941697c3 changed ProcArrayAdd()/Remove() substantially. As reported by
zhanyi, I missed that due to the introduction of the PGPROC->pgxactoff
ProcArrayRemove() does not need to search for the position in
procArray->pgprocnos anymore - that's pgxactoff. Remove the search loop.

The removal of the search loop reduces assertion coverage a bit - but we can
easily do better than before by adding assertions to other loops over
pgprocnos elements.

Also do a bit of cleanup, mostly by reducing line lengths by introducing local
helper variables and adding newlines.

Author: zhanyi <w@hidva.com>
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/tencent_5624AA3B116B3D1C31CA9744@qq.com

Reported-by: Justin Pryzby

We were already reporting it, but only after the parallel workers were
finished, which is visibly much later than what happens in a serial
build.

With this change we report it when the leader starts its own sort phase
when participating in the build (the normal case).  Now this might
happen a little later than when the workers start their sorting phases,
but a) communicating the actual phase start from workers is likely to be
a hassle, and b) the sort phase start is pretty fuzzy anyway, since
sorting per se is actually initiated by tuplesort.c internally earlier
than tuplesort_performsort() is called.

Backpatch to pg12, where the progress reporting code for CREATE INDEX
went in.
Reported-by: Tomas Vondra <tomas.vondra@enterprisedb.com>
Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-by: Greg Nancarrow <gregn4422@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/1128176d-1eee-55d4-37ca-e63644422adb

apply_handle_tuple_routing(), having detected and reported that
the tuple it needed to update didn't exist, tried to update that
tuple anyway, leading to a null-pointer dereference.

logicalrep_partition_open() failed to ensure that the
LogicalRepPartMapEntry it built for a partition was fully
independent of that for the partition root, leading to
trouble if the root entry was later freed or rebuilt.

Meanwhile, on the publisher's side, pgoutput_change() sometimes
attempted to apply execute_attr_map_tuple() to a NULL tuple.

The first of these was reported by Sergey Bernikov in bug #17055;
I found the other two while developing some test cases for this
sadly under-tested code.

Diagnosis and patch for the first issue by Amit Langote; patches
for the others by me; new test cases by me.  Back-patch to v13
where this logic came in.

Discussion: https://postgr.es/m/17055-9ba800ec8522668b@postgresql.org

Commit acb7e4eb added a new implementation for PQsendQuery so that
it works in pipeline mode (by using extended query protocol), but it
behaves differently from the 'Q' message (in simple query protocol) used
by regular implementation: the new one doesn't close the unnamed portal.
Change the new code to have identical behavior to the old.
Reported-by: Yura Sokolov <y.sokolov@postgrespro.ru>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/202106072107.d4i55hdscxqj@alvherre.pgsql

Per 96540f80; the awkward API introduced by c6550776 is no
longer needed.

Author: Andres Freund <andres@anarazel.de>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/20210408020913.zzprrlvqyvlt5cyy@alap3.anarazel.de

Commit b663a413 introduced bulk inserts for FDW, but the handling of
tuple slots turned out to be problematic for two reasons. Firstly, the
slots were re-created for each individual batch. Secondly, all slots
referenced the same tuple descriptor - with reasonably small batches
this is not an issue, but with large batches this triggers O(N^2)
behavior in the resource owner code.

These two issues work against each other - to reduce the number of times
a slot has to be created/dropped, larger batches are needed. However,
the larger the batch, the more expensive the resource owner gets. For
practical batch sizes (100 - 1000) this would not be a big problem, as
the benefits (latency savings) greatly exceed the resource owner costs.
But for extremely large batches it might be much worse, possibly even
losing with non-batching mode.

Fixed by initializing tuple slots only once (and reusing them across
batches) and by using a new tuple descriptor copy for each slot.

Discussion: https://postgr.es/m/ebbbcc7d-4286-8c28-0272-61b4753af761%40enterprisedb.com

The code added to mark replication slots invalid in commit c6550776
had the race condition that a slot can be dropped or advanced
concurrently with checkpointer trying to invalidate it.  Rewrite the
code to close those races.

The changes to ReplicationSlotAcquire's API added with c6550776 are
not necessary anymore.  To avoid an ABI break in released branches, this
commit leaves that unchanged; it'll be changed in a master-only commit
separately.

