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postgres_fdw tries to use PG_TRY blocks to ensure that it will
eventually free the PGresult created by the remote modify command.
However, it's fundamentally impossible for this scheme to work
reliably when there's RETURNING data, because the query could fail
in between invocations of postgres_fdw's DirectModify methods.
There is at least one instance of exactly this situation in the
regression tests, and the ensuing session-lifespan leak is visible
under Valgrind.
We can improve matters by using a memory context reset callback
attached to the ExecutorState context. That ensures that the
PGresult will be freed when the ExecutorState context is torn
down, even if control never reaches postgresEndDirectModify.
I have little faith that there aren't other potential PGresult
leakages in the backend modules that use libpq. So I think it'd
be a good idea to apply this concept universally by creating
infrastructure that attaches a reset callback to every PGresult
generated in the backend. However, that seems too invasive for
v18 at this point, let alone the back branches. So for the
moment, apply this narrow fix that just makes DirectModify safe.
I have a patch in the queue for the more general idea, but it
will have to wait for v19.
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Matheus Alcantara <matheusssilv97@gmail.com>
Discussion: https://postgr.es/m/2976982.1748049023@sss.pgh.pa.us
Backpatch-through: 13
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If a column is omitted in an INSERT, and there's no column default,
the code in preptlist.c generates a NULL Const to be inserted.
Furthermore, if the column is of a domain type, we wrap the Const
in CoerceToDomain, so as to throw a run-time error if the domain
has a NOT NULL constraint. That's fine as far as it goes, but
there are two problems:
1. We're being sloppy about the type/typmod that the Const is
labeled with. It really should have the domain's base type/typmod,
since it's the input to CoerceToDomain not the output. This can
result in coerce_to_domain inserting a useless length-coercion
function (useless because it's being applied to a null). The
coercion would typically get const-folded away later, but it'd
be better not to create it in the first place.
2. We're not applying expression preprocessing (specifically,
eval_const_expressions) to the resulting expression tree.
The planner's primary expression-preprocessing pass already happened,
so that means the length coercion step and CoerceToDomain node miss
preprocessing altogether.
This is at the least inefficient, since it means the length coercion
and CoerceToDomain will actually be executed for each inserted row,
though they could be const-folded away in most cases. Worse, it
seems possible that missing preprocessing for the length coercion
could result in an invalid plan (for example, due to failing to
perform default-function-argument insertion). I'm not aware of
any live bug of that sort with core datatypes, and it might be
unreachable for extension types as well because of restrictions of
CREATE CAST, but I'm not entirely convinced that it's unreachable.
Hence, it seems worth back-patching the fix (although I only went
back to v14, as the patch doesn't apply cleanly at all in v13).
There are several places in the rewriter that are building null
domain constants the same way as preptlist.c. While those are
before the planner and hence don't have any reachable bug, they're
still applying a length coercion that will be const-folded away
later, uselessly wasting cycles. Hence, make a utility routine
that all of these places can call to do it right.
Making this code more careful about the typmod assigned to the
generated NULL constant has visible but cosmetic effects on some
of the plans shown in contrib/postgres_fdw's regression tests.
Discussion: https://postgr.es/m/1865579.1738113656@sss.pgh.pa.us
Backpatch-through: 14
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Several places treat MyStartTime as a "long", which is only 32 bits
wide on some platforms. In reality, MyStartTime is a pg_time_t,
i.e., a signed 64-bit integer. This will lead to interesting bugs
on the aforementioned systems in 2038 when signed 32-bit integers
are no longer sufficient to store Unix time (e.g., "pg_ctl start"
hanging). To fix, ensure that MyStartTime is handled as a 64-bit
value everywhere. (Of course, users will need to ensure that
time_t is 64 bits wide on their system, too.)
Co-authored-by: Max Johnson
Discussion: https://postgr.es/m/CO1PR07MB905262E8AC270FAAACED66008D682%40CO1PR07MB9052.namprd07.prod.outlook.com
Backpatch-through: 12
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When pg_dump retrieves the list of database objects and performs the
data dump, there was possibility that objects are replaced with others
of the same name, such as views, and access them. This vulnerability
could result in code execution with superuser privileges during the
pg_dump process.
This issue can arise when dumping data of sequences, foreign
tables (only 13 or later), or tables registered with a WHERE clause in
the extension configuration table.
To address this, pg_dump now utilizes the newly introduced
restrict_nonsystem_relation_kind GUC parameter to restrict the
accesses to non-system views and foreign tables during the dump
process. This new GUC parameter is added to back branches too, but
these changes do not require cluster recreation.
Back-patch to all supported branches.
Reviewed-by: Noah Misch
Security: CVE-2024-7348
Backpatch-through: 12
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Commit d844cd75a disallowed rewind in a non-scrollable cursor to resolve
anomalies arising from such a cursor operation. However, this failed to
take into account the assumption in postgres_fdw that when rescanning a
foreign relation, it can rewind the cursor created for scanning the
foreign relation without specifying the SCROLL option, regardless of its
scrollability, causing this error when it tried to do such a rewind in a
non-scrollable cursor. Fix by modifying postgres_fdw to instead
recreate the cursor, regardless of its scrollability, when rescanning
the foreign relation. (If we had a way to check its scrollability, we
could improve this by rewinding it if it is scrollable and recreating it
if not, but we do not have it, so this commit modifies it to recreate it
in any case.)
