The back-patch of commit bbace569 had
the unfortunate effect of changing the layout of PGPROC in the
back-branches, which could break extensions. This happened because it
changed the delayChkpt from type bool to type int. So, change it back,
and add a new bool delayChkptEnd field instead. The new field should
fall within what used to be padding space within the struct, and so
hopefully won't cause any extensions to break.

Per report from Markus Wanner and discussion with Tom Lane and others.

Patch originally by me, somewhat revised by Markus Wanner per a
suggestion from Michael Paquier. A very similar patch was developed
by Kyotaro Horiguchi, but I failed to see the email in which that was
posted before writing one of my own.

Discussion: http://postgr.es/m/CA+Tgmoao-kUD9c5nG5sub3F7tbo39+cdr8jKaOVEs_1aBWcJ3Q@mail.gmail.com
Discussion: http://postgr.es/m/20220406.164521.17171257901083417.horikyota.ntt@gmail.com

Getting from get_raw_page() an all-zero page is considered as a valid
case by the buffer manager and it can happen for example when finding a
corrupted page with zero_damaged_pages enabled (using zero_damaged_pages
to look at corrupted pages happens), or after a crash when a relation
file is extended before any WAL for its new data is generated (before a
vacuum or autovacuum job comes in to do some cleanup).

However, all the functions of pageinspect, as of the index AMs (except
hash that has its own idea of new pages), heap, the FSM or the page
header have never worked with all-zero pages, causing various crashes
when going through the page internals.

This commit changes all the pageinspect functions to be compliant with
all-zero pages, where the choice is made to return NULL or no rows for
SRFs when finding a new page.  get_raw_page() still works the same way,
returning a batch of zeros in the bytea of the page retrieved.  A hard
error could be used but NULL, while more invasive, is useful when
scanning relation files in full to get a batch of results for a single
relation in one query.  Tests are added for all the code paths
impacted.

Reported-by: Daria Lepikhova
Author: Michael Paquier
Discussion: https://postgr.es/m/561e187b-3549-c8d5-03f5-525c14e65bd0@postgrespro.ru
Backpatch-through: 10

heap_fetch() used to have a "keep_buf" parameter that told it to return
ownership of the buffer pin to the caller after finding that the
requested tuple TID exists but is invisible to the specified snapshot.
This was thoughtlessly removed in commit 5db6df0c, which broke
heapam_tuple_lock() (formerly EvalPlanQualFetch) because that function
needs to do more accesses to the tuple even if it's invisible.  The net
effect is that we would continue to touch the page for a microsecond or
two after releasing pin on the buffer.  Usually no harm would result;
but if a different session decided to defragment the page concurrently,
we could see garbage data and mistakenly conclude that there's no newer
tuple version to chain up to.  (It's hard to say whether this has
happened in the field.  The bug was actually found thanks to a later
change that allowed valgrind to detect accesses to non-pinned buffers.)

The most reasonable way to fix this is to reintroduce keep_buf,
although I made it behave slightly differently: buffer ownership
is passed back only if there is a valid tuple at the requested TID.
In HEAD, we can just add the parameter back to heap_fetch().
To avoid an API break in the back branches, introduce an additional
function heap_fetch_extended() in those branches.

In HEAD there is an additional, less obvious API change: tuple->t_data
will be set to NULL in all cases where buffer ownership is not returned,
in particular when the tuple exists but fails the time qual (and
!keep_buf).  This is to defend against any other callers attempting to
access non-pinned buffers.  We concluded that making that change in back
branches would be more likely to introduce problems than cure any.

In passing, remove a comment about heap_fetch that was obsoleted by
9a8ee1dc.

Per bug #17462 from Daniil Anisimov.  Back-patch to v12 where the bug
was introduced.

Discussion: https://postgr.es/m/17462-9c98a0f00df9bd36@postgresql.org

It's more accurate to say that the query identifier is not shown when
compute_query_id = regress rather than to say it is hidden.

This change (ebf6c5249) appeared in v14, so it makes sense to backpatch
this small adjustment to keep the documents consistent between v14 and
master.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20220411020336.GB26620@telsasoft.com
Backpatch-through: 14, where compute_query_id = regress was added

This was made optional in 959f6d6a.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20220411020336.GB26620@telsasoft.com
Backpatch-through: 13, where -B was made optional

Google seems to like to return textsearch.html for queries about
GIN and GiST indexes, even though it's not a primary reference
for either.  It seems likely that that's because those keywords
appear in the page title.  Since "GIN and GiST Index Types" is
not a very apposite title for this material anyway, rename the
section in hopes of stopping that.