Backpatch to 13, where this code first appeared.
Reported-by: Andres Freund <andres@anarazel.de>
Author: Andres Freund <andres@anarazel.de>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/20210408001037.wfmk6jud36auhfqm@alap3.anarazel.de

The list of options provided by the tab completion was outdated for the
following commands:
- ALTER SUBSCRIPTION
- CREATE SUBSCRIPTION
- ALTER PUBLICATION
- CREATE PUBLICATION

Author: Vignesh C
Reviewed-by: Bharath Rupireddy
Discussion: https://postgr.es/m/CALDaNm18oHDFu6SFCHE=ZbiO153Fx7E-L1MG0YyScbaDV--U+A@mail.gmail.com

Resolve the disagreement with nodes/*funcs.c field order in favor of the
latter, which is better-aligned with the IndexStmt field order.  This
field is new in v14.

Discussion: https://postgr.es/m/20210611045546.GA573364@rfd.leadboat.com

We have a dozen PQset*() functions.  PQresultSetInstanceData() and this
were the libpq setter functions having a different word order.  Adopt
the majority word order.

Reviewed by Alvaro Herrera and Robert Haas, though this choice of name
was not unanimous.

Discussion: https://postgr.es/m/20210605060555.GA216695@rfd.leadboat.com

We've accumulated quite a mix of instances of "an SQL" and "a SQL" in the
documents.  It would be good to be a bit more consistent with these.

The most recent version of the SQL standard I looked at seems to prefer
"an SQL".  That seems like a good lead to follow, so here we change all
instances of "a SQL" to become "an SQL".  Most instances correctly use
"an SQL" already, so it also makes sense to use the dominant variation in
order to minimise churn.

Additionally, there were some other abbreviations that needed to be
adjusted. FSM, SSPI, SRF and a few others.  Also fix some pronounceable,
abbreviations to use "a" instead of "an".  For example, "a SASL" instead
of "an SASL".

Here I've only adjusted the documents and error messages.  Many others
still exist in source code comments.  Translator hint comments seem to be
the biggest culprit.  It currently does not seem worth the churn to change
these.

Discussion: https://postgr.es/m/CAApHDvpML27UqFXnrYO1MJddsKVMQoiZisPvsAGhKE_tsKXquw%40mail.gmail.com

Commit 2453ea14 redefined pg_proc.proargtypes to include the types of
OUT parameters, for procedures only.  While that had some advantages
for implementing the SQL-spec behavior of DROP PROCEDURE, it was pretty
disastrous from a number of other perspectives.  Notably, since the
primary key of pg_proc is name + proargtypes, this made it possible to
have multiple procedures with identical names + input arguments and
differing output argument types.  That would make it impossible to call
any one of the procedures by writing just NULL (or "?", or any other
data-type-free notation) for the output argument(s).  The change also
seems likely to cause grave confusion for client applications that
examine pg_proc and expect the traditional definition of proargtypes.

Hence, revert the definition of proargtypes to what it was, and
undo a number of complications that had been added to support that.

To support the SQL-spec behavior of DROP PROCEDURE, when there are
no argmode markers in the command's parameter list, we perform the
lookup both ways (that is, matching against both proargtypes and
proallargtypes), succeeding if we get just one unique match.
In principle this could result in ambiguous-function failures
that would not happen when using only one of the two rules.
However, overloading of procedure names is thought to be a pretty
rare usage, so this shouldn't cause many problems in practice.
Postgres-specific code such as pg_dump can defend against any
possibility of such failures by being careful to specify argmodes
for all procedure arguments.

This also fixes a few other bugs in the area of CALL statements
with named parameters, and improves the documentation a little.

catversion bump forced because the representation of procedures
with OUT arguments changes.

Discussion: https://postgr.es/m/3742981.1621533210@sss.pgh.pa.us

It turns out that worker.c's code path for TRUNCATE was also
careless about establishing a snapshot while executing user-defined
code, allowing the checks added by commit 84f5c290 to fail when
a trigger is fired in that context.

We could just wrap Push/PopActiveSnapshot around the truncate call,
but it seems better to establish a policy of holding a snapshot
throughout execution of a replication step.  To help with that and
possible future requirements, replace the previous ensure_transaction
calls with pairs of begin/end_replication_step calls.

Per report from Mark Dilger.  Back-patch to v11, like the previous
changes.

Discussion: https://postgr.es/m/B4A3AF82-79ED-4F4C-A4E5-CD2622098972@enterprisedb.com

Previously, we left the EPQ sub-executor alone until ExecEndLockRows.
This caused any buffer pins or other resources that it might hold to
remain held until ExecutorEnd, which in some code paths means that
they are held till the Portal is closed.  That can cause user-visible
problems, such as blocking VACUUM; and it's unlike the behavior of
ordinary table-scanning nodes, which will have released all buffer
pins by the time they return an EOF indication.

