Commit 25fff407 has granted execute permission of the function
pg_stat_statements_reset() to default role "pg_read_all_stats", but this
role is meant to read statistics, and not to reset them.  The
permissions on this function are revoked from "pg_read_all_stats".  The
version of pg_stat_statements is bumped up in consequence.

Author: Haribabu Kommi
Reviewed-by: Michael Paquier, Amit Kapila
Discussion: https://postgr.es/m/CAJrrPGf5fCnKqXObpwGN9nMyD--tzOf-7LFCJiz59Z1wJ5qj9A@mail.gmail.com

We haven't touched these since text search functionality landed in core
in 2007 :-(.  While the upstream project isn't a beehive of activity,
they do make additions and bug fixes from time to time.  Update our
copies of these files.

Also update our documentation about how to keep things in sync, since
they're not making distribution tarballs these days.  Fortunately,
their source code turns out to be a breeze to build.

Notable changes:

* The non-UTF8 version of the hungarian stemmer now works in LATIN2
not LATIN1.

* New stemmers have appeared for arabic, indonesian, irish, lithuanian,
nepali, and tamil.  These all work in UTF8, and the indonesian and
irish ones also work in LATIN1.

(There are some new stemmers that I did not incorporate, mainly because
their names don't match the underlying languages, suggesting that they're
not to be considered mainstream.)

Worth noting: the upstream Nepali dictionary was contributed by
Arthur Zakirov.

initdb forced because the contents of snowball_create.sql have
changed.

Still TODO: see about updating the stopword lists.

Arthur Zakirov, minor mods and doc work by me

Discussion: https://postgr.es/m/20180626122025.GA12647@zakirov.localdomain
Discussion: https://postgr.es/m/20180219140849.GA9050@zakirov.localdomain

Due to my (Andres') omission auto_explain did not include information
about JIT compilation. Fix that.

Author: Lukas Fittl
Discussion:
https://postgr.es/m/CAP53PkzgSyoTCau0-5FNaM484B=uO8nLzma7L1ncWLb1=oVJQA@mail.gmail.com
Backpatch: 11-, where JIT compilation was introduced

A discussion about also reporting JIT compilation overhead on workers
brought unhappiness with the verbosity of the current explain format
to light.  Make the text format more dense, and restructure the
structured output to mirror that more closely.

As we're re-jiggering the output format anyway: The denser format
allows us to report all flags for JIT compilation (now also reporting
PGJIT_EXPR and PGJIT_DEFORM), and report the total time in addition to
the individual times.

Per complaint from Tom Lane.

Author: Andres Freund
Discussion: https://postgr.es/m/27812.1537221015@sss.pgh.pa.us
Backpatch: 11-, where JIT compilation was introduced

Ensure that triggers get properly filled in tuples for the OLD value.
Also fix the logic of detecting missing null values. The previous logic
failed to detect a missing null column before the first missing column
with a default. Fixing this has simplified the logic a bit.

Regression tests are added to test changes. This should ensure better
coverage of expand_tuple().

Original bug reports, and some code and test scripts from Tomas Vondra

Backpatch to release 11.

Previously, pgbench always used select(2) for this purpose, but that's
problematic for very high client counts, because select() can't deal
with file descriptor numbers larger than FD_SETSIZE.  It's pretty common
for that to be only 1024 or so, whereas modern OSes can allow many more
open files than that.  Using poll(2) would surmount that problem, but it
creates another one: poll()'s timeout resolution is only 1ms, which is
poor enough to cause problems with --rate specifications approaching or
exceeding 1K TPS.

On platforms that have ppoll(2), which includes Linux and recent
FreeBSD, we can use that to avoid the FD_SETSIZE problem without any
loss of timeout resolution.  Hence, add configure logic to test for
ppoll(), and use it if available.

This patch introduces an abstraction layer into pgbench that could
be extended to support other kernel event-wait APIs such as kevents.
But actually adding such support is a matter for some future patch.

Doug Rady, reviewed by Robert Haas and Fabien Coelho, and whacked around
a good bit more by me

Discussion: https://postgr.es/m/23D017C9-81B7-484D-8490-FD94DEC4DF59@amazon.com

array_out overestimated the space needed for its output, possibly by
a very substantial amount if the array is multi-dimensional, because
of wrong order of operations in the loop that counts the number of
curly-brace pairs needed.  While the output string is normally
short-lived, this could still cause problems in extreme cases.

