This reverts commit 778e78ae.  Per
further discussion, that doesn't seem to be the best possible fix.

Discussion: http://postgr.es/m/CAA4eK1LW2aFKzY3=vwvc=t-juzPPVWP2uT1bpx_MeyEqnM+p8g@mail.gmail.com

Reported-by: Noah Misch <noah@leadboat.com>

I noticed that _SPI_execute_plan initially sets spierrcontext.arg = NULL,
and only fills it in some time later.  If an error were to happen in
between, _SPI_error_callback would try to dereference the null pointer.
This is unlikely --- there's not much between those points except
push-snapshot calls --- but it's clearly not impossible.  Tweak the
callback to do nothing if the pointer isn't set yet.

It's been like this for awhile, so back-patch to all supported branches.

Reported by Robins Tharakan

Notably, this permits linking to the 32-bit Perl binaries advertised on
perl.org, namely Strawberry Perl and ActivePerl.  This has a side effect
of permitting linking to binaries built with obsolete MSVC versions.

By default, MSVC 2012 and later require a "safe exception handler table"
in each binary.  MinGW-built, 32-bit DLLs lack the relevant exception
handler metadata, so linking to them failed with error LNK2026.  Restore
the semantics of MSVC 2010, which omits the table from a given binary if
some linker input lacks metadata.  This has no effect on 64-bit builds
or on MSVC 2010 and earlier.  Back-patch to 9.3 (all supported
versions).

Reported by Victor Wagner.

Discussion: https://postgr.es/m/20160326154321.7754ab8f@wagner.wagner.home

Commits 5a5c2fec and
b5178c5d introduced support for modern
MSVC-built, 32-bit Perl, but they broke use of MinGW-built, 32-bit Perl
distributions like Strawberry Perl and modern ActivePerl.  Perl has no
robust means to report whether it expects a -D_USE_32BIT_TIME_T ABI, so
test this.  Back-patch to 9.3 (all supported versions).

The chief alternative was a heuristic of adding -D_USE_32BIT_TIME_T when
$Config{gccversion} is nonempty.  That banks on every gcc-built Perl
using the same ABI.  gcc could change its default ABI the way MSVC once
did, and one could build Perl with gcc and the non-default ABI.

The GNU make build system could benefit from a similar test, without
which it does not support MSVC-built Perl.  For now, just add a comment.
Most users taking the special step of building Perl with MSVC probably
build PostgreSQL with MSVC.

Discussion: https://postgr.es/m/20171130041441.GA3161526@rfd.leadboat.com

Those cases currently crash and supporting them is more work then
originally thought, so we'll just prohibit these scenarios for now.

Author: Michael Paquier <michael.paquier@gmail.com>
Reviewed-by: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
Reported-by: Мансур Галиев <gomer94@yandex.ru>
Bug: #14866

Reported-by: Masahiko Sawada <sawada.mshk@gmail.com>

Add support to the SCRAM exchange for clients that support channel
binding, such as PostgreSQL version 11 and beyond.  If such a client
encounters a PostgreSQL 10 server that does not support channel binding,
it will send a channel binding flag 'y', meaning the client supports
channel binding but thinks the server does not.  But PostgreSQL 10
erroneously did not accept that flag.  This would cause connections to
fail if a version 11 client connects to a version 10 server with SCRAM
authentication over SSL.

Author: Michael Paquier <michael.paquier@gmail.com>

A COPY into a table should apply identity sequence values just like it
does for ordinary defaults.  This was previously forgotten, leading to
null values being inserted, which in turn would fail because identity
columns have not-null constraints.

Author: Michael Paquier <michael.paquier@gmail.com>
Reported-by: Steven Winfield <steven.winfield@cantabcapital.com>
Bug: #14952

When a worker is flagged as BGW_NEVER_RESTART and we fail to start it,
or if it is not marked BGW_NEVER_RESTART but is terminated before
startup succeeds, what BgwHandleStatus should be reported?  The
previous code really hadn't considered this possibility (as indicated
by the comments which ignore it completely) and would typically return
BGWH_NOT_YET_STARTED, but that's not a good answer, because then
there's no way for code using GetBackgroundWorkerPid() to tell the
difference between a worker that has not started but will start
later and a worker that has not started and will never be started.
So, when this case happens, return BGWH_STOPPED instead.  Update the
comments to reflect this.