Per bug #17889 from Eric Cyr. Devrim Gunduz also reported this problem.
Back-patch to v15 where that commit enforced the prohibition.
Reviewed by Tom Lane.
Discussion: https://postgr.es/m/17889-e8c39a251d258dda%40postgresql.org
Discussion: https://postgr.es/m/b415ac3255f8352d1ea921cf3b7ba39e0587768a.camel%40gunduz.org
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Previously, when considering LIMIT pushdown, postgres_fdw failed to
check whether the query has this clause, which led to pushing false
LIMIT clauses, causing incorrect results.
This clause has been supported since v13, so we need to do a
remote-version check before deciding that it will be safe to push such a
clause, but we do not currently have a way to do the check (without
accessing the remote server); disable pushing such a clause for now.
Oversight in commit 357889eb1. Back-patch to v13, where that commit
added the support.
Per bug #18467 from Onder Kalaci.
Patch by Japin Li, per a suggestion from Tom Lane, with some changes to
the comments by me. Review by Onder Kalaci, Alvaro Herrera, and me.
Discussion: https://postgr.es/m/18467-7bb89084ff03a08d%40postgresql.org
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This should have the same results for all practical purposes.
The advantage of selecting 'GMT' is that it's guaranteed to work
even when the remote system's timezone database is missing
entries, because pg_tzset() hard-wires handling of that,
at least in 9.2 and later.
(It seems like it would be a good idea to similarly hard-wire
correct handling of 'UTC', but that'll be a little more invasive
than I want to consider back-patching. Leave that for another
day when we're not in feature freeze.)
Per trouble report from Adnan Dautovic. Back-patch to all
supported branches.
Discussion: https://postgr.es/m/465248.1712211585@sss.pgh.pa.us
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No configured-by-FDW events would result in "return" directly out of a
PG_TRY block, making the exception stack dangling. Repair.
Oversight in commit 501cfd07d; back-patch to v14, like that commit, but
as we do not have this issue in HEAD (cf. commit 50c67c201), no need to
apply this patch to it.
In passing, improve a comment about the handling of in-process requests
in a postgres_fdw.c function called from this function.
Alexander Pyhalov, with comment adjustment/improvement by me.
Discussion: https://postgr.es/m/425fa29a429b21b0332737c42a4fdc70%40postgrespro.ru
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For UNION ALL queries where a union child query contained a foreign
table, if the targetlist of that query contained a constant, and the
top-level query performed an ORDER BY which contained the column for the
constant value, then postgres_fdw would find the EquivalenceMember with
the Const and then try to produce an ORDER BY containing that Const.
This caused problems with INT typed Consts as these could appear to be
requests to order by an ordinal column position rather than the constant
value. This could lead to either an error such as:
ERROR: ORDER BY position <int const> is not in select list
or worse, if the constant value is a valid column, then we could just
sort by the wrong column altogether.
Here we fix this issue by just not including these Consts in the ORDER
BY clause.
In passing, add a new section for testing ORDER BY in the postgres_fdw
tests and move two existing tests which were misplaced in the WHERE
clause testing section into it.
Reported-by: Michał Kłeczek
Reviewed-by: Ashutosh Bapat, Richard Guo
Bug: #18381
Discussion: https://postgr.es/m/0714C8B8-8D82-4ABB-9F8D-A0C3657E7B6E%40kleczek.org
Discussion: https://postgr.es/m/18381-137456acd168bf93%40postgresql.org
Backpatch-through: 12, oldest supported version
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If an error is thrown after calling CreateWaitEventSet(), the memory
of a WaitEventSet is free'd as it's allocated in the short-lived
memory context, but the file descriptor (on epoll- or kqueue-based
systems) or handles (on Windows) that it contains are leaked.
Use PG_TRY-FINALLY to ensure it gets freed. (On master, I will apply a
better fix, using ResourceOwners to track the WaitEventSet, but that's
not backpatchable.)
The added test doesn't check for leaking resources, so it passed even
before this commit. But at least it covers the code path.
In the passing, fix misleading comment on what the 'nevents' argument
to WaitEventSetWait means.
Report by Alexander Lakhin, analysis and suggestion for the fix by Tom
Lane. Fixes bug #17828. Backpatch to v14 where async execution was
introduced, but master gets a different fix.
Discussion: https://www.postgresql.org/message-id/17828-122da8cba23236be@postgresql.org
Discussion: https://www.postgresql.org/message-id/472235.1678387869@sss.pgh.pa.us
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Commit e4106b252 should have updated this test, but did not; back-patch
to all supported branches.
Reviewed by Richard Guo.
