Since pg_depend can contain duplicate entries, we need to eliminate
those in information schema views that build on pg_depend, using
DISTINCT.  Some of the older views already did that correctly, but
some of the more recently added ones didn't.  (In some of these views,
it might not be possible to reproduce the issue because of how the
implementation happens to deduplicate dependencies while recording
them, but it seems better to keep this consistent in all cases.)

Should be %u rather than %d.

Use %lld and cast to long long int instead.

Not enabling compute_query_id would disable pg_stat_statements even if
the module is listed in shared_preload_libraries, so add it to the
minimum configuration set as listed in its documentation.

Author: Greg Nancarrow
Reviewed-by: Julien Rouhaud, Bharath Rupireddy
Discussion: https://postgr.es/m/CAJcOf-fXyb2QiDbwftD813UF70w-+BsK-03bFp1GrijXU9GQYQ@mail.gmail.com

This compatibility has been added in 45b98057, but psql forgot the call.

Author: Wei Wang
Reviewed-by: Aleksander Alekseev
Discussion: https://postgr.es/m/OS3PR01MB6275935F62E161BCD393D6559E489@OS3PR01MB6275.jpnprd01.prod.outlook.com

While tracking down the bug fixed in the preceding commit, I got quite
annoyed by the low quality of spg_desc's output.  Add missing fields,
try to make the formatting consistent.

Commit f003d9f8 left this macro with inadequate (or, one could say,
too much) parenthesization.  Which was catastrophic to the correctness
of calls such as "if (!XLogRecHasBlockRef(record, 1)) ...".  There
are only a few of those, which perhaps explains why we didn't notice
immediately (with our general weakness of WAL replay testing being
another factor).  I found it by debugging intermittent replay failures
like

2021-04-08 14:33:30.191 EDT [29463] PANIC:  failed to locate backup block with ID 1
2021-04-08 14:33:30.191 EDT [29463] CONTEXT:  WAL redo at 0/95D3438 for SPGist/ADD_NODE: off 1; blkref #0: rel 1663/16384/25998, blk 1

log_statement is issued before query_id can be computed, so properly
clear the value, and document the interaction.

Reported-by: Fujii Masao, Michael Paquier

Discussion: https://postgr.es/m/YHPkU8hFi4no4NSw@paquier.xyz

Author: Julien Rouhaud

Previously, it was pg_stat_activity.queryid to match the
pg_stat_statements queryid column.  This is an adjustment to patch
4f0b0966.  This also adjusts some of the internal function calls to
match.  Catversion bumped.

Reported-by: Álvaro Herrera, Julien Rouhaud

Discussion: https://postgr.es/m/20210408032704.GA7498@alvherre.pgsql

I didn't particularly like this function name, as it fails to
express what's going on.  Also, returning the sort expression
alone isn't too helpful --- typically, a caller would also
need some other fields of the EquivalenceMember.  But the
sole caller really only needs a bool result, so let's make
it "bool relation_can_be_sorted_early()".

Discussion: https://postgr.es/m/91f3ec99-85a4-fa55-ea74-33f85a5c651f@swarm64.com

An oversight introduced by the incremental-sort patches caused
"could not find pathkey item to sort" errors in some situations
where a sort key involves an aggregate or window function.

The basic problem here is that find_em_expr_usable_for_sorting_rel
isn't properly modeling what prepare_sort_from_pathkeys will do
later.  Rather than hoping we can keep those functions in sync,
let's refactor so that they actually share the code for
identifying a suitable sort expression.

With this refactoring, tlist.c's tlist_member_ignore_relabel
is unused.  I removed it in HEAD but left it in place in v13,
in case any extensions are using it.

Per report from Luc Vlaming.  Back-patch to v13 where the
problem arose.

James Coleman and Tom Lane

Discussion: https://postgr.es/m/91f3ec99-85a4-fa55-ea74-33f85a5c651f@swarm64.com

Commit b34ca595 provided for installation-aware instances of
PostgresNode. However, it turns out that IPC::Run works against this by
caching the path to a binary and not consulting the path again, even if
it has changed. We work around this by calling Postgres binaries with
the installed path rather than just a bare name to be looked up in the
environment path, if there is an installed path. For the common case
where there is no installed path we continue to use the bare command
name.

Diagnosis and solution from Mark Dilger

Discussion: https://postgr.es/m/E8F512F8-B4D6-4514-BA8D-2E671439DA92@enterprisedb.com

Author: Julien Rouhaud
Backpatch-through: 11
Discussion: https://postgr.es/m/20210420121659.odjueyd4rpilorn5@nol

Document VACUUM's soft assumption that any LP_DEAD items encountered
during pruning will become LP_UNUSED items before VACUUM finishes up.
This is integral to the accounting used by VACUUM to generate its final
report on the table to the stats collector.  It also affects how VACUUM
determines which heap pages are truncatable.  In both cases VACUUM is
concerned with the likely contents of the page in the near future, not
the current contents of the page.

