Adjust the struct comment that describes how page splits use their
descent stack to cascade up the tree from the leaf level.

In passing, fix up some unrelated nbtree comments that had typos or were
obsolete.

crypt() hasn't been needed since crypt detection was removed from
PostgreSQL, so these configure checks are not necessary.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/21f88934-f00c-27f6-a9d8-7ea06d317781%402ndquadrant.com

In early development patches, "replication origins" were called "identifiers";
almost everything was renamed, but these references to the old terminology
went unnoticed.

Reported-by: Craig Ringer

Using pg_pltemplate as test data was probably not very forward-looking,
considering we've had many discussions around removing that catalog
altogether.  Use a nearby temp table instead, to make these two test
scripts more self-contained.  This is a better test case anyway, since
it exercises the scenario where the entries in the anyarray column
actually vary in type intra-query.

Author: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Discussion: https://www.postgresql.org/message-id/flat/E393EC88-377F-4C59-A67A-69F2A38D17C7@yesql.se

Correct the comment for read_any_attr().  Give a clearer error message
when parsing at the end of the string, when the client-final-message
does not contain a "p" attribute (for some reason).
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://www.postgresql.org/message-id/flat/2fb8a15b-de35-682d-a77b-edcc9c52fa12%402ndquadrant.com

Author: Alexander Lakhin
Discussion: https://postgr.es/m/20190819072244.GE18166@paquier.xyz

FD_SETSIZE is included in sys/select.h per POSIX, and this header
inclusion has been moved to scripts_parallel.c as of 5f384037 without
moving the variable, causing a compilation failure on recent versions of
OpenBSD (6.6 was the version used in the report).

In order to take care of the failure, move FD_SETSIZE directly to
scripts_parallel.c with a wrapper controlling the maximum number of
parallel slots supported, based on a suggestion by Andres Freund.

While on it, reduce the maximum number to be less than FD_SETSIZE,
leaving some room for stdin, stdout and such as they consume some file
descriptors.

The buildfarm did not complain about that, as it happens to only be
an issue on recent versions of OpenBSD and there is no coverage in this
area.  51c3e9fa fixed a similar set of issues.

Bug: #15964
Reported-by: Sean Farrell
Discussion: https://postgr.es/m/15964-c1753bdfed722e04@postgresql.org

This has been found during its translation.

Author: Liudmila Mantrova
Discussion: https://postgr.es/m/CAEkD-mDJHV3bhgezu3MUafJLoAKsOOT86+wHukKU8_NeiJYhLQ@mail.gmail.com
Backpatch-through: 12

If the record argument is NULL and has no declared type more concrete
than RECORD, we can't extract useful information about the desired
rowtype from it.  In this case, see if we're in FROM with an AS clause,
and if so extract the needed rowtype info from AS.

It worked like this before v11, but commit 37a795a6 removed the
behavior, reasoning that it was undocumented, inefficient, and utterly
not self-consistent.  If you want to take type info from an AS clause,
you should be using the json_to_record() family of functions not the
json_populate_record() family.  Also, it was already the case that
the "populate" functions would fail for a null-valued RECORD input
(with an unfriendly "record type has not been registered" error)
when there wasn't an AS clause at hand, and it wasn't obvious that
that behavior wasn't OK when there was one.  However, it emerges
that some people were depending on this to work, and indeed the
rather off-point error message you got if you left off AS encouraged
slapping on AS without switching to the json_to_record() family.

Hence, put back the fallback behavior of looking for AS.  While at it,
improve the run-time error you get when there's no place to obtain type
info; we can do a lot better than "record type has not been registered".
(We can't, unfortunately, easily improve the parse-time error message
that leads people down this path in the first place.)

While at it, I refactored the code a bit to avoid duplicating the
same logic in several different places.

Per bug #15940 from Jaroslav Sivy.  Back-patch to v11 where the
current coding came in.  (The pre-v11 deficiencies in this area
aren't regressions, so we'll leave those branches alone.)

Patch by me, based on preliminary analysis by Dmitry Dolgov.

Discussion: https://postgr.es/m/15940-2ab76dc58ffb85b6@postgresql.org

Necessary after fb3b098f. That previously escaped notice, because all
including sites already include fmgr.h some other way.

Reported-By: Tom Lane
Author: Andres Freund
Discussion: https://postgr.es/m/17463.1566153454@sss.pgh.pa.us

We already had "cpluspluscheck", which served the dual purposes of
verifying that headers compile standalone and that they compile as C++.
However, C++ compilers don't have the exact same set of error conditions
as C compilers, so this doesn't really prove that a header will compile
standalone as C.

Hence, add a second script that's largely similar but runs the C
compiler not C++.