An additional minor error was that it counted one more delimiter than
is actually needed.

Repair those errors, add an Assert that the space is now correctly
calculated, and make some minor improvements in the comments.

I also failed to resist the temptation to get rid of an integer
modulus operation per array element; a simple comparison is sufficient.

This bug dates clear back to Berkeley days, so back-patch to all
supported versions.

Keiichi Hirobe, minor additional work by me

Discussion: https://postgr.es/m/CAH=EFxE9W0tRvQkixR2XJRRCToUYUEDkJZk6tnADXugPBRdcdg@mail.gmail.com

aclitem functions and operators have been heretofore undocumented.
Fix that. While at it, ensure the non-operator aclitem functions have
pg_description strings.

Does not seem worthwhile to back-patch.

Author: Fabien Coelho, with pg_description from John Naylor, and significant
refactoring and editorialization by me.
Reviewed by: Tom Lane
Discussion: https://postgr.es/m/flat/alpine.DEB.2.21.1808010825490.18204%40lancre

This removes a difference between the standard IsUnderPostmaster
execution environment and that of --boot and --single.  In a stand-alone
backend, "SELECT random()" always started at the same seed.

On a system capable of using posix shared memory, initdb could still
conclude "selecting dynamic shared memory implementation ... sysv".
Crashed --boot or --single postgres processes orphaned shared memory
objects having names that collided with the not-actually-random names
that initdb probed.  The sysv fallback appeared after ten crashes of
--boot or --single postgres.  Since --boot and --single are rare in
production use, systems used for PostgreSQL development are the
principal candidate to notice this symptom.

Back-patch to 9.3 (all supported versions).  PostgreSQL 9.4 introduced
dynamic shared memory, but 9.3 does share the "SELECT random()" problem.

Reviewed by Tom Lane and Kyotaro HORIGUCHI.

Discussion: https://postgr.es/m/20180915221546.GA3159382@rfd.leadboat.com

This isn't terribly safe, and making it so doesn't seem like a small
project, so for the moment just warn against it.

Discussion: https://postgr.es/m/13624.1535486019@sss.pgh.pa.us

In a case where we have multiple relation-scan nodes in a cursor plan,
such as a scan of an inheritance tree, it's possible to fetch from a
given scan node, then rewind the cursor and fetch some row from an
earlier scan node.  In such a case, execCurrent.c mistakenly thought
that the later scan node was still active, because ExecReScan hadn't
done anything to make it look not-active.  We'd get some sort of
failure in the case of a SeqScan node, because the node's scan tuple
slot would be pointing at a HeapTuple whose t_self gets reset to
invalid by heapam.c.  But it seems possible that for other relation
scan node types we'd actually return a valid tuple TID to the caller,
resulting in updating or deleting a tuple that shouldn't have been
considered current.  To fix, forcibly clear the ScanTupleSlot in
ExecScanReScan.

Another issue here, which seems only latent at the moment but could
easily become a live bug in future, is that rewinding a cursor does
not necessarily lead to *immediately* applying ExecReScan to every
scan-level node in the plan tree.  Upper-level nodes will think that
they can postpone that call if their child node is already marked
with chgParam flags.  I don't see a way for that to happen today in
a plan tree that's simple enough for execCurrent.c's search_plan_tree
to understand, but that's one heck of a fragile assumption.  So, add
some logic in search_plan_tree to detect chgParam flags being set on
nodes that it descended to/through, and assume that that means we
should consider lower scan nodes to be logically reset even if their
ReScan call hasn't actually happened yet.

Per bug #15395 from Matvey Arye.  This has been broken for a long time,
so back-patch to all supported branches.

Discussion: https://postgr.es/m/153764171023.14986.280404050547008575@wrigleys.postgresql.org

Single pg_atomic_exchange_u32() is expected to be faster than loop of
pg_atomic_compare_exchange_u32().  Also, it would be consistent with
clog group update code.

Discussion: https://postgr.es/m/CAPpHfdtxLsC-bqfxFcHswZ91OxXcZVNDBBVfg9tAWU0jvn1tQA%40mail.gmail.com
Reviewed-by: Amit Kapila

Being able to use a value that can be changed on a connection basis is
useful with clusters distributed geographically, and makes failure
detection more flexible.  A note is added in the documentation about the
use of "options" in primary_conninfo, which can be hard to grasp for
newcomers with the need of two single quotes when listing a set of
parameters.

