You can use this to view the contents of the time to XID mapping
which the server maintains when old_snapshot_threshold != -1.
Being able to view that information may be interesting for users,
and it's definitely useful for figuring out whether the mapping
is being maintained correctly. It isn't, so that will need to be
fixed in a subsequent commit.

Patch by me, reviewed by Thomas Munro, Dilip Kumar, Hamid Akhtar.

Discussion: http://postgr.es/m/CA+TgmoY=aqf0zjTD+3dUWYkgMiNDegDLFjo+6ze=Wtpik+3XqA@mail.gmail.com

This makes it possible for code outside snapmgr.c to examine the
contents of this data structure. This commit does not add any code
which actually does so; a subsequent commit will make that change.

Patch by me, reviewed by Thomas Munro, Dilip Kumar, Hamid Akhtar.

Discussion: http://postgr.es/m/CA+TgmoY=aqf0zjTD+3dUWYkgMiNDegDLFjo+6ze=Wtpik+3XqA@mail.gmail.com

Zhijie Hou

Discussion: https://postgr.es/m/ce2cd951fe9b448a9cda99dc1a871fb9@G08CNEXMBPEKD05.g08.fujitsu.local

Commit fbeb9da2, which added the tsearch_readline APIs, left
t_readline() in place as a compatibility measure.  But that function
has been unused and deprecated for twelve years now, so that seems
like enough time to remove it.  Doing so, and merging t_readline's
code into tsearch_readline, aids in making several useful
improvements:

* The hard-wired 4K limit on line length in tsearch data files is
removed, by using a StringInfo buffer instead of a fixed-size buffer.

* We can buy back the per-line palloc/pfree added by 3ea7e955
in the common case where encoding conversion is not required.

* We no longer need a separate pg_verify_mbstr call, as that
functionality was folded into encoding conversion some time ago.

(We could have done some of this stuff while keeping t_readline as a
separate API, but there seems little point, since there's no reason
for anyone to still be using t_readline directly.)

Discussion: https://postgr.es/m/48A4FA71-524E-41B9-953A-FD04EF36E2E7@yesql.se

Harmonize behavior by moving reponsibility for fsyncing directories down
into slru.c.  In 10 and later, only the multixact directories were
missed (see commit 1b02be21), and in older branches all SLRUs were
missed.

Back-patch to all supported releases.
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CA%2BhUKGLtsTUOScnNoSMZ-2ZLv%2BwGh01J6kAo_DM8mTRq1sKdSQ%40mail.gmail.com

We failed to pass down the query string to check_new_partition_bound,
so that its attempts to provide error cursor positions were for naught;
one must have the query string to get parser_errposition to do anything.
Adjust its API to require a ParseState to be passed down.

Also, improve the logic inside check_new_partition_bound so that the
cursor points at the partition bound for the specific column causing
the issue, when one can be identified.

That part is also for naught if we can't determine the query position of
the column with the problem.  Improve transformPartitionBoundValue so
that it makes sure that const-simplified partition expressions will be
properly labeled with positions.  In passing, skip calling evaluate_expr
if the value is already a Const, which is surely the most common case.

Alexandra Wang, Ashwin Agrawal, Amit Langote; reviewed by Ashutosh Bapat

Discussion: https://postgr.es/m/CACiyaSopZoqssfMzgHk6fAkp01cL6vnqBdmTw2C5_KJaFR_aMg@mail.gmail.com
Discussion: https://postgr.es/m/CAJV4CdrZ5mKuaEsRSbLf2URQ3h6iMtKD=hik8MaF5WwdmC9uZw@mail.gmail.com

tsearch_readline() saves the string pointer it returns to the caller
for possible use in the associated error context callback.  However,
the caller will usually pfree that string sometime before it next
calls tsearch_readline(), so that there is a window where an ereport
will try to print an already-freed string.

The built-in users of tsearch_readline() happen to all do that pfree
at the bottoms of their loops, so that the window is effectively
empty for them.  However, this is not documented as a requirement,
and contrib/dict_xsyn doesn't do it like that, so it seems likely
that third-party dictionaries might have live bugs here.