Discussion: http://postgr.es/m/CAPmGK15nR0NXLSCKQAcqbZbTzrzd5MozowWnTnGfPkayndF43Q%40mail.gmail.com
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Commit e7cb7ee14, which introduced the infrastructure for FDWs and
custom scan providers to replace joins with scans, failed to add support
handling of pseudoconstant quals assigned to replaced joins in
createplan.c, leading to an incorrect plan without a gating Result node
when postgres_fdw replaced a join with such a qual.
To fix, we could add the support by 1) modifying the ForeignPath and
CustomPath structs to store the list of RestrictInfo nodes to apply to
the join, as in JoinPaths, if they represent foreign and custom scans
replacing a join with a scan, and by 2) modifying create_scan_plan() in
createplan.c to use that list in that case, instead of the
baserestrictinfo list, to get pseudoconstant quals assigned to the join;
but #1 would cause an ABI break. So fix by modifying the infrastructure
to just disallow replacing joins with such quals.
Back-patch to all supported branches.
Reported by Nishant Sharma. Patch by me, reviewed by Nishant Sharma and
Richard Guo.
Discussion: https://postgr.es/m/CADrsxdbcN1vejBaf8a%2BQhrZY5PXL-04mCd4GDu6qm6FigDZd6Q%40mail.gmail.com
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The test inserted 70k rows into a foreign table, in order to verify
correct behavior with more than 65535 parameters, and was added in
response to a bug report.
However, this is rather expensive, especially when running the tests
under valgrind, CLOBBER_CACHE_ALWAYS etc. It doesn't seem worth it to
keep running the test, so remove it from all branches (14+).
Backpatch-through: 14
Discussion: https://postgr.es/m/2131017.1623451468@sss.pgh.pa.us
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The leak would show up when using batch inserts with foreign tables
included in a partition tree, as the slots used in the batch were not
reset once processed. In order to fix this problem, some
ExecClearTuple() are added to clean up the slots used once a batch is
filled and processed, mapping with the number of slots currently in use
as tracked by the counter ri_NumSlots.
This buffer refcount leak has been introduced in b676ac4 with the
addition of the executor facility to improve bulk inserts for FDWs, so
backpatch down to 14.
Alexander has provided the patch (slightly modified by me). The test
for postgres_fdw comes from me, based on the test case that the author
has sent in the report.
Author: Alexander Pyhalov
Discussion: https://postgr.es/m/b035780a740efd38dc30790c76927255@postgrespro.ru
Backpatch-through: 14
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The view just added by commit 53fe7e6cb decompiles differently
in v15 than HEAD (presumably as a consequence of 47bb9db75).
That causes failures in cross-version upgrade testing.
We could teach AdjustUpgrade.pm to compensate for that, but it
seems less painful to just drop the view after we're done with it.
Per buildfarm.
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postgres_fdw will close its remote session if an sinval cache reset
occurs, since it's possible that that means some FDW parameters
changed. We had two tests that were trying to ensure that the
session remains alive by setting debug_discard_caches = 0; but
that's not sufficient. Even though the tests seem stable enough
in the buildfarm, they flap a lot under CI.
In the first test, which is checking the ability to recover from
a lost connection, we can stabilize the results by just not
caring whether pg_terminate_backend() finds a victim backend.
If a reset did happen, there won't be a session to terminate
anymore, but the test can proceed anyway. (Arguably, we are
then not testing the unintentional-disconnect case, but as long
as that scenario is exercised in most runs I think it's fine;
testing the reset-driven case is of value too.)
In the second test, which is trying to verify the application_name
displayed in pg_stat_activity by a remote session, we had a race
condition in that the remote session might go away before we can
fetch its pg_stat_activity entry. We can close that race and make
the test more certainly test what it intends to by arranging things
so that the remote session itself fetches its pg_stat_activity entry
(based on PID rather than a somewhat-circular assumption about the
application name).
Both tests now demonstrably pass under debug_discard_caches = 1,
so we can remove that hack.
Back-patch into relevant back branches.
Discussion: https://postgr.es/m/20230226194340.u44bkfgyz64c67i6@awork3.anarazel.de
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postgres_fdw.application_name relies on MyProcPort to define the data
that should be added to escape sequences %u (user name) or %d (database
name). However this code could be run in processes that lack a
MyProcPort, like an autovacuum process, causing crashes.
The code generating the application name is made more flexible with this
commit, so as it now generates no data for %u and %d if MyProcPort is
missing, and a simple "unknown" if MyProcPort exists, but the expected
fields are not set.
Reported-by: Alexander Lakhin
Author: Kyotaro Horiguchi, Michael Paquier
Reviewed-by: Hayato Kuroda, Masahiko Sawada
Discussion: https://postgr.es/m/17789-8b31c5a4672b74d9@postgresql.org
Backpatch-through: 15
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We were identifying the updatable generated columns of inheritance
children by transposing the calculation made for their parent.
However, there's nothing that says a traditional-inheritance child
can't have generated columns that aren't there in its parent, or that
have different dependencies than are in the parent's expression.