Author: Tsunakawa Takayuki
Reviewed-by: Masahiko Sawada, Michael Paquier
Discussion: https://postgr.es/m/0A3221C70F24FB45833433255569204D1FAAD3AE@G01JPEXMBYT05

This replaces the "TailMatchesN" macros with just "TailMatches",
and likewise "HeadMatchesN" becomes "HeadMatches" and "MatchesN"
becomes "Matches".  The various COMPLETE_WITH_LISTn macros are
reduced to COMPLETE_WITH, and the single-item COMPLETE_WITH_CONST
also gets folded into that.  This eliminates a lot of minor
annoyance in writing tab-completion rules.  Usefully, the compiled
code also gets a bit smaller (10% or so, on my machine).

The implementation depends on variadic macros, so we couldn't have
done this before we required C99.

Andres Freund and Thomas Munro; some cosmetic cleanup by me.

Discussion: https://postgr.es/m/d8jo9djvm7h.fsf@dalvik.ping.uio.no

JIT was disabled by default in a PG 11 in a separate commit that will
normally not appear in the PG 12 git logs.  Therefore, create a PG 12
document and mention the fact that JIT is enabled by default in this
release.  (A similar change in parallelism was missed in a prior
release.)

Reported-by: Andres Freund

Discussion: https://postgr.es/m/20180922000554.qukbhhlagpnopvko@alap3.anarazel.de

Backpatch-through: head

standard_conforming_strings defaulted to 'on' in PG 9.1.
bytea_output defaulted to 'hex' in PG 9.0.

Reported-by: André Hänsel

Discussion: https://postgr.es/m/12e601d447ac$345994a0$9d0cbde0$@webkr.de

Backpatch-through: 9.3

You can't use "FOR TABLE" as a single Matches argument, because readline
will consider that input to be two words not one.  It's necessary to make
the pattern contain two arguments.

The case accidentally worked anyway because the words_after_create
test fired ... but only for the first such table name.

Noted by Edmund Horner, though this isn't exactly his proposed fix.
Backpatch to v10 where the faulty code came in.

Discussion: https://postgr.es/m/CAMyN-kDe=gBmHgxWwUUaXuwK+p+7g1vChR7foPHRDLE592nJPQ@mail.gmail.com

Previously, we made no attempt to provide tab completion in these
statements' optional parenthesized options lists.  This patch teaches
psql to do so.

To prevent the option completions from being offered after we've already
seen a complete parenthesized option list, it's necessary to improve
word_matches() so that it allows a wildcard '*' in the middle of an
alternative, not only at the end as formerly.  That requires only a
little more code than before, and it allows us to test for "incomplete
parenthesized options" with a test like

    else if (HeadMatches2("EXPLAIN", "(*") &&
             !HeadMatches2("EXPLAIN", "(*)"))

In addition, add some logic to offer column names in the context of
"ANALYZE tablename ( ...", and likewise for VACUUM.  This isn't real
complete; it won't offer column names again after a comma.  But it's
better than before, and it doesn't take much code.

Justin Pryzby, reviewed at various times by Álvaro Herrera, Arthur
Zakirov, and Edmund Horner; some additional fixups by me

Discussion: https://postgr.es/m/20180529000623.GA21896@telsasoft.com

The previous convention was to use names based on the set of relkinds being
selected for, which was not at all helpful for maintenance, especially
since people had been quite inconsistent about whether to change the names
when they changed the relkinds being selected for.  Instead, use names
based on the functionality we need the relation to have, following the
model established by Query_for_list_of_updatables.

While at it, sort the list of Query constants a bit better; it had the
distinct air of code-assembled-by-dartboard before.

Discussion: https://postgr.es/m/14830.1537481254@sss.pgh.pa.us

Takeshi Ideriha complained that there is a mixture of Size and size_t
in dsa.c and corresponding header.  Let's use size_t.  Back-patch to 10
where dsa.c landed, to make future back-patching easy.

Discussion: https://postgr.es/m/4E72940DA2BF16479384A86D54D0988A6F19ABD9%40G01JPEXMBKW04

This can happen for CREATE TABLE and ALTER TABLE, so a mention is added
to both of them in the concerned subsections.

Author: Adrien Nayrat
Discussion: https://postgr.es/m/c4e8af11-1dfc-766a-c953-76979b9fcdaa@anayrat.info

As clang currently doesn't support -fexcess-precision=standard,
compiling x86-32 code with SSE2 disabled, can lead to problems with
floating point overflow checks and the like.

