query in the PGSS entry for
the inner query of the function with and without CLOBBER_CACHE_ALWAYS,
which should be enough to stabilize the test. Note that the test is
still checking what it should: when removing the nesting level
calculation in the planner hook of PGSS, one still gets a failure for
the PGSS entry of the inner query in the function, with "toplevel" being
flipped to true instead of false (it should be false, as a non-top-level
entry).
Per buildfarm members avocet and trilobite, at least.
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/82dd02bb-4e0f-40ad-a60b-baa1763ff0bd@gmail.com
Continuing to support this backwards-compatibility feature has
nontrivial costs; in particular it is potentially a security hazard
if an application somehow gets confused about which setting the
server is using. We changed the default to ON fifteen years ago,
which seems like enough time for applications to have adapted.
Let's remove support for the legacy string syntax.
We should not remove the GUC altogether, since client-side code will
still test it, pg_dump scripts will attempt to set it to ON, etc.
Instead, just prevent it from being set to OFF. There is precedent
for this approach (see commit de66987ad).
This patch does remove the related GUC escape_string_warning, however.
That setting does nothing when standard_conforming_strings is on,
so it's now useless. We could leave it in place as a do-nothing
setting to avoid breaking clients that still set it, if there are any.
But it seems likely that any such client is also trying to turn off
standard_conforming_strings, so it'll need work anyway.
The client-side changes in this patch are pretty minimal, because even
though we are dropping the server's support, most of our clients still
need to be able to talk to older server versions. We could remove
dead client code only once we disclaim compatibility with pre-v19
servers, which is surely years away. One change of note is that
pg_dump/pg_dumpall now set standard_conforming_strings = on in their
source session, rather than accepting the source server's default.
This ensures that literals in view definitions and such will be
printed in a way that's acceptable to v19+. In particular,
pg_upgrade will work transparently even if the source installation has
standard_conforming_strings = off. (However, pg_restore will behave
the same as before if given an archive file containing
standard_conforming_strings = off. Such an archive will not be safely
restorable into v19+, but we shouldn't break the ability to extract
valid data from it for use with an older server.)
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/3279216.1767072538@sss.pgh.pa.us
This commit adds tests to verify the computation of the nesting level
for two code paths: the planner hook and the ExecutorFinish() hook. The
nesting level is essential to save a correct "toplevel" status for the
added PGSS entries.
The author has noticed that removing the manipulations of nesting_level
in these two code paths did not cause the tests to complain, meaning
that we never had coverage for the assumptions taken by the code.
Author: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/CAA5RZ0uK1PSrgf52bWCtDpzaqbWt04o6ZA7zBm6UQyv7vyvf9w@mail.gmail.com
The test "squashing" was the last item of the REGRESS list, but
"cleanup" should be the second to last, dropping the extension.
"oldextversions" is the last item.
In passing, the REGRESS list is cleaned up to include one item per line,
so as diffs are minimized when adding new test files.
Noticed while playing with this area of the code.
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Man Zeng <zengman@halodbtech.com>
Discussion: https://postgr.es/m/aW6_Xc8auuu5iAPi@paquier.xyz
When IN/ANY clauses contain both constants and variable expressions, the
optimizer transforms them into separate structures: constants become
an array expression while variables become individual OR conditions.
This transformation was creating an overlap with the token locations,
causing pg_stat_statements query normalization to crash because it
could not calculate the amount of bytes remaining to write for the
normalized query.
This commit disables squashing for mixed IN list expressions when
constructing a scalar array op, by setting list_start and list_end
to -1 when both variables and non-variables are present. Some
regression tests are added to PGSS to verify these patterns.