(At present it seems that we don't enforce that for partitioning
either, which is likely wrong to some degree or other; but the case
clearly needs to be handled with traditional inheritance.)
Hence, drop the very-klugy-anyway "extraUpdatedCols" RTE field
in favor of identifying which generated columns depend on updated
columns during executor startup. In HEAD we can remove
extraUpdatedCols altogether; in back branches, it's still there but
always empty. Another difference between the HEAD and back-branch
versions of this patch is that in HEAD we can add the new bitmap field
to ResultRelInfo, but that would cause an ABI break in back branches.
Like 4b3e37993, add a List field at the end of struct EState instead.
Back-patch to v13. The bogus calculation is also being made in v12,
but it doesn't have the same visible effect because we don't use it
to decide which generated columns to recalculate; as a consequence of
which the patch doesn't apply easily. I think that there might still
be a demonstrable bug associated with trigger firing conditions, but
that's such a weird corner-case usage that I'm content to leave it
unfixed in v12.
Amit Langote and Tom Lane
Discussion: https://postgr.es/m/CA+HiwqFshLKNvQUd1DgwJ-7tsTp=dwv7KZqXC4j2wYBV1aCDUA@mail.gmail.com
Discussion: https://postgr.es/m/2793383.1672944799@sss.pgh.pa.us
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Commit b663a4136, which allowed FDWs to INSERT rows in bulk, added to
nodeModifyTable.c code to flush pending inserts to the foreign-table
result relation(s) before completing processing of the ModifyTable node,
but the code failed to take into account the case where the INSERT query
has modifying CTEs, leading to incorrect results.
Also, that commit failed to flush pending inserts before firing BEFORE
ROW triggers so that rows are visible to such triggers.
In that commit we scanned through EState's
es_tuple_routing_result_relations or es_opened_result_relations list to
find the foreign-table result relations to which pending inserts are
flushed, but that would be inefficient in some cases. So to fix, 1) add
a List member to EState to record the insert-pending result relations,
and 2) modify nodeModifyTable.c so that it adds the foreign-table result
relation to the list in ExecInsert() if appropriate, and flushes pending
inserts properly using the list where needed.
While here, fix a copy-and-pasteo in a comment in ExecBatchInsert(),
which was added by that commit.
Back-patch to v14 where that commit appeared.
Discussion: https://postgr.es/m/CAPmGK16qutyCmyJJzgQOhfBq%3DNoGDqTB6O0QBZTihrbqre%2BoxA%40mail.gmail.com
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Per discussion, the existing routine name able to initialize a SRF
function with materialize mode is unpopular, so rename it. Equally, the
flags of this function are renamed, as of:
- SRF_SINGLE_USE_EXPECTED -> MAT_SRF_USE_EXPECTED_DESC
- SRF_SINGLE_BLESS -> MAT_SRF_BLESS
The previous function and flags introduced in 9e98583 are kept around
for compatibility purposes, so as any extension code already compiled
with v15 continues to work as-is. The declarations introduced here for
compatibility will be removed from HEAD in a follow-up commit.
The new names have been suggested by Andres Freund and Melanie
Plageman.
Discussion: https://postgr.es/m/20221013194820.ciktb2sbbpw7cljm@awork3.anarazel.de
Backpatch-through: 15
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While directly targetting a foreign table with MERGE was already
expressly forbidden, we failed to catch the case of a partitioned table
that has a foreign table as a partition; and the result if you try is an
incomprehensible error. Fix that by adding a specific check.
Backpatch to 15.
Reported-by: Tatsuhiro Nakamori <bt22nakamorit@oss.nttdata.com>
Discussion: https://postgr.es/m/bt22nakamorit@oss.nttdata.com
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This reverts commit db0d67db2401eb6238ccc04c6407a4fd4f985832 and
several follow-on fixes. The idea of making a cost-based choice
of the order of the sorting columns is not fundamentally unsound,
but it requires cost information and data statistics that we don't
really have. For example, relying on procost to distinguish the
relative costs of different sort comparators is pretty pointless
so long as most such comparator functions are labeled with cost 1.0.
Moreover, estimating the number of comparisons done by Quicksort
requires more than just an estimate of the number of distinct values
in the input: you also need some idea of the sizes of the larger
groups, if you want an estimate that's good to better than a factor of
three or so. That's data that's often unknown or not very reliable.
Worse, to arrive at estimates of the number of calls made to the
lower-order-column comparison functions, the code needs to make
estimates of the numbers of distinct values of multiple columns,
which are necessarily even less trustworthy than per-column stats.
Even if all the inputs are perfectly reliable, the cost algorithm
as-implemented cannot offer useful information about how to order
sorting columns beyond the point at which the average group size
is estimated to drop to 1.
Close inspection of the code added by db0d67db2 shows that there
are also multiple small bugs. These could have been fixed, but
there's not much point if we don't trust the estimates to be
accurate in-principle.
Finally, the changes in cost_sort's behavior made for very large
changes (often a factor of 2 or so) in the cost estimates for all
sorting operations, not only those for multi-column GROUP BY.