The practical consequences of this seem pretty limited in any case,
since production builds wouldn't clobber the freed string immediately,
besides which you'd not expect syntax errors in dictionary files
being used in production.  Still, it's clearly a bug waiting to bite
somebody.

Fix by pstrdup'ing the string to be saved for the error callback,
and then pfree'ing it next time through.  It's been like this for
a long time, so back-patch to all supported branches.

Discussion: https://postgr.es/m/48A4FA71-524E-41B9-953A-FD04EF36E2E7@yesql.se

Due to flaws in commit 3347c982, using WaitLatch() without
WL_LATCH_SET could cause an assertion failure or crash.  Repair.

While here, also add a check that the latch we're switching to belongs
to this backend, when changing from one latch to another.

Discussion: https://postgr.es/m/CA%2BhUKGK1607VmtrDUHQXrsooU%3Dap4g4R2yaoByWOOA3m8xevUQ%40mail.gmail.com

pg_restore previously coped with overlength TOC-file lines using some
complicated logic to ignore additional bufferloads.  While this isn't
wrong, since we don't expect that the interesting part of a line would
run to more than a dozen or so bytes, it's more complex than it needs
to be.  Use a StringInfo instead of a fixed-size buffer so that we can
process long lines as single entities and thus not need the extra
logic.

Daniel Gustafsson

Discussion: https://postgr.es/m/48A4FA71-524E-41B9-953A-FD04EF36E2E7@yesql.se

Use a StringInfo instead of a fixed-size buffer in parseServiceInfo().
While we've not heard complaints about the existing 255-byte limit,
it certainly seems possible that complex cases could run afoul of it.

Daniel Gustafsson

Discussion: https://postgr.es/m/48A4FA71-524E-41B9-953A-FD04EF36E2E7@yesql.se

Further experience says that the appending behavior offered by
pg_get_line_append is useful to only a very small minority of callers.
For most, the requirement to reset the buffer after each line is just
an error-prone nuisance.  Hence, invent another alternative call
pg_get_line_buf, which takes care of that detail.

Noted while reviewing a patch from Daniel Gustafsson.

Discussion: https://postgr.es/m/48A4FA71-524E-41B9-953A-FD04EF36E2E7@yesql.se

pgindent messes up entries in this file if their names match
typedef names.  While there's reason to avoid choosing conflicting
names, we have some historical exceptions, and there's no guarantee
that more duplicates won't appear in future.  Since this is a derived
file anyway, there's little harm in just excluding it.

I said yesterday that all our derived files are pgindent-clean, or else
explicitly excluded from indentation, but I'd forgotten about this one.
Now that project is really done, as confirmed by a test run.

Discussion: https://postgr.es/m/79ed5348-be7a-b647-dd40-742207186a22@2ndquadrant.com

The existing message about "a column definition list is only allowed for
functions returning "record"" could be given in some cases where it was
fairly confusing; in particular, a function with multiple OUT parameters
*does* return record according to pg_proc.  Break it down into a couple
more cases to deliver a more on-point complaint.  Per complaint from
Bruce Momjian.

Discussion: https://postgr.es/m/798909.1600562993@sss.pgh.pa.us

This completes the project of making all our derived files be
pgindent-clean (or else explicitly excluded from indentation),
so that no surprises result when running pgindent in a built-out
development tree.

Discussion: https://postgr.es/m/79ed5348-be7a-b647-dd40-742207186a22@2ndquadrant.com

99% of this is docs, but also a couple of comments.  No code changes.

Justin Pryzby

Discussion: https://postgr.es/m/20200919175804.GE30557@telsasoft.com

The standard order in PostgreSQL and other code is use strict first,
but some code was uselessly inconsistent about this.

Since we're bypassing the buffer manager, we need to call
PageSetChecksumInplace() directly. As reported by Justin Pryzby.

In the passing, add RelationOpenSmgr() calls before all smgrwrite() and
smgrextend() calls. Tom added one before the first smgrextend() call in
commit c2bb2870, which seems to be enough, but let's play it safe and
do it before each one. That's how it's done in the similar code in
nbtsort.c, too.

Discussion: https://www.postgresql.org/message-id/20200920224446.GF30557@telsasoft.com

Can't say if this fixes *all* cases, but at least we get through
the "point" regression test now, which hyrax's last run did not.