Also provide explicit links to the GIN and GiST chapters, to help
anyone who finds their way to this page regardless.

Per gripe from Jan Piotrowski.  Back-patch to supported branches.
(Unfortunately Google is likely to continue returning the 9.1
version of this page, but improving that situation is a matter
for the www team.)

Discussion: https://postgr.es/m/164978902252.1276550.9330175733459697101@wrigleys.postgresql.org

It's misleading to call the data directory the "synchronized data
directory" when discussing a crash scenario when using pg_rewind's
--no-sync option.  Here we just remove the word "synchronized" to avoid
any possible confusion.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20220411020336.GB26620@telsasoft.com
Backpatch-through: 12, where --no-sync was added

With asserts disabled, late-model clang notices that this variable
is incremented but never otherwise read.

Discussion: https://postgr.es/m/3171401.1649275153@sss.pgh.pa.us

It's possible for the query that "waits for restart" to complete a
successful iteration before the postmaster has noticed its SIGKILL'd
child and begun the restart cycle.  (This is a bit hard to believe
perhaps, but it's been seen at least twice in the buildfarm, mainly
on ancient platforms that likely have quirky schedulers.)

To provide a more secure interlock, wait for the other session
we're using to report that it's been forcibly shut down.

Patch by me, based on a suggestion from Andres Freund.
Back-patch to v14 where this test case came in.

Discussion: https://postgr.es/m/1801850.1649047827@sss.pgh.pa.us

The expected backend message after SIGQUIT changed in commit
7e784d1d, but we missed updating this test case.  Also, experience
shows that we might sometimes get "could not send data to server"
instead of either of the libpq messages the test is looking for.

Per report from Mark Dilger.  Back-patch to v14 where the
backend message changed.

Discussion: https://postgr.es/m/17BD82D7-49AC-40C9-8204-E7ADD30321A0@enterprisedb.com

Remove circular "25.1.5.1. Multixacts And Wraparound" link that
references the section that the link itself appears in.  An explanation
of MultiXactId age appears only a few sentences before the link, so
there's no question that the link is superfluous at best.

Oversight in commit d5409295.

Author: Peter Geoghegan <pg@bowt.ie>
Backpatch: 14-

accidentally left behind by 4cb658af

Do not add OpenSSL dependencies to libpq pkg-config file if OpenSSL is
not enabled.  Oversight in beff361b.

Author: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/20220331163759.32665-1-fontaine.fabrice%40gmail.com

postgres_fdw would push ORDER BY clauses to the remote side without
verifying that the sort operator is safe to ship.  Moreover, it failed
to print a suitable USING clause if the sort operator isn't default
for the sort expression's type.  The net result of this is that the
remote sort might not have anywhere near the semantics we expect,
which'd be disastrous for locally-performed merge joins in particular.

We addressed similar issues in the context of ORDER BY within an
aggregate function call in commit 7012b132, but failed to notice
that query-level ORDER BY was broken.  Thus, much of the necessary
logic already existed, but it requires refactoring to be usable
in both cases.

Back-patch to all supported branches.  In HEAD only, remove the
core code's copy of find_em_expr_for_rel, which is no longer used
and really should never have been pushed into equivclass.c in the
first place.

Ronan Dunklau, per report from David Rowley;
reviews by David Rowley, Ranier Vilela, and myself

Discussion: https://postgr.es/m/CAApHDvr4OeC2DBVY--zVP83-K=bYrTD7F8SZDhN4g+pj2f2S-A@mail.gmail.com

Oversight in commit a59c79564.  Back-patch, as that was.
Noted by Peter Eisentraut.

Discussion: https://postgr.es/m/7f85ef6d-250b-f5ec-9867-89f0b16d019f@enterprisedb.com

Commit 61fa6ca79b3 accidentally wrote constrast instead of contrast.

Backpatch-through: 10
Discussion: https://postgr.es/m/88903179-5ce2-3d4d-af43-7830372bdcb6@enterprisedb.com

This reverts commit 49d9cfc68bf4.  The approach taken by this patch has
problems, so we'll come up with a radically different fix.

Discussion: https://postgr.es/m/CA+TgmoYcUPL+WOJL2ZzhH=zmrhj0iOQ=iCFM0SuYqBbqZEamEg@mail.gmail.com

When dealing with partitioned tables, counters for partitioned tables
are not updated when modifying child tables. This means autoanalyze may
not update optimizer statistics for the parent relations, which can
result in poor plans for some queries.

It's worth documenting this limitation, so that people are aware of it
and can take steps to mitigate it (e.g. by setting up a script executing
ANALYZE regularly).

Backpatch to v10. Older branches are affected too, of couse, but we no
longer maintain those.