That naturally changes plan choices in many situations, and there's
precious little evidence to show that the changes are for the better.
Given the above doubts about whether the new estimates are really
trustworthy, it's hard to summon much confidence that these changes
are better on the average.
Since we're hard up against the release deadline for v15, let's
revert these changes for now. We can always try again later.
Note: in v15, I left T_PathKeyInfo in place in nodes.h even though
it's unreferenced. Removing it would be an ABI break, and it seems
a bit late in the release cycle for that.
Discussion: https://postgr.es/m/TYAPR01MB586665EB5FB2C3807E893941F5579@TYAPR01MB5866.jpnprd01.prod.outlook.com
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The tlist of the EvalPlanQual outer plan for a ForeignScan node is
adjusted to produce a tuple whose descriptor matches the scan tuple slot
for the ForeignScan node. But in the case where the outer plan contains
an extra Sort node, if the new tlist contained columns required only for
evaluating PlaceHolderVars or columns required only for evaluating local
conditions, this would cause setrefs.c to fail with the error.
The cause of this is that when creating the outer plan by injecting the
Sort node into an alternative local join plan that could emit such extra
columns as well, we fail to arrange for the outer plan to propagate them
up through the Sort node, causing setrefs.c to fail to match up them in
the new tlist to what is available from the outer plan. Repair.
Per report from Alexander Pyhalov.
Richard Guo and Etsuro Fujita, reviewed by Alexander Pyhalov and Tom Lane.
Backpatch to all supported versions.
Discussion: http://postgr.es/m/cfb17bf6dfdf876467bd5ef533852d18%40postgrespro.ru
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When inserting a view referencing a foreign table that has WITH CHECK
OPTION constraints, in single-insert mode postgres_fdw retrieves the
data that was actually inserted on the remote side so that the WITH
CHECK OPTION constraints are enforced with the data locally, but in
batch-insert mode it cannot currently retrieve the data (except for the
row first inserted through the view), resulting in enforcing the WITH
CHECK OPTION constraints with the data passed from the core (except for
the first-inserted row), which led to incorrect results when inserting
into a view referencing a foreign table in which a remote BEFORE ROW
INSERT trigger changes the rows inserted through the view so that they
violate the view's WITH CHECK OPTION constraint. Also, the query
inserting into the view caused an assertion failure in assert-enabled
builds.
Fix these by disabling batch insertion when inserting into such a view.
Back-patch to v14 where batch insertion was added.
Discussion: https://postgr.es/m/CAPmGK17LpbTZs4m4a_6THP54UBeK9fHvX8aVVA%2BC6yEZDZwQcg%40mail.gmail.com
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When postgres_fdw begins an asynchronous data fetch, it submits FETCH query
by using PQsendQuery(). If PQsendQuery() fails and returns 0, postgres_fdw
should report an error. But, previously, postgres_fdw reported an error
only when the return value is less than 0, though PQsendQuery() never return
the values other than 0 and 1. Therefore postgres_fdw could not handle
the failure to send FETCH query in an asynchronous data fetch.
This commit fixes postgres_fdw so that it reports an error
when PQsendQuery() returns 0.
Back-patch to v14 where asynchronous execution was supported in postgres_fdw.
Author: Fujii Masao
Reviewed-by: Japin Li, Tom Lane
Discussion: https://postgr.es/m/b187a7cf-d4e3-5a32-4d01-8383677797f3@oss.nttdata.com
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Detail and hint messages should be full sentences and should end with a
period, but some of the messages newly-introduced in v15 did not follow
that.
Author: Justin Pryzby
Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/20220719120948.GF12702@telsasoft.com
Backpatch-through: 15
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The motivation for this is to ensure successful transmission of the
values of constants of regconfig and other reg* types. The remote
will be reading them with search_path = 'pg_catalog', so schema
qualification is necessary when referencing objects in other schemas.
Per bug #17483 from Emmanuel Quincerot. Back-patch to all supported
versions. (There's some other stuff to do here, but it's less
back-patchable.)
Discussion: https://postgr.es/m/1423433.1652722406@sss.pgh.pa.us
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Oversight in commit 4036bcbbb; back-patch to v15 where that appeared.
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Run pgindent, pgperltidy, and reformat-dat-files.
I manually fixed a couple of comments that pgindent uglified.
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Expand the comment about the parallel_commit option to mention that the
default is false.
Also, since the comment about alteration of the keep_connections option,
which was located above the expanded comment, holds true for the
parallel_commit option, rewrite it to reflect this, and move it to after
the expanded comment.
Follow-up for commit 04e706d42.