Report: https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=hyrax&dt=2020-09-19%2021%3A27%3A23

It's no longer necessary to assign explicit precedences to GENERATED,
NULL_P, PRESERVE, or STRIP_P.

Actually, we don't need to assign precedence to IDENT either; that was
really just there to govern the behavior of target_el's "a_expr IDENT"
production, which no longer ends with that terminal.  However, it seems
like a good idea to continue to do so, because it provides a reference
point for a precedence level that we can assign to other unreserved
keywords that lack a natural precedence level.

Research by Peter Eisentraut and John Naylor; comment rewrite by me.

Discussion: https://postgr.es/m/38ca86db-42ab-9b48-2902-337a0d6b8311@2ndquadrant.com

Remove various unused parameters in pg_dump code.  These have all
become unused over time or were never used.

Discussion: https://www.postgresql.org/message-id/flat/511bb100-f829-ba21-2f10-9f952ec06ead%402ndquadrant.com

Commit be0a6666 left behind a comment about the order of some tests that
didn't make sense without the expensive division, and in fact we might
as well change the order to one that fails more cheaply most of the time
as a micro-optimization.  Also, remove the "+ 1" applied to max_bucket,
to drop an instruction and match the original behavior.  Per review
from Tom Lane.

Discussion: https://postgr.es/m/VI1PR0701MB696044FC35013A96FECC7AC8F62D0%40VI1PR0701MB6960.eurprd07.prod.outlook.com

Since ancient times we have had support for a fill factor (maximum load
factor) to be set for a dynahash hash table, but:

1.  It was an integer, whereas for in-memory hash tables interesting
load factor targets are probably somewhere near the 0.75-1.0 range.

2.  It was implemented in a way that performed an expensive division
operation that regularly showed up in profiles.

3.  We are not aware of anyone ever having used a non-default value.

Therefore, remove support, effectively fixing it at 1.

Author: Jakub Wartak <Jakub.Wartak@tomtom.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/VI1PR0701MB696044FC35013A96FECC7AC8F62D0%40VI1PR0701MB6960.eurprd07.prod.outlook.com

Up to now, if you tried to omit "AS" before a column label in a SELECT
list, it would only work if the column label was an IDENT, that is not
any known keyword.  This is rather unfriendly considering that we have
so many keywords and are constantly growing more.  In the wake of commit
1ed6b895 it's possible to improve matters quite a bit.

We'd originally tried to make this work by having some of the existing
keyword categories be allowed without AS, but that didn't work too well,
because each category contains a few special cases that don't work
without AS.  Instead, invent an entirely orthogonal keyword property
"can be bare column label", and mark all keywords that way for which
we don't get shift/reduce errors by doing so.

It turns out that of our 450 current keywords, all but 39 can be made
bare column labels, improving the situation by over 90%.  This number
might move around a little depending on future grammar work, but it's
a pretty nice improvement.

Mark Dilger, based on work by myself and Robert Haas;
review by John Naylor

Discussion: https://postgr.es/m/38ca86db-42ab-9b48-2902-337a0d6b8311@2ndquadrant.com

According to buildfarm member sungazer, the behavior of VACUUM can be
unstable in these tests even if we prevent autovacuum from running on
the tables in question, apparently because even a manual vacuum can
behave differently depending on whether anything else is running that
holds back the global xmin. So use a temporary table instead, which
as of commit a7212be8 enables
vacuuming using a more aggressive cutoff.

This approach can't be used for the regression test that involves a
materialized view, but that test doesn't run vacuum, so it shouldn't
be prone to this particular failure mode.

Analysis by Tom Lane. Patch by Ashutosh Sharma and me.

Discussion: http://postgr.es/m/665524.1599948007@sss.pgh.pa.us

Author: Amit Langote
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/CA+HiwqE20oZoix13JyCeALpTf_SmjarZWtBFe5sND6zz+iupAw@mail.gmail.com

After commits 85f6b49c and 3ba59ccc, we can allow parallel inserts
which was earlier not possible as parallel group members won't conflict
for relation extension and page lock.  In those commits, we forgot to
update comments at few places.