This issue was noticed because clang, on at least some BSDs, defaults
to i386 compatibility, whereas it defaults to pentium4 on Linux.  Our
forced usage of __builtin_isinf() lead to some overflow checks not
triggering when compiling for i386, e.g. when the result of the
calculation didn't overflow in 80bit registers, but did so in 64bit.

While we could just fall back to a non-builtin isinf, it seems likely
that the use of 80bit registers leads to other problems (which is why
we force the flag for GCC already).  Therefore error out when
detecting clang in that situation.

Reported-By: Victor Wagner
Analyzed-By: Andrew Gierth and Andres Freund
Author: Andres Freund
Discussion: https://postgr.es/m/20180905005130.ewk4xcs5dgyzcy45@alap3.anarazel.de
Backpatch: 9.3-, all supported versions are affected

40cfe860 enforces the translation mode to text for all frontends, so this
special handling in initdb is not needed anymore.

This should offer the same relation types that SELECT ... FROM would.
You can't select from an index for instance, so offering it here is
unhelpful.  Noted while testing ilmari's recent patch.

We have the infrastructure to offer a list of tablespace names, but
it wasn't being used here; instead you got "FROM", "CURRENT", and "TO"
which aren't actually legal in this syntax.

Dagfinn Ilmari Mannsåker, reviewed by Arthur Zakirov

Discussion: https://postgr.es/m/d8jo9djvm7h.fsf@dalvik.ping.uio.no

Per buildfarm member crake.

I noticed that all non-composite, non-array entries in pg_type.dat
had descr strings, except for "json" and the pseudo-types.  The
lack for json seems certainly an oversight, and there's surely
little reason to not have entries for the pseudo-types either.
So add some.

"make reformat-dat-files" turned up some formatting issues in
pg_amop.dat, too, so fix those in passing.

No catversion bump since the backend doesn't care too much what is
in pg_description.

This eliminates some more tedium in adding new catalog entries,
specifically the need to set up an array type when adding a new
built-in data type.  Now it's sufficient to assign an OID for the
array type and write it in an "array_type_oid" metadata field.
You don't have to fill the base type's typarray link explicitly, either.

No catversion bump since the contents of pg_type aren't changed.
(Well, their order might be different, but that doesn't matter.)

John Naylor, reviewed and whacked around a bit by
Dagfinn Ilmari Mannsåker, and some more by me.

Discussion: https://postgr.es/m/CAJVSVGVTb6m9pJF49b3SuA8J+T-THO9c0hxOmoyv-yGKh-FbNg@mail.gmail.com

cf984672 introduced improvement of handling of spaces and separators in
to_timestamp()/to_date() functions.  In particular, now we're skipping spaces
both before and after fields.  That may cause format string text character to
consume part of field in the situations, when it didn't happen before cf984672.
This commit cause format string text character consume input string characters
only when since previous field (or string beginning) number of skipped input
string characters is not greater than number of corresponding format string
characters (that is we didn't skip any extra characters in input string).

If a segment has been freed by dsa.c because it is entirely empty, other
backends must make sure to unmap it before following links to new
segments that might happen to have the same index number, or they could
finish up looking at a defunct segment and then corrupt the segment_bins
lists.  The correct protocol requires checking freed_segment_counter
after acquiring the area lock and before resolving any index number to a
segment.  Add the missing checks and an assertion.

Back-patch to 10, where dsa.c first arrived.

Author: Thomas Munro
Reported-by: Tomas Vondra
Discussion: https://postgr.es/m/CAEepm%3D0thg%2Bja5zGVa7jBy-uqyHrTqTm8HGhEOtMmigGrAqTbw%40mail.gmail.com

Several users of extensions complained of crashes in parallel workers
that turned out to be due to syscache access from their _PG_init()
functions.  Reorder the initialization of parallel workers so that
libraries are restored after the caches are initialized, and inside a
transaction.

This was reported in bug #15350 and elsewhere.  We don't consider it
to be a bug: extensions shouldn't do that, because then they can't be
used in shared_preload_libraries.  However, it's a fairly obscure
hazard and these extensions worked in practice before parallel query
came along.  So let's make it work.  Later commits might add a warning
message and eventually an error.

Back-patch to 9.6, where parallel query landed.