Author: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Dmitry Dolgov <9erthalion6@gmail.com>
Discussion: https://postgr.es/m/CAA5RZ0ts9qiONnHjjHxPxtePs22GBo4d3jZ_s2BQC59AN7XbAA@mail.gmail.com
Backpatch-through: 18
RangeTblEntry.groupexprs was marked with the node attribute
query_jumble_ignore, causing a list of GROUP BY expressions to be
ignored during the query jumbling. For example, these two queries could
be grouped together within the same query ID:
SELECT count(*) FROM t GROUP BY a;
SELECT count(*) FROM t GROUP BY b;
However, as such queries use different GROUP BY clauses, they should be
split across multiple entries.
This fixes an oversight in 247dea89f7, that has introduced an RTE for
GROUP BY clauses. Query IDs are documented as being stable across minor
releases, but as this is a regression new to v18 and that we are still
early in its support cycle, a backpatch is exceptionally done as this
has broken a behavior that exists since query jumbling is supported in
core, since its introduction in pg_stat_statements.
The tests of pg_stat_statements are expanded to cover this area, with
patterns involving GROUP BY and GROUPING clauses.
Author: Jian He <jian.universality@gmail.com>
Discussion: https://postgr.es/m/CACJufxEy2W+tCqC7XuJ94r3ivWsM=onKJp94kRFx3hoARjBeFQ@mail.gmail.com
Backpatch-through: 18
Previously the instrumentation logic always converted to seconds, only for
many of the callers to do unnecessary division to get to milliseconds. As an
upcoming refactoring will split the Instrumentation struct, utilize instrtime
always to keep things simpler. It's also a bit faster to not have to first
convert to a double in functions like InstrEndLoop(), InstrAggNode().
Author: Lukas Fittl <lukas@fittl.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAP53PkzZ3UotnRrrnXWAv=F4avRq9MQ8zU+bxoN9tpovEu6fGQ@mail.gmail.com
Two or more constants can have the same location. We handled this
correctly for non squashed constants, but failed to do it if squashed
(resulting in out-of-bounds memory access), because the code structure
became broken by commit 0f65f3eec4: we failed to update 'last_loc'
correctly when skipping these squashed constants.
The simplest fix seems to be to get rid of 'last_loc' altogether -- in
hindsight, it's quite pointless. Also, when ignoring a constant because
of this, make sure to fulfill fill_in_constant_lengths's duty of setting
its length to -1.
Lastly, we can use == instead of <= because the locations have been
sorted beforehand, so the < case cannot arise.
Co-authored-by: Sami Imseih <samimseih@gmail.com>
Co-authored-by: Dmitry Dolgov <9erthalion6@gmail.com>
Reported-by: Konstantin Knizhnik <knizhnik@garret.ru>
Backpatch-through: 18
Discussion: https://www.postgresql.org/message-id/2b91e358-0d99-43f7-be44-d2d4dbce37b3%40garret.ru
This allows extensions to have access to any data they've stored
in the ExplainState during planning. Unfortunately, it won't help
with EXPLAIN EXECUTE is used, but since that case is less common,
this still seems like an improvement.
Since planner() has quite a few arguments now, also add some
documentation of those arguments and the return value.
Author: Robert Haas <rhaas@postgresql.org>
Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Andrei Lepikhov <lepihov@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: http://postgr.es/m/CA+TgmoYWKHU2hKr62Toyzh-kTDEnMDeLw7gkOOnjL-TnOUq0kQ@mail.gmail.com
This code was relying on "long", which is signed 8 bytes everywhere
except on Windows where it is 4 bytes, that could potentially expose it
to overflows, even if the current uses in the code are fine as far as I
know. This code is now able to rely on the same sizeof() variable
everywhere, with int64. long was used for sizes, partition counts and
entry counts.
Some callers of the dynahash.c routines used long declarations, that can
be cleaned up to use int64 instead. There was one shortcut based on
SIZEOF_LONG, that can be removed. long is entirely removed from
dynahash.c and hsearch.h.
Similar work was done in b1e5c9fa9a.
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/aKQYp-bKTRtRauZ6@paquier.xyz
This patch adds two new counters to pg_stat_statements:
- generic_plan_calls
- custom_plan_calls
These counters track how many times a prepared statement was executed
using a generic or custom plan, respectively, providing a global
equivalent at query level, for top and non-top levels, of
pg_prepared_statements whose data is restricted to a single session.