The preceding fix by itself is insufficient to fix the problem,
because the old code also didn't send a notification to the process
identified in bgw_notify_pid when startup failed.  That might've
been technically correct under the theory that the status of the
worker was BGWH_NOT_YET_STARTED, because the status would indeed not
change when the worker failed to start, but now that we're more
usefully reporting BGWH_STOPPED, a notification is needed.

Without these fixes, code which starts background workers and then
uses the recommended APIs to wait for those background workers to
start would hang indefinitely if the postmaster failed to fork a
worker.

Amit Kapila and Robert Haas

Discussion: http://postgr.es/m/CAA4eK1KDfKkvrjxsKJi3WPyceVi3dH1VCkbTJji2fuwKuB=3uw@mail.gmail.com

Reported-by: Dave Page <dpage@pgadmin.org>

When a Gather or Gather Merge node is started and stopped multiple
times, the old code wouldn't reset the shared state between executions,
potentially resulting in dramatically inflated instrumentation data
for nodes beneath it.  (The per-worker instrumentation ended up OK,
I think, but the overall totals were inflated.)

Report by hubert depesz lubaczewski.  Analysis and fix by Amit Kapila,
reviewed and tweaked a bit by me.

Discussion: http://postgr.es/m/20171127175631.GA405@depesz.com

This makes life easier for extension authors who wish to support
Windows.

Brian Cloutier, slightly amended by me.

Discussion: http://postgr.es/m/CAJCy68fscdNhmzFPS4kyO00CADkvXvEa-28H-OtENk-pa2OTWw@mail.gmail.com

This ensures that automatically generated HTML anchors don't change in
every build.

This patch fixes a couple of low-probability bugs that could lead to
reporting an irrelevant errno value (and hence possibly a wrong SQLSTATE)
concerning directory-open or file-open failures.  It also fixes places
where we took shortcuts in reporting such errors, either by using elog
instead of ereport or by using ereport but forgetting to specify an
errcode.  And it eliminates a lot of just plain redundant error-handling
code.

In service of all this, export fd.c's formerly-static function
ReadDirExtended, so that external callers can make use of the coding
pattern

	dir = AllocateDir(path);
	while ((de = ReadDirExtended(dir, path, LOG)) != NULL)

if they'd like to treat directory-open failures as mere LOG conditions
rather than errors.  Also fix FreeDir to be a no-op if we reach it
with dir == NULL, as such a coding pattern would cause.

Then, remove code at many call sites that was throwing an error or log
message for AllocateDir failure, as ReadDir or ReadDirExtended can handle
that job just fine.  Aside from being a net code savings, this gets rid of
a lot of not-quite-up-to-snuff reports, as mentioned above.  (In some
places these changes result in replacing a custom error message such as
"could not open tablespace directory" with more generic wording "could not
open directory", but it was agreed that the custom wording buys little as
long as we report the directory name.)  In some other call sites where we
can't just remove code, change the error reports to be fully
project-style-compliant.

Also reorder code in restoreTwoPhaseData that was acquiring a lock
between AllocateDir and ReadDir; in the unlikely but surely not
impossible case that LWLockAcquire changes errno, AllocateDir failures
would be misreported.  There is no great value in opening the directory
before acquiring TwoPhaseStateLock, so just do it in the other order.

Also fix CheckXLogRemoved to guarantee that it preserves errno,
as quite a number of call sites are implicitly assuming.  (Again,
it's unlikely but I think not impossible that errno could change
during a SpinLockAcquire.  If so, this function was broken for its
own purposes as well as breaking callers.)

And change a few places that were using not-per-project-style messages,
such as "could not read directory" when "could not open directory" is
more correct.

Back-patch the exporting of ReadDirExtended, in case we have occasion
to back-patch some fix that makes use of it; it's not needed right now
but surely making it global is pretty harmless.  Also back-patch the
restoreTwoPhaseData and CheckXLogRemoved fixes.  The rest of this is
essentially cosmetic and need not get back-patched.