Discussion: https://postgr.es/m/CAPmGK16Kg2Bf90sqzcZ4YM5cN_G-4h7wFUS01qQpqNB%2B2BG5_w%40mail.gmail.com
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mark_async_capable_plan(), which is called from create_append_plan() to
determine whether subplans are async-capable, failed to take into
account that the given subplan created from a given subpath might
include a gating Result node if the subpath is a SubqueryScanPath or
ForeignPath, causing a segmentation fault there when the subplan created
from a SubqueryScanPath includes the Result node, or causing
ExecAsyncRequest() to throw an error about an unrecognized node type
when the subplan created from a ForeignPath includes the Result node,
because in the latter case the Result node was unintentionally
considered as async-capable, but we don't currently support executing
Result nodes asynchronously. Fix by modifying mark_async_capable_plan()
to disable asynchronous execution in such cases. Also, adjust code in
the ProjectionPath case in mark_async_capable_plan(), for consistency
with other cases, and adjust/improve comments there.
is_async_capable_path() added in commit 27e1f1456, which was rewritten
to mark_async_capable_plan() in a later commit, has the same issue,
causing the error at execution mentioned above, so back-patch to v14
where the aforesaid commit went in.
Per report from Justin Pryzby.
Etsuro Fujita, reviewed by Zhihong Yu and Justin Pryzby.
Discussion: https://postgr.es/m/20220408124338.GK24419%40telsasoft.com
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Previously, we allowed this, but such triggers might query the table to
insert into and act differently if the tuples that have already been
processed and prepared for insertion are not there, so disable it in
such cases.
Back-patch to v14 where batch insert was added.
Discussion: https://postgr.es/m/CAPmGK16_uPqsmgK0-LpLSUk54_BoK13bPrhxhfjSoSTVz414hA%40mail.gmail.com
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These are useless and distracting. We wouldn't have written the code
with them to begin with, so there's no reason to keep them.
Author: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20220411020336.GB26620@telsasoft.com
Discussion: https://postgr.es/m/attachment/133167/0016-Extraneous-blank-lines.patch
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In commit 27e1f1456, create_append_plan() only allowed the subplan
created from a given subpath to be executed asynchronously when it was
an async-capable ForeignPath. To extend coverage, this patch handles
cases when the given subpath includes some other Path types as well that
can be omitted in the plan processing, such as a ProjectionPath directly
atop an async-capable ForeignPath, allowing asynchronous execution in
partitioned-scan/partitioned-join queries with non-Var tlist expressions
and more UNION queries.
Andrey Lepikhov and Etsuro Fujita, reviewed by Alexander Pyhalov and
Zhihong Yu.
Discussion: https://postgr.es/m/659c37a8-3e71-0ff2-394c-f04428c76f08%40postgrespro.ru
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postgres_fdw would push ORDER BY clauses to the remote side without
verifying that the sort operator is safe to ship. Moreover, it failed
to print a suitable USING clause if the sort operator isn't default
for the sort expression's type. The net result of this is that the
remote sort might not have anywhere near the semantics we expect,
which'd be disastrous for locally-performed merge joins in particular.
We addressed similar issues in the context of ORDER BY within an
aggregate function call in commit 7012b132d, but failed to notice
that query-level ORDER BY was broken. Thus, much of the necessary
logic already existed, but it requires refactoring to be usable
in both cases.
Back-patch to all supported branches. In HEAD only, remove the
core code's copy of find_em_expr_for_rel, which is no longer used
and really should never have been pushed into equivclass.c in the
first place.
Ronan Dunklau, per report from David Rowley;
reviews by David Rowley, Ranier Vilela, and myself
Discussion: https://postgr.es/m/CAApHDvr4OeC2DBVY--zVP83-K=bYrTD7F8SZDhN4g+pj2f2S-A@mail.gmail.com
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When evaluating a query with a multi-column GROUP BY clause using sort,
the cost may be heavily dependent on the order in which the keys are
compared when building the groups. Grouping does not imply any ordering,
so we're allowed to compare the keys in arbitrary order, and a Hash Agg
leverages this. But for Group Agg, we simply compared keys in the order
as specified in the query. This commit explores alternative ordering of
the keys, trying to find a cheaper one.
In principle, we might generate grouping paths for all permutations of
the keys, and leave the rest to the optimizer. But that might get very
expensive, so we try to pick only a couple interesting orderings based
on both local and global information.
When planning the grouping path, we explore statistics (number of
distinct values, cost of the comparison function) for the keys and
reorder them to minimize comparison costs. Intuitively, it may be better
to perform more expensive comparisons (for complex data types etc.)
last, because maybe the cheaper comparisons will be enough. Similarly,
the higher the cardinality of a key, the lower the probability we’ll
need to compare more keys. The patch generates and costs various
orderings, picking the cheapest ones.
The ordering of group keys may interact with other parts of the query,
some of which may not be known while planning the grouping. E.g. there
may be an explicit ORDER BY clause, or some other ordering-dependent
operation, higher up in the query, and using the same ordering may allow
using either incremental sort or even eliminate the sort entirely.
The patch generates orderings and picks those minimizing the comparison
cost (for various pathkeys), and then adds orderings that might be
useful for operations higher up in the plan (ORDER BY, etc.). Finally,
it always keeps the ordering specified in the query, on the assumption
the user might have additional insights.
This introduces a new GUC enable_group_by_reordering, so that the
optimization may be disabled if needed.