This commit builds upon e125e36002. The module is bumped to version
1.13. PGSS_FILE_HEADER is bumped as well, something that the latest
patches touching the on-disk format of the PGSS file did not actually
bother with since 2022..
Author: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Ilia Evdokimov <ilya.evdokimov@tantorlabs.com>
Reviewed-by: Andrei Lepikhov <lepihov@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Nikolay Samokhvalov <nik@postgres.ai>
Discussion: https://postgr.es/m/CAA5RZ0uFw8Y9GCFvafhC=OA8NnMqVZyzXPfv_EePOt+iv1T-qQ@mail.gmail.com
Prior to this patch, every FETCH call would generate a unique queryId
with a different size specified. Depending on the workloads, this could
lead to a significant bloat in pg_stat_statements, as repeatedly calling
a specific cursor would result in a new queryId each time. For example,
FETCH 1 c1; and FETCH 2 c1; would produce different queryIds.
This patch improves the situation by normalizing the fetch size, so as
semantically similar statements generate the same queryId. As a result,
statements like the below, which differ syntactically but have the same
effect, will now share a single queryId:
FETCH FROM c1
FETCH NEXT c1
FETCH 1 c1
In order to do a normalization based on the keyword used in FETCH,
FetchStmt is tweaked with a new FetchDirectionKeywords. This matters
for "howMany", which could be set to a negative value depending on the
direction, and we want to normalize the queries with enough information
about the direction keywords provided, including RELATIVE, ABSOLUTE or
all the ALL variants.
Author: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/CAA5RZ0tA6LbHCg2qSS+KuM850BZC_+ZgHV7Ug6BXw22TNyF+MA@mail.gmail.com
Commit 62d712ecfd made query jumbling squash lists of Consts as a
single element, but there's no reason not to treat PARAM_EXTERN
parameters the same. For these purposes, these values are indeed
constants for any particular execution of a query.
In particular, this should make list squashing more useful for
applications using extended query protocol, which would use parameters
extensively.
A complication arises: if a query has both external parameters and
squashable lists, then the parameter number used as placeholder for the
squashed list might be inconsistent with regards to the parameter
numbers used by the query literal. To reduce the surprise factor, all
parameters are renumbered starting from 1 in that case.
Author: Sami Imseih <samimseih@gmail.com>
Author: Dmitry Dolgov <9erthalion6@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAA5RZ0tRXoPG2y6bMgBCWNDt0Tn=unRerbzYM=oW0syi1=C1OA@mail.gmail.com
There's no principled reason for query jumbling to only remove the first
layer of RelabelType and CoerceViaIO. Change it to see through as many
layers as there are.
The algorithm to squash lists of constants added by commit 62d712ecfd
was a bit too simplistic; we wanted to avoid adding unnecessary
complexity, but cases like direct function calls of typecasting
functions (and others) were missed, and bogus SQL syntax was being shown
in pg_stat_statements normalized query text field. To fix normalization
for those cases, we need the parser to transmit information about were
each list of constant values starts and ends, so add that to a couple of
nodes. Also add a few more test cases to make sure we're doing the
right thing.
The patch initially submitted by Sami added a new private struct in
gram.y to carry the start/end information for A_Expr, but I (Álvaro)
decided that a better fix was to remove the parser indirection via the
in_expr production, and instead create separate components in the a_expr
rule. I'm surprised that this works and doesn't require more changes,
but I assume (without checking) that the grammar used to be more complex
and got simplified at some point.
Bump catversion.
Author: Sami Imseih <samimseih@gmail.com>
Author: Dmitry Dolgov <9erthalion6@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAA5RZ0tRXoPG2y6bMgBCWNDt0Tn=unRerbzYM=oW0syi1=C1OA@mail.gmail.com
This commit reverts the two following commits:
- 499edb0974, track more precisely query locations for nested
statements.