Author: Justin Pryzby
Reviewed-by: Zhihong Yu, Tomas Vondra
Backpatch-through: 10
Discussion: https://postgr.es/m/20210913035409.GA10647%40telsasoft.com

pg_stat_get_replication_slot() accidentally was marked as non-strict, crashing
when called with NULL input. As it's already released, introduce an explicit
NULL check in 14, fix the catalog in HEAD.

Bumps catversion in HEAD.

Discussion: https://postgr.es/m/20220326212432.s5n2maw6kugnpyxw@alap3.anarazel.de
Backpatch: 14-, where replication slot stats were introduced

After closedir() dirent->d_name is not valid anymore. As there alerady are a
few places relying on the limited lifetime of pg_waldump, do so here as well,
and just pg_strdup() the string.

The bug was introduced in fc49e24f.

Found by UBSan, run locally.

Backpatch: 11-, like fc49e24f itself.

Commit 8c6d30f2 caused this function to fail to set *displen
in the PS_USE_NONE code path.  If the variable's previous value
had been negative, that'd lead to a memory clobber at some call
sites.  We'd managed not to notice due to very thin test coverage
of such configurations, but this appears to explain buildfarm member
lorikeet's recent struggles.

Credit to Andrew Dunstan for spotting the problem.  Back-patch
to v13 where the bug was introduced.

Discussion: https://postgr.es/m/136102.1648320427@sss.pgh.pa.us

A couple of code paths use the special area on the page passed by the
function caller, expecting to find some data in it.  However, feeding
an incorrect page can lead to out-of-bound reads when trying to access
the page special area (like a heap page that has no special area,
leading PageGetSpecialPointer() to grab a pointer outside the allocated
page).

The functions used for hash and btree indexes have some protection
already against that, while some other functions using a relation OID
as argument would make sure that the access method involved is correct,
but functions taking in input a raw page without knowing the relation
the page is attached to would run into problems.

This commit improves the set of checks used in the code paths of BRIN,
btree (including one check if a leaf page is found with a non-zero
level), GIN and GiST to verify that the page given in input has a
special area size that fits with each access method, which is done
though PageGetSpecialSize(), becore calling PageGetSpecialPointer().

The scope of the checks done is limited to work with pages that one
would pass after getting a block with get_raw_page(), as it is possible
to craft byteas that could bypass existing code paths.  Having too many
checks would also impact the usability of pageinspect, as the existing
code is very useful to look at the content details in a corrupted page,
so the focus is really to avoid out-of-bound reads as this is never a
good thing even with functions whose execution is limited to
superusers.

The safest approach could be to rework the functions so as these fetch a
block using a relation OID and a block number, but there are also cases
where using a raw page is useful.

Tests are added to cover all the code paths that needed such checks, and
an error message for hash indexes is reworded to fit better with what
this commit adds.

Reported-By: Alexander Lakhin
Author: Julien Rouhaud, Michael Paquier
Discussion: https://postgr.es/m/16527-ef7606186f0610a1@postgresql.org
Discussion: https://postgr.es/m/561e187b-3549-c8d5-03f5-525c14e65bd0@postgrespro.ru
Backpatch-through: 10

clang 13 with -Wextra warns that "performing pointer subtraction with
a null pointer has undefined behavior" in the places where freepage.c
tries to set a relptr variable to constant NULL.  This appears to be
a compiler bug, but it's unlikely to get fixed instantly.  Fortunately,
we can work around it by introducing an inline support function, which
seems like a good change anyway because it removes the macro's existing
double-evaluation hazard.

Backpatch to v10 where this code was introduced.

Patch by me, based on an idea of Andres Freund's.

Discussion: https://postgr.es/m/48826.1648310694@sss.pgh.pa.us

The previous method for doing that was to write zeroes into a
predetermined set of page locations.  However, there's a roughly
1-in-64K chance that the existing checksum will match by chance,
and yesterday several buildfarm animals started to reproducibly
see that, resulting in test failures because no checksum mismatch
was reported.

Since the checksum includes the page LSN, test success depends on
the length of the installation's WAL history, which is affected by
(at least) the initial catalog contents, the set of locales installed
on the system, and the length of the pathname of the test directory.
Sooner or later we were going to hit a chance match, and today is
that day.

Harden these tests by specifically inverting the checksum field and
leaving all else alone, thereby guaranteeing that the checksum is
incorrect.

In passing, fix places that were using seek() to set up for syswrite(),
a combination that the Perl docs very explicitly warn against.  We've
probably escaped problems because no regular buffered I/O is done on
these filehandles; but if it ever breaks, we wouldn't deserve or get
much sympathy.