Also add a bit more documentation than the none-at-all we had before.

Discussion: https://postgr.es/m/14803.1566175851@sss.pgh.pa.us

IANA tzcode release 2019b adds an option that tells zic not to emit
the old 32-bit section of the timezone files, and to skip some other
space-wasting hacks needed for compatibility with old timezone client
libraries.  Since we only expect our own code to use the timezone data
we install, and our code is up-to-date with 2019b, there's no apparent
reason not to generate the smallest possible files.

Unfortunately, while the individual zone files do get significantly
smaller in many cases, they were not that big to begin with; which
means that no real space savings ensues on filesystems that don't
optimize small files.  (For instance, on ext4 with 4K block size,
"du" says the installed timezone tree is the same size as before.)
Still, it seems worth making the change, if only because this is
presumably the wave of the future.  At the very least, we'll save
some cycles while reading a zone file.

But given the marginal value and the fact that this is a new code
path, it doesn't seem worth the risk of back-patching this change
into stable branches.  Hence, unlike most of our timezone-related
changes, apply to HEAD only.

Discussion: https://postgr.es/m/24998.1563403327@sss.pgh.pa.us

Author: Jürgen Purtz
Discussion: https://postgr.es/m/c6027f7a-78ea-8453-0837-09903ba5fd9b@purtz.de

In a vpath build, we need to point to the source directory to allow
FOP to find the images.

Oversight in 7bdc6556.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/5da8e325-c665-da95-21e0-c8a99ea61fbf@gmail.com

This fixes various typos in docs and comments, and removes some orphaned
definitions.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/5da8e325-c665-da95-21e0-c8a99ea61fbf@gmail.com

Prefix inet_net_ntop and sibling routines with "pg_" to ensure that
they aren't mistaken for C-library functions.  This fixes warnings
from cpluspluscheck on some platforms, and should help reduce reader
confusion everywhere, since our functions aren't exactly interchangeable
with the library versions (they may have different ideas about address
family codes).

This shouldn't be fixing any actual bugs, unless somebody's linker
is misbehaving, so no need to back-patch.

Discussion: https://postgr.es/m/20518.1559494394@sss.pgh.pa.us

Remove use of "register" keyword in hashfn.c.  It's obsolescent
according to recent C++ compilers, and no modern C compiler pays
much attention to it either.

Also fix one cosmetic warning about signed vs unsigned comparison.

Discussion: https://postgr.es/m/20518.1559494394@sss.pgh.pa.us

Needs libpq-fe.h for references to PGConn.

Discussion: https://postgr.es/m/17463.1566153454@sss.pgh.pa.us

This has to have <time.h>, or the references to "struct tm" don't
mean what they should.

We have some other recently-introduced issues of the same ilk,
but this one seems old.  No backpatch though, as it's only a
latent problem for most purposes.

If a table inherits from multiple unrelated parents, we must disallow
changing the type of a column inherited from multiple such parents, else
it would be out of step with the other parents.  However, it's possible
for the column to ultimately be inherited from just one common ancestor,
in which case a change starting from that ancestor should still be
allowed.  (I would not be excited about preserving that option, were
it not that we have regression test cases exercising it already ...)

It's slightly annoying that this patch looks different from the logic
with the same end goal in renameatt(), and more annoying that it
requires an extra syscache lookup to make the test.  However, the
recursion logic is quite different in the two functions, and a
back-patched bug fix is no place to be trying to unify them.

Per report from Manuel Rigger.  Back-patch to 9.5.  The bug exists in
9.4 too (and doubtless much further back); but the way the recursion
is done in 9.4 is a good bit different, so that substantial refactoring
would be needed to fix it in 9.4.  I'm disinclined to do that, or risk
introducing new bugs, for a bug that has escaped notice for this long.

Discussion: https://postgr.es/m/CA+u7OA4qogDv9rz1HAb-ADxttXYPqQdUdPY_yd4kCzywNxRQXA@mail.gmail.com

This test failed fairly reproducibly on some CLOBBER_CACHE_ALWAYS
buildfarm animals.  The cause seems to be that if a parallel worker
is slow enough to reach its lock wait, it may not be released by
the first deadlock check run, and then later deadlock checks might
decide to unblock the d2 session instead of the d1 session, leaving
us in an undetected deadlock state (since the isolationtester client
is waiting for d1 to complete first).

Fix by introducing an additional lock wait at the end of the d2a1
step, ensuring that the deadlock checker will recognize that d1
has to be unblocked before d2a1 completes.

Also reduce max_parallel_workers_per_gather to 3 in this test.  With the
default max_worker_processes value, we were only getting one parallel
worker for the d2a1 step, which is not the case I hoped to test.  We
should get 3 for d1a2 and 2 for d2a1, as the code stands; and maybe 3
for d2a1 if somebody figures out why the last parallel worker slot isn't
free already.