- 06450c7b8c, a follow-up fix of 499edb0974 with query locations.
The test introduced in this commit is not reverted. This is proving
useful to track a problem that only pgaudit was able to detect.
These prove to have issues with the tracking of SELECT statements, when
these use multiple parenthesis which is something supported by the
grammar. Incorrect location and lengths are causing pg_stat_statements
to become confused, failing its job in query normalization with
potential out-of-bound writes because the location and the length may
not match with what can be handled. A lot of the query patterns
discussed when this issue was reported have no test coverage in the main
regression test suite, or the recovery test 027_stream_regress.pl would
have caught the problems as pg_stat_statements is loaded by the node
running the regression tests. A first step would be to improve the test
coverage to stress more the query normalization logic.
A different portion of this work was done in 45e0ba30fc, with the
addition of tests for nested queries. These can be left in the tree.
They are useful to track the way inner queries are currently tracked by
PGSS with non-top-level entries, and will be useful when reconsidering
in the future the work reverted here.
Reported-by: Alexander Kozhemyakin <a.kozhemyakin@postgrespro.ru>
Discussion: https://postgr.es/m/18947-cdd2668beffe02bf@postgresql.org
uint64 was perhaps chosen in cff440d36 as the type was uint32 prior to
that widening work.
Having this as uint64 doesn't make much sense and just adds the overhead of
having to remember that we always output this in its signed form. Let's
remove that overhead.
The signed form output is seemingly required since we have no way to
represent the full range of uint64 in an SQL type. We use BIGINT in places
like pg_stat_statements, which maps directly to int64.
The release notes "Source Code" section may want to mention this
adjustment as some extensions may wish to adjust their code.
Author: David Rowley <dgrowleyml@gmail.com>
Suggested-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/50cb0c8b-994b-48f9-a1c4-13039eb3536b@eisentraut.org
pg_stat_statements anticipates that certain constant locations may be
recorded multiple times and attempts to avoid calculating a length for
these locations in fill_in_constant_lengths().
However, during generate_normalized_query() where normalized query
strings are generated, these locations are not excluded from
consideration. This could increment the parameter number counter for
every recorded occurrence at such a location, leading to an incorrect
normalization in certain cases with gaps in the numbers reported.
For example, take this query:
SELECT WHERE '1' IN ('2'::int, '3'::int::text)
Before this commit, it would be normalized like that, with gaps in the
parameter numbers:
SELECT WHERE $1 IN ($3::int, $4::int::text)
However the correct, less confusing one should be like that:
SELECT WHERE $1 IN ($2::int, $3::int::text)
This commit fixes the computation of the parameter numbers to track the
number of constants replaced with an $n by a separate counter instead of
the iterator used to loop through the list of locations.
The underlying query IDs are not changed, neither are the normalized
strings for existing PGSS hash entries. New entries with fresh
normalized queries would automatically get reshaped based on the new
parameter numbering.
Issue discovered while discussing a separate problem for HEAD, but this
affects all the stable branches.
Author: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/CAA5RZ0tzxvWXsacGyxrixdhy3tTTDfJQqxyFBRFh31nNHBQ5qA@mail.gmail.com
Backpatch-through: 13
As pointed out by Tom Lane, the patch introduced fragile and invasive
design around plan invalidation handling when locking of prunable
partitions was deferred from plancache.c to the executor. In
particular, it violated assumptions about CachedPlan immutability and
altered executor APIs in ways that are difficult to justify given the
added complexity and overhead.
This also removes the firstResultRels field added to PlannedStmt in
commit 28317de72, which was intended to support deferred locking of
certain ModifyTable result relations.