The original patch was proposed by Teodor Sigaev, and later improved and
reworked by Dmitry Dolgov. Reviews by a number of people, including me,
Andrey Lepikhov, Claudio Freire, Ibrar Ahmed and Zhihong Yu.
Author: Dmitry Dolgov, Teodor Sigaev, Tomas Vondra
Reviewed-by: Tomas Vondra, Andrey Lepikhov, Claudio Freire, Ibrar Ahmed, Zhihong Yu
Discussion: https://postgr.es/m/7c79e6a5-8597-74e8-0671-1c39d124c9d6%40sigaev.ru
Discussion: https://postgr.es/m/CA%2Bq6zcW_4o2NC0zutLkOJPsFt80megSpX_dVRo6GK9PC-Jx_Ag%40mail.gmail.com
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Commit 85c696112 introduced this function to deduplicate code in the
transaction callback functions, but the SQL command passed as an
argument to it was useless when it returned before aborting a remote
transaction using the command. Modify pgfdw_abort_cleanup() so that it
constructs the command when/if necessary, as before, removing the
argument from it. Also update comments in pgfdw_abort_cleanup() and one
of the calling functions.
Etsuro Fujita, reviewed by David Zhang.
Discussion: https://postgr.es/m/CAPmGK158hrd%3DZfXmgkmNFHivgh18e4oE2Gz151C2Q4OBDjZ08A%40mail.gmail.com
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9e98583 introduced a helper to centralize building their needed state
(tuplestore, tuple descriptors, etc.), checking for any errors. This
commit updates all places of contrib/ that can be switched to use
SetSingleFuncCall() as a drop-in replacement, resulting in the removal
of a lot of boilerplate code in all the modules updated by this commit.
Per analysis, some places remain as they are:
- pg_logdir_ls() in adminpack/ uses historically TYPEFUNC_RECORD as
return type, and I suspect that changing it may cause issues at run-time
with some of its past versions, down to 1.0.
- dblink/ uses a wrapper function doing exactly the work of
SetSingleFuncCall(). Here the switch should be possible, but rather
invasive so it does not seem the extra backpatch maintenance cost.
- tablefunc/, similarly, uses multiple helper functions with portions of
SetSingleFuncCall() spread across the code paths of this module.
Author: Melanie Plageman
Discussion: https://postgr.es/m/CAAKRu_bvDPJoL9mH6eYwvBpPtTGQwbDzfJbCM-OjkSZDu5yTPg@mail.gmail.com
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postgres_fdw commits remote (sub)transactions opened on remote server(s)
in a local (sub)transaction one by one when the local (sub)transaction
commits. This patch allows it to commit the remote (sub)transactions in
parallel to improve performance. This is enabled by the server option
"parallel_commit". The default is false.
Etsuro Fujita, reviewed by Fujii Masao and David Zhang.
Discussion: http://postgr.es/m/CAPmGK17dAZCXvwnfpr1eTfknTGdt%3DhYTV9405Gt5SqPOX8K84w%40mail.gmail.com
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Commit 75d22069e tried to throw a warning for setting a custom GUC whose
prefix belongs to a previously-loaded extension, if there is no such GUC
defined by the extension. But that caused unstable behavior with
parallel workers, because workers don't necessarily load extensions and
GUCs in the same order their leader did. To make that work safely, we
have to completely disallow the case. We now actually remove any such
GUCs at the time of initial extension load, and then throw an error not
just a warning if you try to add one later. While this might create a
compatibility issue for a few people, the improvement in error-detection
capability seems worth it; it's hard to believe that there's any good
use-case for choosing such GUC names.
This also un-reverts 5609cc01c (Rename EmitWarningsOnPlaceholders() to
MarkGUCPrefixReserved()), since that function's old name is now even
more of a misnomer.
Florin Irion and Tom Lane
Discussion: https://postgr.es/m/1902182.1640711215@sss.pgh.pa.us
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Commit 6e0cb3dec1 allowed postgres_fdw.application_name to include
escape sequences %a (application name), %d (database name), %u (user name)
and %p (pid). In addition to them, this commit makes it support
the escape sequences for session ID (%c) and cluster name (%C).
These are helpful to investigate where each remote transactions came from.
Author: Fujii Masao
Reviewed-by: Ryohei Takahashi, Kyotaro Horiguchi
Discussion: https://postgr.es/m/1041dc9a-c976-049f-9f14-e7d94c29c4b2@oss.nttdata.com
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This routine is a no-op since dd04e95 from 2003, with a macro kept
around for compatibility purposes. This has led to the same code
patterns being copy-pasted around for no effect, sometimes in confusing
ways like in pg_logical_slot_get_changes_guts() from logical.c where the
code was actually incorrect.
This issue has been discussed on two different threads recently, so
rather than living with this legacy, remove any uses of this routine in
the C code to simplify things. The compatibility macro is kept to avoid
breaking any out-of-core modules that depend on it.