Author: Thomas Munro
Reviewed-by: Amit Kapila
Reported-by: Kieran McCusker, Jimmy
Discussion: https://postgr.es/m/153512195228.1489.8545997741965926448%40wrigleys.postgresql.org

Allowing frontends to use concurrent-safe open() and fopen() via 0ba06e0b
has the side-effect of switching the default translation mode from text
to binary, so the switch can cause breakages for frontend tools when the
caller of those new versions specifies neither binary and text.  This
commit makes sure to maintain strict compatibility with past versions,
so as no frontends should see a difference when upgrading.

Author: Laurenz Albe
Reviewed-by: Michael Paquier, Tom Lane
Discussion: https://postgr.es/m/20180917140202.GF31460@paquier.xyz

No periods at the ends of primary error messages, please.

Daniel Gustafsson

Discussion: https://postgr.es/m/43E004C0-18C6-42B4-A313-003B43EB0571@yesql.se

Commit 37c54863 removed the code in StandbyAcquireAccessExclusiveLock
that checked the return value of LockAcquireExtended.  That created a
bug, because it's still passing reportMemoryError = false to
LockAcquireExtended, meaning that LOCKACQUIRE_NOT_AVAIL will be returned
if we're out of shared memory for the lock table.

In such a situation, the startup process would believe it had acquired an
exclusive lock even though it hadn't, with potentially dire consequences.

To fix, just drop the use of reportMemoryError = false, which allows us
to simplify the call into a plain LockAcquire().  It's unclear that the
locktable-full situation arises often enough that it's worth having a
better recovery method than crash-and-restart.  (I strongly suspect that
the only reason the code path existed at all was that it was relatively
simple to do in the pre-37c54863 implementation.  But now it's not.)

LockAcquireExtended's reportMemoryError parameter is now dead code and
could be removed.  I refrained from doing so, however, because there
was some interest in resurrecting the behavior if we do get reports of
locktable-full failures in the field.  Also, it seems unwise to remove
the parameter concurrently with shipping commit f868a814, which added a
parameter; if there are any third-party callers of LockAcquireExtended,
we want them to get a wrong-number-of-parameters compile error rather
than a possibly-silent misinterpretation of its last parameter.

Back-patch to 9.6 where the bug was introduced.

Discussion: https://postgr.es/m/6202.1536359835@sss.pgh.pa.us

Currently, KNN searches were supported only by GiST.  SP-GiST also capable to
support them.  This commit implements that support.  SP-GiST scan stack is
replaced with queue, which serves as stack if no ordering is specified.  KNN
support is provided for three SP-GIST opclasses: quad_point_ops, kd_point_ops
and poly_ops (catversion is bumped).  Some common parts between GiST and SP-GiST
KNNs are extracted into separate functions.

Discussion: https://postgr.es/m/570825e8-47d0-4732-2bf6-88d67d2d51c8%40postgrespro.ru
Author: Nikita Glukhov, Alexander Korotkov based on GSoC work by Vlad Sterzhanov
Review: Andrey Borodin, Alexander Korotkov

In the normal course of operation, query trees will be serialized only if
they are stored as views or rules; and plan trees will be serialized only
if they get passed to parallel-query workers.  This leaves an awful lot of
opportunity for bugs/oversights to not get detected, as indeed we've just
been reminded of the hard way.

To improve matters, this patch adds a new compile option
WRITE_READ_PARSE_PLAN_TREES, which is modeled on the longstanding option
COPY_PARSE_PLAN_TREES; but instead of passing all parse and plan trees
through copyObject, it passes them through nodeToString + stringToNode.
Enabling this option in a buildfarm animal or two will catch problems
at least for cases that are exercised by the regression tests.

A small problem with this idea is that readfuncs.c historically has
discarded location fields, on the reasonable grounds that parse
locations in a retrieved view are not relevant to the current query.
But doing that in WRITE_READ_PARSE_PLAN_TREES breaks pg_stat_statements,
and it could cause problems for future improvements that might try to
report error locations at runtime.  To fix that, provide a variant
behavior in readfuncs.c that makes it restore location fields when
told to.

In passing, const-ify the string arguments of stringToNode and its
subsidiary functions, just because it annoyed me that they weren't
const already.