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/605328.1747710381@sss.pgh.pa.us
The statement location calculated for some nested query cases was wrong
when multiple queries are sent as a single string, these being separated
by semicolons. As pointed by Sami Imseih, the location calculation was
incorrect when the last query of nested statement with multiple queries
does **NOT** finish with a semicolon for the last statement. In this
case, the statement length tracked by RawStmt is 0, which is equivalent
to say that the string should be used until its end. The code
previously discarded this case entirely, causing the location to remain
at 0, the same as pointing at the beginning of the string. This caused
pg_stat_statements to store incorrect query strings.
This issue has been introduced in 499edb0974. I have looked at the
diffs generated by pgaudit back then, and noticed the difference
generated for this nested query case, but I have missed the point that
it was an actual regression with an existing case. A test case is added
in pg_stat_statements to provide some coverage, restoring the pre-17
behavior for the calculation of the query locations. Special thanks to
David Steele, who, through an analysis of the test diffs generated by
pgaudit with the new v18 logic, has poked me about the fact that my
original analysis of the matter was wrong.
The test output of pg_overexplain is updated to reflect the new logic,
as the new locations refer to the beginning of the argument passed to
the function explain_filter(). When the module was introduced in
8d5ceb113e, which was after 499edb0974 (for the new calculation
method), the locations of the test were not actually right: the plan
generated for the query string given in input of the function pointed to
the top-level query, not the nested one.
Reported-by: David Steele <david@pgbackrest.org>
Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Reviewed-by: Jian He <jian.universality@gmail.com>
Reviewed-by: Sami Imseih <samimseih@gmail.com>
Reviewed-by: David Steele <david@pgbackrest.org>
Discussion: https://postgr.es/m/844a3b38-bbf1-4fb2-9fd6-f58c35c09917@pgbackrest.org
Commit 62d712ecfd introduced the capability to calculate the same
queryId for queries with different lengths of constants in a list for an
IN clause. This behavior was originally enabled with a GUC
query_id_squash_values. After a discussion about the value of such a
GUC, it was decided to back out of the use of a GUC and make the
squashing behavior the only available option.
Author: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/Z-LZyygkkNyA8-kR@msg.df7cb.de
Discussion: https://postgr.es/m/CA+q6zcVTK-3C-8NWV1oY2NZrvtnMCDqnyYYyk1T7WMUG65MeOQ@mail.gmail.com
Previously NULL nodes were ignored. This could cause issues where the
computed query ID could match for queries where fields that are next to
each other in their Node struct where one field was NULL and the other
non-NULL. For example, the Query struct had distinctClause and sortClause
next to each other. If someone wrote;
SELECT DISTINCT c1 FROM t;
and then;
SELECT c1 FROM t ORDER BY c1;
these would produce the same query ID since, in the first query, we
ignored the NULL sortClause and appended the jumble bytes for the
distictClause. In the latter query, since we did nothing for the NULL
distinctClause then jumble the non-NULL sortClause, and since the node
representation stored is the same in both cases, the query IDs were
identical.
Here we fix this by always accounting for NULL nodes by recording that
we saw a NULL in the jumble buffer. This fixes the issue as the order that
the NULL is recorded isn't the same in the above two queries.
Author: Bykov Ivan <i.bykov@modernsys.ru>
Author: Michael Paquier <michael@paquier.xyz>
Author: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/aafce7966e234372b2ba876c0193f1e9%40localhost.localdomain
It seems potentially useful to label our shared libraries with version
information, now that a facility exists for retrieving that. This
patch labels them with the PG_VERSION string. There was some
discussion about using semantic versioning conventions, but that
doesn't seem terribly helpful for modules with no SQL-level presence;
and for those that do have SQL objects, we typically expect them
to support multiple revisions of the SQL definitions, so it'd still
not be very helpful.
I did not label any of src/test/modules/. It seems unnecessary since
we don't install those, and besides there ought to be someplace that
still provides test coverage for the original PG_MODULE_MAGIC macro.
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/dd4d1b59-d0fe-49d5-b28f-1e463b68fa32@gmail.com
custom_query_jumble (introduced in 5ac462e2b7 as a node field
attribute) is now assigned to the expanded reference name "eref" of
RangeTblEntry, adding in the query jumble computation the non-qualified
aliased relation name, without the list of column names. The relation
OID is removed from the query jumbling.