Author: Amit Kapila
Reviewed-by: Robert Haas and Dilip Kumar
Backpatch-through: 13
Discussion: https://postgr.es/m/CAFiTN-tMrQh5FFMPx5aWJ+1gi1H6JxktEhq5mDwCHgnEO5oBkA@mail.gmail.com

It's not quite clear why commit 45b98057 has resulted in
some instability here, though interference from concurrent
autovacuum runs seems like a reasonable guess.  What is
clear is that the output ordering of the test queries is
underdetermined for no very good reason.  Extend the
ORDER BY keys in hopes of fixing the buildfarm.

Discussion: https://postgr.es/m/147499.1600351924@sss.pgh.pa.us

This feature has been a thorn in our sides for a long time, causing
many grammatical ambiguity problems.  It doesn't seem worth the
pain to continue to support it, so remove it.

There are some follow-on improvements we can make in the grammar,
but this commit only removes the bare minimum number of productions,
plus assorted backend support code.

Note that pg_dump and psql continue to have full support, since
they may be used against older servers.  However, pg_dump warns
about postfix operators.  There is also a check in pg_upgrade.

Documentation-wise, I (tgl) largely removed the "left unary"
terminology in favor of saying "prefix operator", which is
a more standard and IMO less confusing term.

I included a catversion bump, although no initial catalog data
changes here, to mark the boundary at which oprkind = 'r'
stopped being valid in pg_operator.

Mark Dilger, based on work by myself and Robert Haas;
review by John Naylor

Discussion: https://postgr.es/m/38ca86db-42ab-9b48-2902-337a0d6b8311@2ndquadrant.com

The "!" operator is our only built-in postfix operator.  Remove it,
on the way to removal of grammar support for postfix operators.

There is also a "!!" prefix operator, but since it's been marked
deprecated for most of its existence, we might as well remove it too.

Also zap the SQL alias function numeric_fac(), which seems to have
equally little reason to live.

Mark Dilger, based on work by myself and Robert Haas;
review by John Naylor

Discussion: https://postgr.es/m/38ca86db-42ab-9b48-2902-337a0d6b8311@2ndquadrant.com

I despair of people keeping the README file's notes in sync with
the actual exclusion list, so move the notes into the exclusion file.
Adjust the pgindent script to explicitly ignore comments in the file,
just in case (though it's hard to believe any would match filenames).

Extend the list so that it doesn't process any files we'd not wish it to
even in a fully-built-out development directory.  (There are still a
couple of derived files that it wants to reformat, but fixing the
generator scripts for those seems like fit material for a separate patch.)

Discussion: https://postgr.es/m/79ed5348-be7a-b647-dd40-742207186a22@2ndquadrant.com

Instead of hard-wiring specific verbosity levels into the option
processing of client applications, invent pg_logging_increase_verbosity()
and encourage clients to implement --verbose by calling that.  Then,
the common convention that more -v's gets you more verbosity just works.

In particular, this allows resurrection of the debug-grade messages that
have long existed in pg_dump and its siblings.  They were unreachable
before this commit due to lack of a way to select PG_LOG_DEBUG logging
level.  (It appears that they may have been unreachable for some time
before common/logging.c was introduced, too, so I'm not specifically
blaming cc8d4151 for the oversight.  One reason for thinking that is
that it's now apparent that _allocAH()'s message needs a null-pointer
guard.  Testing might have failed to reveal that before 96bf88d5.)

Discussion: https://postgr.es/m/1173106.1600116625@sss.pgh.pa.us

For parallel btree scan to work for array of scan keys, it should reach
BTPARALLEL_DONE state once for every distinct combination of array keys.
This is required to ensure that the parallel workers don't try to seize
blocks at the same time for different scan keys. We missed to update this
state when we discovered that the scan keys can't be satisfied.