We can make LockRows work more like other plan nodes by calling
EvalPlanQualEnd just before returning NULL.  We still need to call it
in ExecEndLockRows in case the node was not run to completion, but in
the normal case the second call does nothing and costs little.

Per report from Yura Sokolov.  In principle this is a longstanding
bug, but in view of the lack of other complaints and the low severity
of the consequences, I chose not to back-patch.

Discussion: https://postgr.es/m/4aa370cb91ecf2f9885d98b80ad1109c@postgrespro.ru

Buildfarm member hamerkop has been reporting that two cases in
connect/test5.pgc show different error messages than the test expects,
because since commit ffa2e467 libpq's connection failure messages
are exposing the fact that a GSS-encrypted connection was attempted
and failed.  That's pretty interesting information in itself, and
I certainly don't wish to shoot the messenger, but we need to do
something to stabilize the ECPG results.

For the second of these two failure cases, we can add the
gssencmode=disable option to prevent the discrepancy.  However,
that solution is problematic for the first failure, because the only
unique thing about that case is that it's testing a completely-omitted
connection target; there's noplace to add the option without defeating
the point of the test case.  After some thrashing around with
alternative fixes that turned out to have undesirable side-effects,
the most workable answer is just to give up and remove that test case.
Perhaps we can revert this later, if we figure out why the GSS code
is misbehaving in hamerkop's environment.

Thanks to Michael Paquier for exploration of alternatives.

Discussion: https://postgr.es/m/YLRZH6CWs9N6Pusy@paquier.xyz

One of these functions is new in PostgreSQL 14; might as well start it
out right.

Per buildfarm member conchuela and Kyotaro Horiguchi, it's possible
for the WAL segment that the cascading standby needs to be removed
too quickly. Hopefully this will prevent that.

Kyotaro Horiguchi

Discussion: http://postgr.es/m/20210610.101240.1270925505780628275.horikyota.ntt@gmail.com

Discussion: https://postgr.es/m/CAApHDvrbyJNOPBws4RUhXghZ7+TBjtdO-rznTsqZECuowNorXg@mail.gmail.com

This only happens if (1) the new standby has no WAL available locally,
(2) the new standby is starting from the old timeline, (3) the promotion
happened in the WAL segment from which the new standby is starting,
(4) the timeline history file for the new timeline is available from
the archive but the WAL files for are not (i.e. this is a race),
(5) the WAL files for the new timeline are available via streaming,
and (6) recovery_target_timeline='latest'.

Commit ee994272 introduced this
logic and was an improvement over the previous code, but it mishandled
this case. If recovery_target_timeline='latest' and restore_command is
set, validateRecoveryParameters() can change recoveryTargetTLI to be
different from receiveTLI. If streaming is then tried afterward,
expectedTLEs gets initialized with the history of the wrong timeline.
It's supposed to be a list of entries explaining how to get to the
target timeline, but in this case it ends up with a list of entries
explaining how to get to the new standby's original timeline, which
isn't right.

Dilip Kumar and Robert Haas, reviewed by Kyotaro Horiguchi.

Discussion: http://postgr.es/m/CAFiTN-sE-jr=LB8jQuxeqikd-Ux+jHiXyh4YDiZMPedgQKup0g@mail.gmail.com

The set of subcommands supported by \dAp, \do and \dy was described
incorrectly in psql's --help.  The documentation was already consistent
with the code.

Reported-by: inoas, from IRC
Author: Matthijs van der Vleuten
Reviewed-by: Neil Chen
Discussion: https://postgr.es/m/6a984e24-2171-4039-9050-92d55e7b23fe@www.fastmail.com
Backpatch-through: 9.6

Further thought about bug #17050 suggests that it's a good idea
to use CURSOR_OPT_NO_SCROLL for the implicit cursor opened by
a plpgsql FOR-over-query loop.  This ensures that, if somebody
commits inside the loop, PersistHoldablePortal won't try to
rewind and re-read the cursor.  While we'd have selected NO_SCROLL
anyway if FOR UPDATE/SHARE appears in the query, there are other
hazards with volatile functions; and in any case, it's silly to
expend effort storing rows that we know for certain won't be needed.

(While here, improve the comment in exec_run_select, which was a bit
confused about the rationale for when we can use parallel mode.
Cursor operations aren't a hazard for nameless portals.)

This wasn't an issue until v11, which introduced the possibility
of persisting such cursors.  Hence, back-patch to v11.

Per bug #17050 from Алексей Булгаков.