Discussion: https://postgr.es/m/22195.1566077308@sss.pgh.pa.us

If an assertion expression contained a macro, the failed assertion
message would print the expanded macro, which is usually unhelpful and
confusing.  Restructure the Assert macros to not expand any macros
when constructing the failure message.

This also fixes that the existing output for Assert et al. shows
the *inverted* condition, which is also confusing and not how
assertions usually work.

Discussion: https://www.postgresql.org/message-id/flat/6c68efe3-117a-dcc1-73d4-18ba1ec532e2%402ndquadrant.com

Reported-By: Heikki Linnakangas
Author: Michael Paquier
Discussion: https://postgr.es/m/d6ffbebb-a0d2-181c-811d-b029b2225ed7@iki.fi
Backpatch: 12-, where pluggable table access methods were introduced

Most of the fmgr.h includes were obsoleted by 352a24a1. A
few others can be obsoleted using the underlying struct type in an
implementation detail.

Author: Andres Freund
Discussion: https://postgr.es/m/20190803193733.g3l3x3o42uv4qj7l@alap3.anarazel.de

For most uses of acl.h the details of how "Acl" internally looks like
are irrelevant. It might make sense to move a lot of the
implementation details into a separate header at a later point.

The main motivation of this change is to avoid including fmgr.h (via
array.h, which needs it for exposed structs) in a lot of files that
otherwise don't need it. A subsequent commit will remove the fmgr.h
include from a lot of files.

Directly include utils/array.h and utils/expandeddatum.h from the
files that need them, but previously included them indirectly, via
acl.h.

Author: Andres Freund
Discussion: https://postgr.es/m/20190803193733.g3l3x3o42uv4qj7l@alap3.anarazel.de

These aren't needed after 352a24a1. The remaining prototypes are
not defined on the SQL level.

Author: Andres Freund
Discussion: https://postgr.es/m/20190803193733.g3l3x3o42uv4qj7l@alap3.anarazel.de

These seem to be leftovers from the original partitionwise-join patch,
perhaps.

Discussion: https://postgr.es/m/CAPmGK145YiMTPRnvev1dLz8na_-0aZ=Xyqn8f2QsJFBUTObNow@mail.gmail.com

This is a variant of the problem fixed in commit 25b69256, which
unfortunately we failed to detect at the time.  If an update trigger
returns the "old" tuple, as it's entitled to do, then a subsequent
iteration of the loop in ExecBRUpdateTriggers would have "oldtuple"
equal to "trigtuple" and would fail to notice that it shouldn't
free that.

In addition to fixing the code, extend the test case added by
25b69256 so that it covers multiple-trigger-iterations cases.

This problem does not manifest in v12/HEAD, as a result of the
relevant code having been largely rewritten for slotification.
However, include the test case into v12/HEAD anyway, since this
is clearly an area that someone could break again in future.

Per report from Piotr Gabriel Kosinski.  Back-patch into all
supported branches, since the bug seems quite old.

Diagnosis and code fix by Thomas Munro, test case by me.

Discussion: https://postgr.es/m/CAFMLSdP0rd7LqC3j-H6Fh51FYSt5A10DDh-3=W4PPc4LLUQ8YQ@mail.gmail.com

Commit 4b93f579 rearranged things in plpgsql to make it cope better with
composite types changing underneath it intra-session.  However, I failed to
consider the case of a composite type being dropped and recreated entirely.
In my defense, the previous coding didn't consider that possibility at all
either --- but it would accidentally work so long as you didn't change the
type's field list, because the built-at-compile-time list of component
variables would then still match the type's new definition.  The new
coding, however, occasionally tries to re-look-up the type by OID, and
then fails to find the dropped type.

To fix this, we need to save the TypeName struct, and then redo the type
OID lookup from that.  Of course that's expensive, so we don't want to do
it every time we need the type OID.  This can be fixed in the same way that
4b93f579 dealt with changes to composite types' definitions: keep an eye
on the type's typcache entry to see if its tupledesc has been invalidated.
(Perhaps, at some point, this mechanism should be generalized so it can
work for non-composite types too; but for now, plpgsql only tries to
cope with intra-session redefinitions of composites.)

I'm slightly hesitant to back-patch this into v11, because it changes
the contents of struct PLpgSQL_type as well as the signature of
plpgsql_build_datatype(), so in principle it could break code that is
poking into the innards of plpgsql.  However, the only popular extension
of that ilk is pldebugger, and it doesn't seem to be affected.  Since
this is a regression for people who were relying on the old behavior,
it seems worth taking the small risk of causing compatibility issues.