Although we've only seen problems in HEAD, now that we recognize the
environmental dependencies it seems like it might be just a matter
of time until someone manages to hit this in back-branch testing.
Hence, back-patch to v11 where we started doing this kind of test.

Discussion: https://postgr.es/m/3192026.1648185780@sss.pgh.pa.us

Crash recovery on standby may encounter missing directories when
replaying create database WAL records.  Prior to this patch, the standby
would fail to recover in such a case.  However, the directories could be
legitimately missing.  Consider a sequence of WAL records as follows:

    CREATE DATABASE
    DROP DATABASE
    DROP TABLESPACE

If, after replaying the last WAL record and removing the tablespace
directory, the standby crashes and has to replay the create database
record again, the crash recovery must be able to move on.

This patch adds a mechanism similar to invalid-page tracking, to keep a
tally of missing directories during crash recovery.  If all the missing
directory references are matched with corresponding drop records at the
end of crash recovery, the standby can safely continue following the
primary.

Backpatch to 13, at least for now.  The bug is older, but fixing it in
older branches requires more careful study of the interactions with
commit e6d80695, which appeared in 13.

A new TAP test file is added to verify the condition.  However, because
it depends on commit d6d317dbf615, it can only be added to branch
master.  I (Álvaro) manually verified that the code behaves as expected
in branch 14.  It's a bit nervous-making to leave the code uncovered by
tests in older branches, but leaving the bug unfixed is even worse.
Also, the main reason this fix took so long is precisely that we
couldn't agree on a good strategy to approach testing for the bug, so
perhaps this is the best we can do.
Diagnosed-by: Paul Guo <paulguo@gmail.com>
Author: Paul Guo <paulguo@gmail.com>
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Author: Asim R Praveen <apraveen@pivotal.io>
Discussion: https://postgr.es/m/CAEET0ZGx9AvioViLf7nbR_8tH9-=27DN5xWJ2P9-ROH16e4JUA@mail.gmail.com

If TRUNCATE causes some buffers to be invalidated and thus the
checkpoint does not flush them, TRUNCATE must also ensure that the
corresponding files are truncated on disk. Otherwise, a replay
from the checkpoint might find that the buffers exist but have
the wrong contents, which may cause replay to fail.

Report by Teja Mupparti. Patch by Kyotaro Horiguchi, per a design
suggestion from Heikki Linnakangas, with some changes to the
comments by me. Review of this and a prior patch that approached
the issue differently by Heikki Linnakangas, Andres Freund, Álvaro
Herrera, Masahiko Sawada, and Tom Lane.

Discussion: http://postgr.es/m/BYAPR06MB6373BF50B469CA393C614257ABF00@BYAPR06MB6373.namprd06.prod.outlook.com

Noticed via -fsanitize=undefined. Introduced when a few columns in
GetConfigOptionByNum() / pg_settings started to be translated in 72be8c29 /
PG 12.

Backpatch to all affected branches, for the same reasons as 46ab07ffda9.

Discussion: https://postgr.es/m/20220323173537.ll7klrglnp4gn2um@alap3.anarazel.de
Backpatch: 12-

Noticed via -fsanitize=undefined.

Backpatch to all branches, for the same reasons as 46ab07ffda9.

Discussion: https://postgr.es/m/20220323173537.ll7klrglnp4gn2um@alap3.anarazel.de
Backpatch: 10-

When building with sanitizers the sanitizer library provides dlopen, but not
dlsym(), making configure think that -ldl isn't needed. Just checking for
dlsym() ought to suffice, hard to see dlsym() being provided without dlopen()
also being provided.

Backpatch to all branches, for the same reasons as 46ab07ffda9.
Reviewed-By: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/20220323173537.ll7klrglnp4gn2um@alap3.anarazel.de
Backpatch: 10-

It seems possible for the condition being tested to be true in
production, and nobody would never know (except when some data
eventually becomes corrupt?).

Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m//202109040001.zky3wgv2qeqg@alvherre.pgsql

Invalidate abortedRecPtr and missingContrecPtr after a missing
continuation record is successfully skipped on a standby. This fixes a
PANIC caused when a recently promoted standby attempts to write an
OVERWRITE_RECORD with an LSN of the previously read aborted record.

Backpatch to 10 (all stable versions).

Author: Sami Imseih <simseih@amazon.com>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/44D259DE-7542-49C4-8A52-2AB01534DCA9@amazon.com

As commits b700f96c and 3414099c did for the reloptions test, make
sure VACUUM can always truncate the table as expected.

Back-patch to 12, where vacuum_truncate arrived.