The effects of this change can be seen in the tests added by
3430215fe3, where pg_stat_statements (PGSS) entries are now grouped
using the relation name, ignoring the relation search_path may point at.
For example, these two relations are different, but are now grouped in a
single PGSS entry as they are assigned the same query ID:
CREATE TABLE foo1.tab (a int);
CREATE TABLE foo2.tab (b int);
SET search_path = 'foo1';
SELECT count(*) FROM tab;
SET search_path = 'foo2';
SELECT count(*) FROM tab;
SELECT count(*) FROM foo1.tab;
SELECT count(*) FROM foo2.tab;
SELECT query, calls FROM pg_stat_statements WHERE query ~ 'FROM tab';
query | calls
--------------------------+-------
SELECT count(*) FROM tab | 4
(1 row)
It is still possible to use an alias in the FROM clause to split these.
This behavior is useful for relations re-created with the same name,
where queries based on such relations would be grouped in the same
PGSS entry. For permanent schemas, it should not really matter in
practice. The main benefit is for workloads that use a lot of temporary
relations, which are usually re-created with the same name continuously.
These can be a heavy source of bloat in PGSS depending on the workload.
Such entries can now be grouped together, improving the user experience.
The original idea from Christoph Berg used catalog lookups to find
temporary relations, something that the query jumble has never done, and
it could cause some performance regressions. The idea to use
RangeTblEntry.eref and the relation name, applying the same rules for
all relations, temporary and not temporary, has been proposed by Tom
Lane. The documentation additions have been suggested by Sami Imseih.
Author: Michael Paquier <michael@paquier.xyz>
Co-authored-by: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Christoph Berg <myon@debian.org>
Reviewed-by: Lukas Fittl <lukas@fittl.com>
Reviewed-by: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/Z9iWXKGwkm8RAC93@msg.df7cb.de
These tests provide coverage for RangeTblEntry and how query jumbling
works with search_path, as well as the case where relations are
re-created, generating a different query ID as the relation OID is used
in the computation.
A patch is under discussion to switch to a different approach based on
the relation name, and there was no test coverage for this area,
including how queries are currently grouped with search_path. This is
useful to track how the situation changes between HEAD and any patches
proposed.
Christoph has proposed the test with ON COMMIT DROP temporary tables,
and I have written the second part.
Author: Christoph Berg <myon@debian.org>
Author: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/Z9iWXKGwkm8RAC93@msg.df7cb.de
pg_stat_statements produces multiple entries for queries like
SELECT something FROM table WHERE col IN (1, 2, 3, ...)
depending on the number of parameters, because every element of
ArrayExpr is individually jumbled. Most of the time that's undesirable,
especially if the list becomes too large.
Fix this by introducing a new GUC query_id_squash_values which modifies
the node jumbling code to only consider the first and last element of a
list of constants, rather than each list element individually. This
affects both the query_id generated by query jumbling, as well as
pg_stat_statements query normalization so that it suppresses printing of
the individual elements of such a list.
The default value is off, meaning the previous behavior is maintained.
Author: Dmitry Dolgov <9erthalion6@gmail.com>
Reviewed-by: Sergey Dudoladov (mysterious, off-list)
Reviewed-by: David Geier <geidav.pg@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Sutou Kouhei <kou@clear-code.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Marcos Pegoraro <marcos@f10.com.br>
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Zhihong Yu <zyu@yugabyte.com>
Tested-by: Yasuo Honda <yasuo.honda@gmail.com>
Tested-by: Sergei Kornilov <sk@zsrv.org>
Tested-by: Maciek Sakrejda <m.sakrejda@gmail.com>
Tested-by: Chengxi Sun <sunchengxi@highgo.com>
Tested-by: Jakub Wartak <jakub.wartak@enterprisedb.com>
Discussion: https://postgr.es/m/CA+q6zcWtUbT_Sxj0V6HY6EZ89uv5wuG5aefpe_9n0Jr3VwntFg@mail.gmail.com
Commit ddb17e387a attempted to avoid
confusing users by displaying digits after the decimal point only when
nloops > 1, since it's impossible to have a fraction row count after a
single iteration. However, this made the regression tests unstable since
parallal queries will have nloops>1 for all nodes below the Gather or
Gather Merge in normal cases, but if the workers don't start in time and
the leader finishes all the work, they will suddenly have nloops==1,
making it unpredictable whether the digits after the decimal point would
be displayed or not. Although 44cbba9a7f
seemed to fix the immediate failures, it may still be the case that there
are lower-probability failures elsewhere in the regression tests.