Discussion: https://postgr.es/m/17050-f77aa827dc85247c@postgresql.org

PersistHoldablePortal has long assumed that it should store the
entire output of the query-to-be-persisted, which requires rewinding
and re-reading the output.  This is problematic if the query is not
stable: we might get different row contents, or even a different
number of rows, which'd confuse the cursor state mightily.

In the case where the cursor is NO SCROLL, this is very easy to
solve: just store the remaining query output, without any rewinding,
and tweak the portal's cursor state to match.  Aside from removing
the semantic problem, this could be significantly more efficient
than storing the whole output.

If the cursor is scrollable, there's not much we can do, but it
was already the case that scrolling a volatile query's result was
pretty unsafe.  We can just document more clearly that getting
correct results from that is not guaranteed.

There are already prohibitions in place on using SCROLL with
FOR UPDATE/SHARE, which is one way for a SELECT query to have
non-stable results.  We could imagine prohibiting SCROLL when
the query contains volatile functions, but that would be
expensive to enforce.  Moreover, it could break applications
that work just fine, if they have functions that are in fact
stable but the user neglected to mark them so.  So settle for
documenting the hazard.

While this problem has existed in some guise for a long time,
it got a lot worse in v11, which introduced the possibility
of persisting plpgsql cursors (perhaps implicit ones) even
when they violate the rules for what can be marked WITH HOLD.
Hence, I've chosen to back-patch to v11 but not further.

Per bug #17050 from Алексей Булгаков.

Discussion: https://postgr.es/m/17050-f77aa827dc85247c@postgresql.org

Protocol v2 was last used in PG 7.3, not 7.2.

Reported-by: Tatsuo Ishii

Discussion: https://postgr.es/m/20210608.091329.906837606658882674.t-ishii@sraoss.co.jp

The FE/BE protocol identifies parameters with an Int16 index, which
limits the maximum number of parameters per query to 65535. With
batching added to postges_fdw this limit is much easier to hit, as
the whole batch is essentially a single query, making this error much
easier to hit.

The failures are a bit unpredictable, because it also depends on the
number of columns in the query. So instead of just failing, this patch
tweaks the batch_size to not exceed the maximum number of parameters.
Reported-by: Hou Zhijie <houzj.fnst@cn.fujitsu.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Discussion: https://postgr.es/m/OS0PR01MB571603973C0AC2874AD6BF2594299%40OS0PR01MB5716.jpnprd01.prod.outlook.com

Commit 8e03eb92 reverted a bit too much code, reintroducing one of the
issues fixed by 39b66a91 - a page might have been left partially empty
after relcache invalidation.

Reported-By: Tom Lane
Author: Masahiko Sawada
Discussion: https://postgr.es/m/822752.1623032114@sss.pgh.pa.us
Discussion: https://postgr.es/m/CAD21AoA%3D%3Df2VSw3c-Cp_y%3DWLKHMKc1D6s7g3YWsCOvgaYPpJcg%40mail.gmail.com

gram.y should discard NULL pointers (empty statements) when
assembling a routine_body_stmt_list, as it does for other
sorts of statement lists.

Julien Rouhaud and Tom Lane, per report from Noah Misch.

Discussion: https://postgr.es/m/20210606044418.GA297923@rfd.leadboat.com

Fix handling of NULL host name (possibly by using hostaddr).  It
previously crashed.  Also, we should look at connhost, not pghost, to
handle multi-host specifications.

Also remove an unnecessary SSL_CTX_free().
Reported-by: Jacob Champion <pchampion@vmware.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://www.postgresql.org/message-id/504c276ab6eee000bb23d571ea9b0ced4250774e.camel@vmware.com

Add a note about asynchronous execution by postgres_fdw when applied to
Append nodes that contain synchronous subplan(s) as well.  Follow-up for
commit 27e1f145.

Andrey Lepikhov and Etsuro Fujita

Discussion: https://postgr.es/m/58fa2aa5-07f5-80b5-59a1-fec8a349fee7%40postgrespro.ru

The use of this function is limited to superusers and the code includes
a hardcoded check for that.  However, the code would look for the PGPROC
entry to signal for the memory dump before checking if the user is a
superuser or not, which does not make sense if we know that an error
will be returned.  Note that the code would let one know if a process
was a PostgreSQL process or not even for non-authorized users, which is
not the case now, but this avoids taking ProcArrayLock that will most
likely finish by being unnecessary.

Thanks to Julien Rouhaud and Tom Lane for the discussion.

Discussion: https://postgr.es/m/YLxw1uVGIAP5uMPl@paquier.xyz

We have outNode() coverage for all path nodes, but this one was
missed when it was added.