Discussion: https://postgr.es/m/CAD21AoCNoWjYkdEtr%2BVDoF9v__V905AedKZ9iF%3DArgCtrbxZqw%40mail.gmail.com

When cross-building to windows, or building with mingw on windows, the build
could fail with
  x86_64-w64-mingw32-gcc: error: win32ver.o: No such file or director
because pg_dumpall didn't depend on WIN32RES, but it's recipe references
it. The build nevertheless succeeded most of the time, due to
pg_dump/pg_restore having the required dependency, causing win32ver.o to be
built.
Reported-By: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/CA+hUKGJeekpUPWW6yCVdf9=oBAcCp86RrBivo4Y4cwazAzGPng@mail.gmail.com
Backpatch: 10-, omission present on all live branches

This issue is environment-sensitive, where the SSL tests could fail in
various way by feeding on defaults provided by sslcert, sslkey,
sslrootkey, sslrootcert, sslcrl and sslcrldir coming from a local setup,
as of ~/.postgresql/ by default.  Horiguchi-san has reported two
failures, but more advanced testing from me (aka inclusion of garbage
SSL configuration in ~/.postgresql/ for all the configuration
parameters) has showed dozens of failures that can be triggered in the
whole test suite.

History has showed that we are not good when it comes to address such
issues, fixing them locally like in dd877998, and such problems keep
appearing.  This commit strengthens the entire test suite to put an end
to this set of problems by embedding invalid default values in all the
connection strings used in the tests.  The invalid values are prefixed
in each connection string, relying on the follow-up values passed in the
connection string to enforce any invalid value previously set.  Note
that two tests related to CRLs are required to fail with certain pre-set
configurations, but we can rely on enforcing an empty value instead
after the invalid set of values.

Reported-by: Kyotaro Horiguchi
Reviewed-by: Andrew Dunstan, Daniel Gustafsson, Kyotaro Horiguchi
Discussion: https://postgr.es/m/20220316.163658.1122740600489097632.horikyota.ntt@gmail.com
backpatch-through: 10

The planner needs to treat GroupingFunc like Aggref for many purposes,
in particular with respect to processing of the argument expressions,
which are not to be evaluated at runtime.  A few places hadn't gotten
that memo, notably including subselect.c's processing of outer-level
aggregates.  This resulted in assertion failures or wrong plans for
cases in which a GROUPING() construct references an outer aggregation
level.

Also fix missing special cases for GroupingFunc in cost_qual_eval
(resulting in wrong cost estimates for GROUPING(), although it's
not clear that that would affect plan shapes in practice) and in
ruleutils.c (resulting in excess parentheses in pretty-print mode).

Per bug #17088 from Yaoguang Chen.  Back-patch to all supported
branches.

Richard Guo, Tom Lane

Discussion: https://postgr.es/m/17088-e33882b387de7f5c@postgresql.org

DROP INDEX needs to lock the index's table before the index itself,
else it will deadlock against ordinary queries that acquire the
relation locks in that order.  This is correctly mechanized for
plain indexes by RangeVarCallbackForDropRelation; but in the case of
a partitioned index, we neglected to lock the child tables in advance
of locking the child indexes.  We can fix that by traversing the
inheritance tree and acquiring the needed locks in RemoveRelations,
after we have acquired our locks on the parent partitioned table and
index.

While at it, do some refactoring to eliminate confusion between
the actual and expected relkind in RangeVarCallbackForDropRelation.
We can save a couple of syscache lookups too, by having that function
pass back info that RemoveRelations will need.

Back-patch to v11 where partitioned indexes were added.

Jimmy Yih, Gaurab Dey, Tom Lane

Discussion: https://postgr.es/m/BYAPR05MB645402330042E17D91A70C12BD5F9@BYAPR05MB6454.namprd05.prod.outlook.com

The example used "TimeoutSec=0", but systemd's documented way to get
the desired effect is "TimeoutSec=infinity".

Discussion: https://postgr.es/m/164770078557.670.5467111518383664377@wrigleys.postgresql.org

This command flavor is supported, but there was nothing in the
documentation about it.

Author: Yugo Nagata
Discussion: https://postgr.es/m/20220316133337.5dc9740abfa24c25ec9f67f5@sraoss.co.jp
Backpatch-through: 10

The output of table_to_xmlschema() and allied functions includes
a regex describing valid values for these types ... but the regex
was itself invalid, as it failed to escape a literal "+" sign.

Report and fix by Renan Soares Lopes.  Back-patch to all
supported branches.

Discussion: https://postgr.es/m/7f6fabaa-3f8f-49ab-89ca-59fbfe633105@me.com