Various fixes are possible here. For example, it has previously been
proposed that we should try to display the digits after the decimal
point only if rows/nloops is an integer, but currently rows is storead
as a float so it's not theoretically an exact quantity -- precision
could be lost in extreme cases. It has also been proposed that we
should try to display the digits after the decimal point only if we're
under some sort of construct that could potentially cause looping
regardless of whether it actually does. While such ideas are not
without merit, this patch adopts the much simpler solution of always
display two decimal digits. If that approach stands up to scrutiny
from the buildfarm and human users, it spares us the trouble of doing
anything more complex; if not, we can reassess.
This commit incidentally reverts 44cbba9a7f,
which should no longer be needed.
Author: Robert Haas <robertmhaas@gmail.com>
Author: Ilia Evdokimov <ilya.evdokimov@tantorlabs.com>
Discussion: http://postgr.es/m/CA+TgmoazzVHn8sFOMFAEwoqBTDxKT45D7mvkyeHgqtoD2cn58Q@mail.gmail.com
Before executing a cached generic plan, AcquireExecutorLocks() in
plancache.c locks all relations in a plan's range table to ensure the
plan is safe for execution. However, this locks runtime-prunable
relations that will later be pruned during "initial" runtime pruning,
introducing unnecessary overhead.
This commit defers locking for such relations to executor startup and
ensures that if the CachedPlan is invalidated due to concurrent DDL
during this window, replanning is triggered. Deferring these locks
avoids unnecessary locking overhead for pruned partitions, resulting
in significant speedup, particularly when many partitions are pruned
during initial runtime pruning.
* Changes to locking when executing generic plans:
AcquireExecutorLocks() now locks only unprunable relations, that is,
those found in PlannedStmt.unprunableRelids (introduced in commit
cbc127917e), to avoid locking runtime-prunable partitions
unnecessarily. The remaining locks are taken by
ExecDoInitialPruning(), which acquires them only for partitions that
survive pruning.
This deferral does not affect the locks required for permission
checking in InitPlan(), which takes place before initial pruning.
ExecCheckPermissions() now includes an Assert to verify that all
relations undergoing permission checks, none of which can be in the
set of runtime-prunable relations, are properly locked.
* Plan invalidation handling:
Deferring locks introduces a window where prunable relations may be
altered by concurrent DDL, invalidating the plan. A new function,
ExecutorStartCachedPlan(), wraps ExecutorStart() to detect and handle
invalidation caused by deferred locking. If invalidation occurs,
ExecutorStartCachedPlan() updates CachedPlan using the new
UpdateCachedPlan() function and retries execution with the updated
plan. To ensure all code paths that may be affected by this handle
invalidation properly, all callers of ExecutorStart that may execute a
PlannedStmt from a CachedPlan have been updated to use
ExecutorStartCachedPlan() instead.
UpdateCachedPlan() replaces stale plans in CachedPlan.stmt_list. A new
CachedPlan.stmt_context, created as a child of CachedPlan.context,
allows freeing old PlannedStmts while preserving the CachedPlan
structure and its statement list. This ensures that loops over
statements in upstream callers of ExecutorStartCachedPlan() remain
intact.