Michael Paquier, with a bit of additional work by me

Discussion: https://postgr.es/m/CAB7nPqRpOCxjiirHmebEFhXVTK7V5Jvw4bz82p7Oimtsm3TyZA@mail.gmail.com

There's no good reason that the multicolumn stats stuff shouldn't work on
booleans.  But it looked only for "Var = pseudoconstant" clauses, and it
will seldom find those for boolean Vars, since earlier phases of planning
will fold "boolvar = true" or "boolvar = false" to just "boolvar" or
"NOT boolvar" respectively.  Improve dependencies_clauselist_selectivity()
to recognize such clauses as equivalent to equality restrictions.

This fixes a failure of the extended stats mechanism to apply in a case
reported by Vitaliy Garnashevich.  It's not a complete solution to his
problem because the bitmap-scan costing code isn't consulting extended
stats where it should, but that's surely an independent issue.

In passing, improve some comments, get rid of a NumRelids() test that's
redundant with the preceding bms_membership() test, and fix
dependencies_clauselist_selectivity() so that estimatedclauses actually
is a pure output argument as stated by its API contract.

Back-patch to v10 where this code was introduced.

Discussion: https://postgr.es/m/73a4936d-2814-dc08-ed0c-978f76f435b0@gmail.com

Invoking the Makefile without an explicit target was building every
possible target instead of just the "all" target.  Back-patch to 9.3
(all supported versions).

This is simpler and more closely follows overwhelming precedent.

Report and patch by Mark Dilger.
Discussion: https://postgr.es/m/9A68FB88-5F45-4848-9926-8586E2D777D1@gmail.com

This is a mistakenly placed conditional in bf2a691e.

Reported by Justin Pryzby
Discussion: https://postgr.es/m/20171117214352.GE25796@telsasoft.com

Commit d4663350 changed things so
that shm_toc_lookup would fail with an error rather than silently
returning NULL in the hope that such failures would be reported
in a useful way rather than via a system crash.  However, it
overlooked the fact that the lookup of PARALLEL_KEY_ERROR_QUEUE
in ReinitializeParallelDSM is expected to fail when no DSM segment
was created in the first place; in that case, we end up with a
backend-private memory segment that still contains an entry for
PARALLEL_KEY_FIXED but no others.  Consequently a benign failure
to initialize parallelism can escalate into an elog(ERROR);
repair.

Discussion: http://postgr.es/m/CA+Tgmob8LFw55DzH1QEREpBEA9RJ_W_amhBFCVZ6WMwUhVpOqg@mail.gmail.com

If we have a plan that uses parallelism but are unable to execute it
using parallelism, for example due to a lack of available DSM
segments, then the EState's es_query_dsa will be NULL.  Parallel
bitmap heap scan needs to fall back to a non-parallel scan in such
cases.

Patch by me, reviewed by Dilip Kumar

Discussion: http://postgr.es/m/CAEepm=0kADK5inNf_KuemjX=HQ=PuTP0DykM--fO5jS5ePVFEA@mail.gmail.com

Allows triggers to operate correctly

Author: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Reported-by: Konstantin Knizhnik <k.knizhnik@postgrespro.ru>

heap_drop_with_catalog and ATExecDetachPartition neglected to check for
SearchSysCache failures, as noted in bugs #14927 and #14928 from Pan Bian.
Such failures are pretty unlikely, since we should already have some sort
of lock on the rel at these points, but it's neither a good idea nor
per project style to omit a check for failure.

Also, StorePartitionKey contained a syscache lookup that it never did
anything with, including never releasing the result.  Presumably the
reason why we don't see refcount-leak complaints is that the lookup
always fails; but in any case it's pretty useless, so remove it.

All of these errors were evidently introduced by the relation
partitioning feature.  Back-patch to v10 where that came in.

Amit Langote and Tom Lane

Discussion: https://postgr.es/m/20171127090105.1463.3962@wrigleys.postgresql.org
Discussion: https://postgr.es/m/20171127091341.1468.72696@wrigleys.postgresql.org

rewriteTargetListUD's processing is dependent on the relkind of the query's
target table.  That was fine at the time it was made to act that way, even
for queries on inheritance trees, because all tables in an inheritance tree
would necessarily be plain tables.  However, the 9.5 feature addition
allowing some members of an inheritance tree to be foreign tables broke the
assumption that rewriteTargetListUD's output tlist could be applied to all
child tables with nothing more than column-number mapping.  This led to
visible failures if foreign child tables had row-level triggers, and would
also break in cases where child tables belonged to FDWs that used methods
other than CTID for row identification.