Reported-by: Tatsuhito Kasahara, Justin Pryzby
Author: Tatsuhito Kasahara
Discussion: https://postgr.es/m/20211217200419.GQ17618@telsasoft.com
Discussion: https://postgr.es/m/CAP0=ZVJeeYfAeRfmzqAF2Lumdiv4S4FewyBnZd4DPTrsSQKJKw@mail.gmail.com
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postgresReScanForeignScan().
Commit 27e1f1456 failed to process a pending asynchronous request made
for a given ForeignScan node in postgresReScanForeignScan() (if any) in
cases where we would only reset the next_tuple counter in that function,
contradicting the assumption that there should be no pending
asynchronous requests that have been made for async-capable subplans for
the parent Append node after ReScan. This led to an assert failure in
an assert-enabled build. I think this would also lead to mis-rewinding
the cursor in that function in the case where we have already fetched
one batch for the ForeignScan node and the asynchronous request has been
made for the second batch, because even in that case we would just reset
the counter when called from that function, so we would fail to execute
MOVE BACKWARD ALL.
To fix, modify that function to process the asynchronous request before
restarting the scan.
While at it, add a comment to a function to match other places.
Per bug #17344 from Alexander Lakhin. Back-patch to v14 where the
aforesaid commit came in.
Patch by me. Test case by Alexander Lakhin, adjusted by me. Reviewed
and tested by Alexander Lakhin and Dmitry Dolgov.
Discussion: https://postgr.es/m/17344-226b78b00de73a7e@postgresql.org
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execution.
Commit 27e1f1456 resets the per-connection states of connections used to
scan foreign tables asynchronously during abort cleanup at main
transaction end, but it failed to do so during subabort cleanup at
subtransaction end, leading to a segmentation fault when re-executing an
asynchronous-foreign-table-scan query in a transaction that was
cancelled in a subtransaction of it.
Fix by modifying pgfdw_abort_cleanup() to reset the per-connection state
of a given connection also when called for subabort cleanup. Also,
modify that function to do the reset in both the abort-cleanup and
subabort-cleanup cases if necessary, to save cycles, and improve a
comment on it a little bit.
Back-patch to v14 where the aforesaid commit came in.
Reviewed by Alexander Pyhalov
Discussion: https://postgr.es/m/CAPmGK14cCV-JA7kNsyt2EUTKvZ4xkr2LNRthi1U1C3cqfGppAw@mail.gmail.com
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Before, SQL-level boolean constants were represented by a string with
a cast, and internal Boolean values in DDL commands were usually
represented by Integer nodes. This takes the place of both of these
uses, making the intent clearer and having some amount of type safety.
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/8c1a2e37-c68d-703c-5a83-7a6077f4f997@enterprisedb.com
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Backpatch-through: 10
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Commit 449ab63505 added postgres_fdw.application_name GUC that specifies
a value for application_name configuration parameter used when postgres_fdw
establishes a connection to a foreign server. Also commit 6e0cb3dec1
allowed it to include escape sequences. Both commits added the regression
tests for the GUC, but those tests were reverted by commits 98dbef90eb and
5e64ad3697 because they were unstable and caused some buildfarm members
to report the failure.
This is the third try to add the regression test for
postgres_fdw.application_name GUC.
One of issues to make the test unstable was to have used
postgres_fdw_disconnect_all() to close the existing remote connections.
The test expected that the remote connection and its corresponding backend
at the remote server disappeared just after postgres_fdw_disconnect_all()
was executed, but it could take a bit time for them to disappear.
To make sure that they exit, this commit makes the test use
pg_terminate_backend() with the timeout at the remote server, instead.
If the timeout is set to greater than zero, this function waits until
they are actually terminated (or until the given time has passed).
Another issue was that the test didn't take into consideration the case
where postgres_fdw.application_name containing some escape sequences was
converted to the string larger than NAMEDATALEN. In this case it was
truncated to less than NAMEDATALEN when it's passed to the remote server,
but the test expected wrongly that full string of application_name was
always viewable. This commit changes the test so that it can handle that case.
Author: Fujii Masao
Reviewed-by: Masahiko Sawada, Hayato Kuroda, Kyotaro Horiguchi
Discussion: https://postgr.es/m/3220909.1631054766@sss.pgh.pa.us
Discussion: https://postgr.es/m/20211224.180006.2247635208768233073.horikyota.ntt@gmail.com
Discussion: https://postgr.es/m/e7b61420-a97b-8246-77c4-a0d48fba5a45@oss.nttdata.com
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Revert commits 5609cc01c, 2ed8a8cc5, and 75d22069e until we have
a less broken idea of how this should work in parallel workers.
Per buildfarm.
Discussion: https://postgr.es/m/1640909.1640638123@sss.pgh.pa.us
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This seems like a clearer name for what it does now.
Provide a compatibility macro so that extensions don't have to convert
to the new name right away.
Discussion: https://postgr.es/m/116024.1640111629@sss.pgh.pa.us
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Commit 6e0cb3dec1 added the tests that check that escape sequences in
postgres_fdw.application_name setting are replaced with status information
expectedly. But they were unstable and caused some buildfarm
members to report the failure. This commit reverts those unstable tests.
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