If autovacuum comes along just after we fill table test_seg with
some data, it will update the stats to the point where we prefer
a plain indexscan over a bitmap scan, breaking the expected
output (as well as the point of the test case).  To fix, just
force a bitmap scan to be chosen here.

This has evidently been wrong since commit de1d042f.  It's not
clear why we just recently saw any buildfarm failures due to it;
but prairiedog has failed twice on this test in the past week.
Hence, backpatch to v11 where this test case came in.

An incorrectly-encoded multibyte character near the end of a string
could cause various processing loops to run past the string's
terminating NUL, with results ranging from no detectable issue to
a program crash, depending on what happens to be in the following
memory.

This isn't an issue in the server, because we take care to verify
the encoding of strings before doing any interesting processing
on them.  However, that lack of care leaked into client-side code
which shouldn't assume that anyone has validated the encoding of
its input.

Although this is certainly a bug worth fixing, the PG security team
elected not to regard it as a security issue, primarily because
any untrusted text should be sanitized by PQescapeLiteral or
the like before being incorporated into a SQL or psql command.
(If an app fails to do so, the same technique can be used to
cause SQL injection, with probably much more dire consequences
than a mere client-program crash.)  Those functions were already
made proof against this class of problem, cf CVE-2006-2313.

To fix, invent PQmblenBounded() which is like PQmblen() except it
won't return more than the number of bytes remaining in the string.
In HEAD we can make this a new libpq function, as PQmblen() is.
It seems imprudent to change libpq's API in stable branches though,
so in the back branches define PQmblenBounded as a macro in the files
that need it.  (Note that just changing PQmblen's behavior would not
be a good idea; notably, it would completely break the escaping
functions' defense against this exact problem.  So we just want a
version for those callers that don't have any better way of handling
this issue.)

Per private report from houjingyi.  Back-patch to all supported branches.

When run on a server using default_toast_compression set to LZ4, this
test would fail because of a consistency issue with the order of the
tuples treated.  LZ4 causes one tuple to be stored inline instead of
getting externalized.  As the goal of this test is to check after data
stored externally, stick to pglz as the compression algorithm used, so
as all data of this test is stored the way it should.

Analyzed-by: Dilip Kumar
Discussion: https://postgr.es/m/YLrDWxJgM8WWMoCg@paquier.xyz

Commit 19890a06 added the option to enable two_phase commits via
pg_create_logical_replication_slot but didn't extend the support of same
in replication protocol. However, by mistake, it added the two_phase
variable in CreateReplicationSlotCmd which is required only when we extend
the replication protocol.

Reported-by: Jeff Davis
Author: Ajin Cherian
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/64b9f783c6e125f18f88fbc0c0234e34e71d8639.camel@j-davis.com

In cases where run-time pruning isn't required, the synchronous and
asynchronous subplans for an async-aware Append node determined using
classify_matching_subplans() should be re-used when rescanning the node,
but the previous code re-determined them using that function repeatedly
each time when rescanning the node, leading to incorrect results in a
normal build and an Assert failure in an Assert-enabled build as that
function doesn't assume that it's called repeatedly in such cases.  Fix
the code as mentioned above.

My oversight in commit 27e1f145.

While at it, initialize async-related pointers/variables to NULL/zero
explicitly in ExecInitAppend() and ExecReScanAppend(), just to be sure.
(The variables would have been set to zero before we get to the latter
function, but let's do so.)

Reviewed-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/CAPmGK16Q4B2_KY%2BJH7rb7wQbw54AUprp7TMekGTd2T1B62yysQ%40mail.gmail.com

Other equalfuncs.c checks on CoercionForm fields use
COMPARE_COERCIONFORM_FIELD (which makes them no-ops),
but commit 40c24bfe neglected to make _equalFuncCall
do likewise.  Fix that.

This is only strictly correct if FuncCall.funcformat has
no semantic effect, instead just determining ruleutils.c
display formatting.  40c24bfe added a couple of checks
in parse analysis that could break that rule; but on closer
inspection, they're redundant, so just take them out again.

Per report from Noah Misch.

Discussion: https://postgr.es/m/20210606063331.GC297923@rfd.leadboat.com

Commit a4d75c86 added a new flag, tracking if the statement was
processed by transformStatsStmt(), but failed to add this flag to
nodes/*funcs.c.

Catversion bump, due to adding a flag to copy/equal/out functions.

Reported-by: Noah Misch
Discussion: https://postgr.es/m/ad7891d2-e90c-b446-9fe2-7419143847d7%40enterprisedb.com

catversion bump due to readfuncs.c field order change.