Author: James Hunter
Reviewed-by: Amit Kapila
Tested-by: Justin Pryzby
Backpatch-through: 10, where it was introduced
Discussion: https://postgr.es/m/4248CABC-25E3-4809-B4D0-128E1BAABC3C@amazon.com

In the particular case of GRANTED BY, this is specified in the SQL
standard.  Since in PostgreSQL, CURRENT_ROLE is equivalent to
CURRENT_USER, and CURRENT_USER is already supported here, adding
CURRENT_ROLE is trivial.  The other cases are PostgreSQL extensions,
but for the same reason it also makes sense there.
Reviewed-by: Vik Fearing <vik@postgresfriends.org>
Reviewed-by: Asif Rehman <asifr.rehman@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/f2feac44-b4c5-f38f-3699-2851d6a76dc9%402ndquadrant.com

This adds a new optional support function to the GiST access method:
sortsupport. If it is defined, the GiST index is built by sorting all data
to the order defined by the sortsupport's comparator function, and packing
the tuples in that order to GiST pages. This is similar to how B-tree
index build works, and is much faster than inserting the tuples one by
one. The resulting index is smaller too, because the pages are packed more
tightly, upto 'fillfactor'. The normal build method works by splitting
pages, which tends to lead to more wasted space.

The quality of the resulting index depends on how good the opclass-defined
sort order is. A good order preserves locality of the input data.

As the first user of this facility, add 'sortsupport' function to the
point_ops opclass. It sorts the points in Z-order (aka Morton Code), by
interleaving the bits of the X and Y coordinates.

Author: Andrey Borodin
Reviewed-by: Pavel Borisov, Thomas Munro
Discussion: https://www.postgresql.org/message-id/1A36620E-CAD8-4267-9067-FB31385E7C0D%40yandex-team.ru

OpenSSL was quoted in inconsistent ways in many places of the docs,
sometimes with <application>, <productname> or just nothing.

Author: Daniel Gustafsson
Discussion: https://postgr.es/m/DA91E5F0-5F9D-41A7-A7A6-B91CDE0F1D63@yesql.se

It is not possible to get a list of foreign schemas as the server is not
known, so this provides instead a list of local schemas, which is more
useful than nothing if using a loopback server or having schema names
matching in the local and remote servers.

Author: Jeff Janes
Reviewed-by: Tom Lane, Michael Paquier
Discussion: https://postgr.es/m/CAMkU=1wr7Roj41q-XiJs=Uyc2xCmHhcGGy7J-peJQK-e+w=ghw@mail.gmail.com

Because the code path taken for SQL commands executed in a walsender
will update the process title, we pretty much have to update the
title for replication commands as well.  Otherwise, the title shows
"idle" for the rest of a logical walsender's lifetime once it's
executed any SQL command.

Playing with this, I confirm that a walsender now typically spends
most of its life reporting
	walsender postgres [local] START_REPLICATION
Considering this in isolation, it might be better to have it say
	walsender postgres [local] sending replication data
However, consistency with the other cases seems to be a stronger
argument.

In passing, remove duplicative pgstat_report_activity call.

Discussion: https://postgr.es/m/880181.1600026471@sss.pgh.pa.us

Adjust the whitespace in the emitted files so that it matches
what pgindent would do.  This makes the generated files look
like they match project style, and avoids confusion if someone
does run pgindent on the generated files.

Also, add probes.h to pgindent's exclusion list, because it can
confuse pgindent, plus there's not much point in processing it.

Daniel Gustafsson, additional fixes by me

Discussion: https://postgr.es/m/79ed5348-be7a-b647-dd40-742207186a22@2ndquadrant.com

Since commit fd5942c1 (2012, 9.3-era), walsender has been sending
completion tags for certain replication commands twice -- and they're
not even consistent.  Apparently neither libpq nor JDBC have a problem
with it, but it's not kosher.  Fix by remove the EndCommand() call in
the common code path for them all, and inserting specific calls to
EndReplicationCommand() specifically in those places where it's needed.

EndReplicationCommand() is a new simple function to send the completion
tag for replication commands.  Do this instead of sending a generic
SELECT completion tag for them all, which was also pretty bogus (if
innocuous).  While at it, change StartReplication() to use
EndReplicationCommand() instead of pg_puttextmessage().

In commit 2f966131, I failed to realize that replication commands
are not close-enough kin of regular SQL commands, so the
DROP_REPLICATION_SLOT tag I added is undeserved and a type pun.  Take it
out.

Backpatch to 13, where the latter commit appeared.  The duplicate tag
has been sent since 9.3, but since nothing is broken, it doesn't seem
worth fixing.

Per complaints from Tom Lane.

Discussion: https://postgr.es/m/1347966.1600195735@sss.pgh.pa.us