This state of affairs created the false impression that VACUUM's dead
tuple accounting had significant difference with similar accounting used
during ANALYZE.  There were and are no substantive differences, at least
when the soft assumption completely works out.  This is far clearer now.

Also document cases where things don't quite work out for VACUUM's dead
tuple accounting.  It's possible that a significant number of LP_DEAD
items will be left behind by VACUUM, and won't be recorded as remaining
dead tuples in VACUUM's statistics collector report.  This behavior
dates back to commit a96c41fe, which taught VACUUM to run without index
and heap vacuuming at the user's request.  The failsafe mechanism added
to VACUUM more recently by commit 1e55e7d1 takes the same approach to
dead tuple accounting.
Reported-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAH2-Wz=Jmtu18PrsYq3EvvZJGOmZqSO2u3bvKpx9xJa5uhNp=Q@mail.gmail.com

Should be signed, not unsigned.

In the new test after resetting the stats, we were not waiting for the
stats message to be delivered. Also, we need to decode the results for
the new test, otherwise, it will show the old stats.

In passing,
a. Change docs added by commit f5fc2f5b as per suggestion by
Justin Pryzby.
b. Bump the PGSTAT_FILE_FORMAT_ID as commit f5fc2f5b changes the file
format of stats.

Reported-by: Tom Lane based on buildfarm reports
Author: Vignesh C, Justin Pryzby
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de

Author: Justin Pryzby
Discussion: https://postgr.es/m/20210416070310.GG3315@telsasoft.com

A couple of tests have been using 0 as magic constant while SEEK_SET can
be used instead.  This makes the code easier to understand, and more
consistent with the changes done in 3c5b0685.

Per discussion with Andrew Dunstan.

Discussion: https://postgr.es/m/YHrc24AgJQ6tQ1q0@paquier.xyz

Add a few words of comment to explain why SIGURG doesn't follow the
dummy_handler pattern used for SIGUSR2, since that might otherwise
appear to be a bug.

Discussion: https://postgr.es/m/4006115.1618577212%40sss.pgh.pa.us

Should be %u rather than %d.

As it stands, find_expr_references_walker() pays attention to leaf-node
collation fields while ignoring the input collations of actual function
and operator nodes.  That seems exactly backwards from a semantic
standpoint, and it leads to reporting dependencies on collations that
really have nothing to do with the expression's behavior.

Hence, rewrite to look at function input collations instead.  This
isn't completely perfect either; it fails to account for the behavior
of record_eq and its siblings.  (The previous coding at least gave an
approximation of that, though I think it could be fooled pretty easily
into considering the columns of irrelevant composite types.)  We may
be able to improve on this later, but for now this should satisfy the
buildfarm members that didn't like ef387bed.

In passing fix some oversights in GetTypeCollations(), and get
rid of its duplicative de-duplications.  (I'm worried that it's
still potentially O(N^2) or worse, but this makes it a little
better.)

Discussion: https://postgr.es/m/3564817.1618420687@sss.pgh.pa.us

Ooops, forgot to s/system_views.sql/system_functions.sql/g
in this part of 767982e3.

No need for an additional catversion bump, I think, since
these strings are gone by the time initdb finishes.

Discussion: https://postgr.es/m/3956760.1618529139@sss.pgh.pa.us

Adopt the new pre-parsed representation for all built-in and
information_schema SQL-language functions, except for a small
number that can't presently be converted because they have
polymorphic arguments.

This eliminates residual hazards around search-path safety of
these functions, and might provide some small performance benefits
by reducing parsing costs.  It seems useful also to provide more
test coverage for the SQL-standard-body feature.

Discussion: https://postgr.es/m/3956760.1618529139@sss.pgh.pa.us

Invent system_functions.sql to carry the function definitions that
were formerly in system_views.sql.  The function definitions were
already a quarter of the file and are about to be more, so it seems
appropriate to give them their own home.

In passing, fix an oversight in dfb75e47: it neglected to call
check_input() for system_constraints.sql.