To fix, delay running rewriteTargetListUD until after the planner has
expanded inheritance, so that it is applied separately to the (already
mapped) tlist for each child table.  We can conveniently call it from
preprocess_targetlist.  Refactor associated code slightly to avoid the
need to heap_open the target relation multiple times during
preprocess_targetlist.  (The APIs remain a bit ugly, particularly around
the point of which steps scribble on parse->targetList and which don't.
But avoiding such scribbling would require a change in FDW callback APIs,
which is more pain than it's worth.)

Also fix ExecModifyTable to ensure that "tupleid" is reset to NULL when
we transition from rows providing a CTID to rows that don't.  (That's
really an independent bug, but it manifests in much the same cases.)

Add a regression test checking one manifestation of this problem, which
was that row-level triggers on a foreign child table did not work right.

Back-patch to 9.5 where the problem was introduced.

Etsuro Fujita, reviewed by Ildus Kurbangaliev and Ashutosh Bapat

Discussion: https://postgr.es/m/20170514150525.0346ba72@postgrespro.ru

Andreas Karlsson

Originally, we palloc'd this buffer just barely big enough to hold the
largest xlog record seen so far.  It turns out that that can result in
valgrind complaints, because some compilers will emit code that assumes
it can safely fetch padding bytes at the end of a struct, and those
padding bytes were unallocated so far as aset.c was concerned.  We can
fix that by MAXALIGN'ing the palloc request size, ensuring that it is big
enough to include any possible padding that might've been omitted from
the on-disk record.

An additional objection to the original coding is that it could result in
many repeated palloc cycles, in the worst case where we see a series of
gradually larger xlog records.  We can ameliorate that cheaply by
imposing a minimum buffer size that's large enough for most xlog records.
BLCKSZ/2 was chosen after a bit of discussion.

In passing, remove an obsolete comment in struct xl_heap_new_cid that the
combocid field is free due to alignment considerations.  Perhaps that was
true at some point, but it's not now.

Back-patch to 9.5 where this code came in.

Discussion: https://postgr.es/m/E1eHa4J-0006hI-Q8@gemulon.postgresql.org

The various has_*_privilege() functions all support an optional
WITH GRANT OPTION added to the supported privilege types to test
whether the privilege is held with grant option. That is, all except
has_sequence_privilege() variations. Fix that.

Back-patch to all supported branches.

Discussion: https://postgr.es/m/005147f6-8280-42e9-5a03-dd2c1e4397ef@joeconway.com

Missed this dependency in commits 7cce222c et al.

Traditionally IANA has distributed their timezone data in pure source
form, replete with extensive historical comments.  As of release 2017c,
they've added a compact single-file format that omits comments and
abbreviates command keywords.  This form is way shorter than the pure
source, even before considering its allegedly better compressibility.
Hence, let's distribute the data in that form rather than pure source.

I'm pushing this now, rather than at the next timezone database update,
so that it's easy to confirm that this data file produces compiled zic
output that's identical to what we were getting before.

Discussion: https://postgr.es/m/1915.1511210334@sss.pgh.pa.us

hstoreUniquePairs() often called memcpy with equal source and destination
pointers.  Although this is almost surely harmless in practice, it's
undefined according to the letter of the C standard.  Some versions of
valgrind will complain about it, and some versions of libc as well
(cf. commit ad520ec4).  Tweak the code to avoid doing that.

Noted by Tomas Vondra.  Back-patch to all supported versions because
of the hazard of libc assertions.

Discussion: https://postgr.es/m/bf84d940-90d4-de91-19dd-612e011007f4@fuzzy.cz

When nodeValuesscan.c was written, it was impossible to have a SubPlan in
VALUES --- any sub-SELECT there would have to be uncorrelated and thereby
would produce an InitPlan instead.  We therefore took a shortcut in the
logic that throws away a ValuesScan's per-row expression evaluation data
structures.  This was broken by the introduction of LATERAL however; a
sub-SELECT containing a lateral reference produces a correlated SubPlan.

The cleanest fix for this would be to give up the optimization of
discarding the expression eval state.  But that still seems pretty
unappetizing for long VALUES lists.  It seems to work to just prevent
the subexpressions from hooking into the ValuesScan node's subPlan
list, so let's do that and see how well it works.  (If this breaks,
due to additional connections between the subexpressions and the outer
query structures, we might consider compromises like throwing away data
only for VALUES rows not containing SubPlans.)