Discussion: https://postgr.es/m/17114.1537138992@sss.pgh.pa.us

A test patch to pass parse and plan trees through outfuncs + readfuncs
exposed several issues that need to be fixed to get clean matches:

Query.withCheckOptions failed to get copied; it's intentionally ignored
by outfuncs/readfuncs on the grounds that it'd always be NIL anyway in
stored rules.  This seems less than future-proof, and it's not even
saving very much, so just undo the decision and treat the field like
all others.

Several places that convert a view RTE into a subquery RTE, or similar
manipulations, failed to clear out fields that were specific to the
original RTE type and should be zero in a subquery RTE.  Since readfuncs.c
will leave such fields as zero, equalfuncs.c thinks the nodes are different
leading to a reported mismatch.  It seems like a good idea to clear out the
no-longer-needed fields, even though in principle nothing should look at
them; the node ought to be indistinguishable from how it would look if
we'd built a new node instead of scribbling on the old one.

BuildOnConflictExcludedTargetlist randomly set the resname of some
TargetEntries to "" not NULL.  outfuncs/readfuncs don't distinguish those
cases, and so the string will read back in as NULL ... but equalfuncs.c
does distinguish.  Perhaps we ought to try to make things more consistent
in this area --- but it's just useless extra code space for
BuildOnConflictExcludedTargetlist to not use NULL here, so I fixed it for
now by making it do that.

catversion bumped because the change in handling of Query.withCheckOptions
affects stored rules.

Discussion: https://postgr.es/m/17114.1537138992@sss.pgh.pa.us

The system expects TABLEFUNC RTEs to have coltypes, coltypmods, and
colcollations lists, but outfuncs doesn't dump them and readfuncs doesn't
restore them.  This doesn't cause obvious failures, because the only things
that look at those fields are expandRTE() and get_rte_attribute_type(),
which are mostly used during parse analysis, before anything would've
passed the parsetree through outfuncs/readfuncs.  But expandRTE() is used
in build_physical_tlist(), which means that that function will return a
wrong answer for a TABLEFUNC RTE that came from a view.  Very accidentally,
this doesn't cause serious problems, because what it will return is NIL
which callers will interpret as "couldn't build a physical tlist because
of dropped columns".  So you still get a plan that works, though it's
marginally less efficient than it could be.  There are also some other
expandRTE() calls associated with transformation of whole-row Vars in
the planner.  I have been unable to exhibit misbehavior from that, and
it may be unreachable in any case that anyone would care about ... but
I'm not entirely convinced, so this seems like something we should back-
patch a fix for.  Fortunately, we can fix it without forcing a change
of stored rules and a catversion bump, because we can just copy these
lists from the subsidiary TableFunc object.

readfuncs.c was also missing support for NamedTuplestoreScan plan nodes.
This accidentally fails to break parallel query because a query using
a named tuplestore would never be considered parallel-safe anyway.
However, project policy since parallel query came in is that all plan
node types should have outfuncs/readfuncs support, so this is clearly
an oversight that should be repaired.

Noted while fooling around with a patch to test outfuncs/readfuncs more
thoroughly.  That exposed some other issues too, but these are the only
ones that seem worth back-patching.

Back-patch to v10 where both of these features came in.

Discussion: https://postgr.es/m/17114.1537138992@sss.pgh.pa.us

Chris Travers reported that the startup process can repeatedly try to
cancel a backend that is in a posix_fallocate()/EINTR loop and cause it
to loop forever.  Teach the retry loop to give up if an interrupt is
pending.  Don't actually check for interrupts in that loop though,
because a non-local exit would skip some clean-up code in the caller.

Back-patch to 9.4 where DSM was added (and posix_fallocate() was later
back-patched).

Author: Chris Travers
Reviewed-by: Ildar Musin, Murat Kabilov, Oleksii Kliukin
Tested-by: Oleksii Kliukin
Discussion: https://postgr.es/m/CAN-RpxB-oeZve_J3SM_6%3DHXPmvEG%3DHX%2B9V9pi8g2YR7YW0rBBg%40mail.gmail.com

Those routines gain a missing_ok argument, allowing a caller to get a
NULL result instead of an error if set to true.  This is part of a
larger refactoring effort for objectaddress.c where trying to check for
non-existing objects does not result in cache lookup failures.

Author: Michael Paquier
Reviewed-by: Aleksander Alekseev, Álvaro Herrera
Discussion: https://postgr.es/m/CAB7nPqSZxrSmdHK-rny7z8mi=EAFXJ5J-0RbzDw6aus=wB5azQ@mail.gmail.com