Discussion: https://postgr.es/m/3956760.1618529139@sss.pgh.pa.us

In order to avoid getting old logfile contents certain functions in
PostgresNode were doing one of two things. On Windows it rotated the
logfile and restarted the server, while elsewhere it truncated the log
file. Both of these are unnecessary. We borrow from the buildfarm which
does this instead: note the size of the logfile before we start, and
then when fetching the logfile skip to that position before accumulating
contents. This is spelled differently on Windows but the effect is the
same. This is largely centralized in TestLib's slurp_file function,
which has a new optional parameter, the offset to skip to before
starting to reading the file. Code in the client becomes much neater.

Backpatch to all live branches.

Michael Paquier, slightly modified by me.

Discussion: https://postgr.es/m/YHajnhcMAI3++pJL@paquier.xyz

recordMultipleDependencies had the wrong scope for its "version"
variable, allowing a version label to leak from the collation entry it
was meant for to subsequent non-collation entries.  This is relatively
hard to trigger because of the OID-descending order that the inputs
will normally arrive in: subsequent non-collation items will tend to
be pinned.  But it can be exhibited easily with a custom collation.

Also, don't special-case the default collation, but instead ignore
pinned-ness of a collation when we've found a version for it.  This
avoids creating useless pg_depend entries, and removes a not-very-
future-proof assumption that C, POSIX, and DEFAULT are the only
pinned collations.

A small problem is that, because the default collation may or may
not have a version, the regression tests can't assume anything about
whether dependency entries will be made for it.  This seems OK though
since it's now handled just the same as other collations, and we have
test cases for both versioned and unversioned collations.

Fixes oversights in commit 257836a7.  Thanks to Julien Rouhaud
for review.

Discussion: https://postgr.es/m/3564817.1618420687@sss.pgh.pa.us

This is only a latent bug, since these calls are only reached for
non-text output formats, and currently none of those will print
the units.  Still, we should get it right in case that ever changes.

Justin Pryzby

Discussion: https://postgr.es/m/20210415163846.GA3315@telsasoft.com

Only track BEGIN...END blocks if they are in a CREATE [OR REPLACE]
{FUNCTION|PROCEDURE} statement.  Ignore if in parentheses.
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Discussion: https://www.postgresql.org/message-id/cee01d26fe55bc086b3bcf10bfe4e8d450e2f608.camel@cybertec.at

Author: Erik Rijkers
Discussion: https://postgr.es/m/1219476687.20432.1617452918468@webmailclassic.xs4all.nl
Backpatch-through: 12

This adds the statistics about total transactions count and total
transaction data logically sent to the decoding output plugin from
ReorderBuffer. Users can query the pg_stat_replication_slots view to check
these stats.

Suggested-by: Andres Freund
Author: Vignesh C and Amit Kapila
Reviewed-by: Sawada Masahiko, Amit Kapila
Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de

Warn users that locales with traditional Windows NLS names like
"English_United States.1252" won't provide version information, and that
something like initdb --lc-collate=en-US would be needed to fix that
problem for the initial template databases.

Discussion: https://postgr.es/m/CA%2BhUKGJ_hk3rU%3D%3Dg2FpAMChb_4i%2BTJacpjjqFsinY-tRM3FBmA%40mail.gmail.com

Without this, we lose error cursor positions, as shown in the
modified regression test result.

Discussion: https://postgr.es/m/2197698.1617984583@sss.pgh.pa.us

This reverts commit b3ee4c50.
We don't need it in the wake of the preceding commit, which
added an upstream check that the querystring isn't null.

Discussion: https://postgr.es/m/2197698.1617984583@sss.pgh.pa.us

Commit e717a9a1 changed the longstanding rule that prosrc is NOT NULL
because when a SQL-language function is written in SQL-standard style,
we don't currently have anything useful to put there.  This seems a poor
decision though, as it could easily have negative impacts on external
PLs (opening them to crashes they didn't use to have, for instance).
SQL-function-related code can just as easily test "is prosqlbody not
null" as "is prosrc null", so there's no real gain there either.
Hence, revert the NOT NULL marking removal and adjust related logic.

For now, we just put an empty string into prosrc for SQL-standard
functions.  Maybe we'll have a better idea later, although the
history of things like pg_attrdef.adsrc suggests that it's not
easy to maintain a string equivalent of a node tree.

This also adds an assertion that queryDesc->sourceText != NULL
to standard_ExecutorStart.  We'd been silently relying on that
for awhile, so let's make it less silent.

Also fix some overlooked documentation and test cases.

Discussion: https://postgr.es/m/2197698.1617984583@sss.pgh.pa.us

These queries could show unexpected entries if the core system,
or concurrently-running test scripts, created any functions that
would appear in the information_schema views.  Restrict them
to showing functions belonging to this test's schema, as the
far-older nearby test case does.

Per experimentation with conversion of some built-in functions
to SQL-function-body style.