ExecutorStart() and ExecutorStart_hook implementations now return a
boolean value indicating whether plan initialization succeeded with a
valid PlanState tree in QueryDesc.planstate, or false otherwise, in
which case QueryDesc.planstate is NULL. Hook implementations are
required to call standard_ExecutorStart() at the beginning, and if it
returns false, they should do the same without proceeding.
* Testing:
To verify these changes, the delay_execution module tests scenarios
where cached plans become invalid due to changes in prunable relations
after deferred locks.
* Note to extension authors:
ExecutorStart_hook implementations must verify plan validity after
calling standard_ExecutorStart(), as explained earlier. For example:
if (prev_ExecutorStart)
plan_valid = prev_ExecutorStart(queryDesc, eflags);
else
plan_valid = standard_ExecutorStart(queryDesc, eflags);
if (!plan_valid)
return false;
<extension-code>
return true;
Extensions accessing child relations, especially prunable partitions,
via ExecGetRangeTableRelation() must now ensure their RT indexes are
present in es_unpruned_relids (introduced in commit cbc127917e), or
they will encounter an error. This is a strict requirement after this
change, as only relations in that set are locked.
The idea of deferring some locks to executor startup, allowing locks
for prunable partitions to be skipped, was first proposed by Tom Lane.
Reviewed-by: Robert Haas <robertmhaas@gmail.com> (earlier versions)
Reviewed-by: David Rowley <dgrowleyml@gmail.com> (earlier versions)
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (earlier versions)
Reviewed-by: Tomas Vondra <tomas@vondra.me>
Reviewed-by: Junwang Zhao <zhjwpku@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqFGkMSge6TgC9KQzde0ohpAycLQuV7ooitEEpbKB0O_mg@mail.gmail.com
wal_buffers_full tracks the number of times WAL buffers become full,
giving hints to be able to tune the GUC wal_buffers.
Up to now, this information was only available in pg_stat_wal. With
this field available in WalUsage since eaf502747b, exposing it in
pg_stat_statements is straight-forward, and it offers more granularity
at query level.
pg_stat_statements does not need a version bump as one has been done in
commit cf54a2c002 for this development cycle.
Author: Bertrand Drouvot
Reviewed-by: Ilia Evdokimov
Discussion: https://postgr.es/m/Z6SOha5YFFgvpwQY@ip-10-97-1-34.eu-west-3.compute.internal
Library unloading has never been supported with its code removed in
ab02d702ef, and there were some comments still mentioning that it was
a possible operation.
ChangAo has noticed the incorrect references in dfmgr.c, while I have
noticed the other ones while scanning the rest of the tree for similar
mistakes.
Author: ChangAo Chen, Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/tencent_1D09840A1632D406A610C8C4E2491D74DB0A@qq.com
Our parallel-mode code only works when we are executing a query
in full, so ExecutePlan must disable parallel mode when it is
asked to do partial execution. The previous logic for this
involved passing down a flag (variously named execute_once or
run_once) from callers of ExecutorRun or PortalRun. This is
overcomplicated, and unsurprisingly some of the callers didn't
get it right, since it requires keeping state that not all of
them have handy; not to mention that the requirements for it were
undocumented. That led to assertion failures in some corner
cases. The only state we really need for this is the existing
QueryDesc.already_executed flag, so let's just put all the
responsibility in ExecutePlan. (It could have been done in
ExecutorRun too, leading to a slightly shorter patch -- but if
there's ever more than one caller of ExecutePlan, it seems better
to have this logic in the subroutine than the callers.)
This makes those ExecutorRun/PortalRun parameters unnecessary.
In master it seems okay to just remove them, returning the
API for those functions to what it was before parallelism.
Such an API break is clearly not okay in stable branches,
but for them we can just leave the parameters in place after
documenting that they do nothing.
Per report from Yugo Nagata, who also reviewed and tested
this patch. Back-patch to all supported branches.
Discussion: https://postgr.es/m/20241206062549.710dc01cf91224809dd6c0e1@sraoss.co.jp