Per bug #14924 from Christian Duta.  Back-patch to 9.3 where LATERAL
was introduced.

Discussion: https://postgr.es/m/20171124120836.1463.5310@wrigleys.postgresql.org

Improve query_is_distinct_for() to accept SRFs in the targetlist when
we can prove distinctness from a DISTINCT clause.  In that case the
de-duplication will surely happen after SRF expansion, so the proof
still works.  Continue to punt in the case where we'd try to prove
distinctness from GROUP BY (or, in the future, source relations).
To do that, we'd have to determine whether the SRFs were in the
grouping columns or elsewhere in the tlist, and it still doesn't
seem worth the trouble.  But this trivial change allows us to
recognize that "SELECT DISTINCT unnest(foo) FROM ..." produces
unique-ified output, which seems worth having.

Also, fix estimate_num_groups() to consider the possibility of SRFs in
the grouping columns.  Its failure to do so was masked before v10 because
grouping_planner() scaled up plan rowcount estimates by the estimated SRF
multiplier after performing grouping.  That doesn't happen anymore, which
is more correct, but it means we need an adjustment in the estimate for
the number of groups.  Failure to do this leads to an underestimate for
the number of output rows of subqueries like "SELECT DISTINCT unnest(foo)"
compared to what 9.6 and earlier estimated, thus breaking plan choices
in some cases.

Per report from Dmitry Shalashov.  Back-patch to v10 to avoid degraded
plan choices compared to previous releases.

Discussion: https://postgr.es/m/CAKPeCUGAeHgoh5O=SvcQxREVkoX7UdeJUMj1F5=aBNvoTa+O8w@mail.gmail.com

The comments in get_policies_for_relation() say that CREATE POLICY
does not support defining restrictive policies. This is no longer
true, starting from PG10.

This table summarizes which RLS policy expressions apply to each
command type, and whether they apply to the old or new tuples (or
both), which saves reading through a lot of text.

Rod Taylor, hacked on by me. Reviewed by Fabien Coelho.

Discussion: https://postgr.es/m/CAHz80e4HxJShm6m9ZWFrHW=pgd2KP=RZmfFnEccujtPMiAOW5Q@mail.gmail.com

The query didn't really have a preferred index, leading to platform-
specific choices of which one to use.  Adjust it to make sure tenk1_hundred
is always chosen.

Per buildfarm.

This is necessary for ActivePerl 5.18 onwards and for Strawberry Perl.
It is not sufficient for 32-bit builds with newer Visual Studio; these
fail with error LINK2026.  Back-patch to 9.3 (all supported versions).

Reported by Victor Wagner.

Discussion: https://postgr.es/m/20160326154321.7754ab8f@wagner.wagner.home

When strict aggregate combine functions, used in multi-stage/parallel
aggregation, returned NULL, we didn't check for that, invoking the
combine function with NULL the next round, despite it being strict.

The equivalent code invoking normal transition functions has a check
for that situation, which did not get copied in a7de3dc5. Fix the
bug by adding the equivalent check.

Based on a quick look I could not find any strict combine functions in
core actually returning NULL, and it doesn't seem very likely external
users have done so. So this isn't likely to have caused issues in
practice.

Add tests verifying transition / combine functions returning NULL is
tested.

Reported-By: Andres Freund
Author: Andres Freund
Discussion: https://postgr.es/m/20171121033642.7xvmjqrl4jdaaat3@alap3.anarazel.de
Backpatch: 9.6, where parallel aggregation was introduced

wal_receiver_timeout, wal_receiver_status_interval and
wal_retrieve_retry_interval configuration parameters affect the logical rep
worker, but previously only wal_receiver_status_interval was not mentioned
as such parameter in the doc.

Back-patch to v10 where logical rep was added.

Author: Masahiko Sawada
Discussion: https://www.postgresql.org/message-id/CAD21AoBUnuH_UsnKXyPCsCR7EAMamW0sSb6a7=WgiQRpnMAp5w@mail.gmail.com

This hack closes a race condition in "make -j check-world" and "make -j
installcheck-world".  Back-patch to v10, before which these parallel
invocations had worse problems.

Discussion: https://postgr.es/m/20171106080752.GA1298146@rfd.leadboat.com