Per bug #15913 from Daniel Fiori.  Back-patch to v11 where 4b93f579
came in.

Discussion: https://postgr.es/m/15913-a7e112e16dedcffc@postgresql.org

Previously, async.c got rid of duplicate notifications by scanning
the list of pending events to compare each one to the proposed new
event.  This works okay for very small numbers of distinct events,
but degrades as O(N^2) for many events.  We can improve matters by
using a hash table to probe for duplicates.  So as not to add a
lot of overhead for the simple cases that the code did handle well
before, create the hash table only once a (sub)transaction has
queued more than 16 distinct notify events.

A downside is that we now have to do per-event work to propagate
a successful subtransaction's notify events up to its parent.
(But this isn't significant unless the subtransaction had many
events, in which case the O(N^2) behavior would have been in
play already, so we still come out ahead.)

We can make some lemonade out of this lemon, though: since we must
examine each event anyway, it's now possible to de-duplicate events
fully, rather than skipping that for events merged up from
subtransactions.  Hence, remove the old weasel wording in notify.sgml
about whether de-duplication happens or not, and adjust the test
case in async-notify.spec that exhibited the old behavior.

While at it, rearrange the definition of struct Notification to make
it more compact and require just one palloc per event, rather than
two or three.  This saves space when there are a lot of events,
in fact more than enough to buy back the space needed for the hash
table.

Patch by me, based on discussions around a different patch
submitted by Filip Rembiałkowski.

Discussion: https://postgr.es/m/17822.1564186806@sss.pgh.pa.us

Clarify what external tools can do to this file, and add a bit
of detail about what ALTER SYSTEM itself does.

Discussion: https://postgr.es/m/aed6cc9f-98f3-2693-ac81-52bb0052307e@2ndquadrant.com

ALTER SYSTEM itself normally won't make duplicate entries (although
up till this patch, it was possible to confuse it by writing case
variants of a GUC's name).  However, if some external tool has appended
entries to the file, that could result in duplicate entries for a single
GUC name.  In such a situation, ALTER SYSTEM did exactly the wrong thing,
because it replaced or removed only the first matching entry, leaving
the later one(s) still there and hence still determining the active value.

This patch fixes that by making ALTER SYSTEM sweep through the file and
remove all matching entries, then (if not ALTER SYSTEM RESET) append the
new setting to the end.  This means entries will be in order of last
setting rather than first setting, but that shouldn't hurt anything.

Also, make the comparisons case-insensitive so that the right things
happen if you do, say, ALTER SYSTEM SET "TimeZone" = 'whatever'.

This has been broken since ALTER SYSTEM was invented, so back-patch
to all supported branches.

Ian Barwick, with minor mods by me

Discussion: https://postgr.es/m/aed6cc9f-98f3-2693-ac81-52bb0052307e@2ndquadrant.com

The initial value of the nbtree stack downlink block number field
recorded during an initial descent of the tree wasn't actually used.
Both _bt_getstackbuf() callers overwrote the value with their own value.

Remove the block number field from the stack struct, and add a child
block number argument to _bt_getstackbuf() in its place.  This makes the
overall design of _bt_getstackbuf() clearer.

Author: Peter Geoghegan
Reviewed-By: Anastasia Lubennikova
Discussion: https://postgr.es/m/CAH2-Wzmx+UbXt2YNOUCZ-a04VdXU=S=OHuAuD7Z8uQq-PXTYUg@mail.gmail.com

The method of passing LC_COLLATE and LC_CTYPE to the backend during
initdb is obsolete as of 61d96749.
This can all be removed.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/eeaf2f99-a1a6-8aca-3f43-9ab0b2fb112a%402ndquadrant.com

This is a fix similar to 2d7d67cc, where slight plan alteration can
cause a random failure of this regression test because of an incorect
tuple ordering, except that this one involves lookups of pg_type.
Similarly to the other case, add ORDER BY clauses to ensure the output
order.

The failure has been seen at least once on buildfarm member skink.

Reported-by: Thomas Munro
Discussion: https://postgr.es/m/CA+hUKGLjR9ZBvhXcr9b-NSBHPw9aRgbjyzGE+kqLsT4vwX+nkQ@mail.gmail.com
Backpatch-through: 12

Commit d2086b08 removed almost all cases where nbtree must release a
read buffer lock and acquire a write buffer lock instead, so remaining
cases in which that's still necessary are not notable enough to appear
in the nbtree README.

More importantly, holding on to a buffer pin in cases where nbtree must
trade a read lock for a write lock is very unlikely to save any I/O.
This seems to have been a long overlooked throwback to a time when
nbtree cared about write-ordering dependencies, and performed
synchronous buffer writes.  It hasn't worked that way in many years.