While prepare_sort_from_pathkeys has to be concerned about matching up
a volatile expression to the proper tlist entry, we don't need to do
that in find_em_expr_usable_for_sorting_rel becausee such a sort will
have to be postponed anyway.

Author: James Coleman
Reviewed-by: Tomas Vondra
Backpatch-through: 13
Discussion: https://postgr.es/m/CAAaqYe8cK3g5CfLC4w7bs%3DhC0mSksZC%3DH5M8LSchj5e5OxpTAg%40mail.gmail.com

While we do allow SRFs in ORDER BY, scan/join processing should not
consider such cases - such sorts should only happen via final Sort atop
a ProjectSet. So make sure we don't try adding such sorts below Gather
Merge, just like we do for expressions that are volatile and/or not
parallel safe.

Backpatch to PostgreSQL 13, where this code was introduced as part of
the Incremental Sort patch.

Author: James Coleman
Reviewed-by: Tomas Vondra
Backpatch-through: 13
Discussion: https://postgr.es/m/CAAaqYe8cK3g5CfLC4w7bs=hC0mSksZC=H5M8LSchj5e5OxpTAg@mail.gmail.com
Discussion: https://postgr.es/m/295524.1606246314%40sss.pgh.pa.us

The jsonb || jsonb operator arbitrarily rejected certain combinations
of scalar and non-scalar inputs, while being willing to concatenate
other combinations.  This was of course quite undocumented.  Rather
than trying to document it, let's just remove the restriction,
creating a uniform rule that unless we are handling an object-to-object
concatenation, non-array inputs are converted to one-element arrays,
resulting in an array-to-array concatenation.  (This does not change
the behavior for any case that didn't throw an error before.)

Per complaint from Joel Jacobson.  Back-patch to all supported branches.

Discussion: https://postgr.es/m/163099.1608312033@sss.pgh.pa.us

Commit ebb7ae83 ensured we ignore pathkeys with volatile expressions
when considering adding a sort below a Gather Merge. Turns out we need
to care about parallel safety of the pathkeys too, otherwise we might
try sorting e.g. on results of a correlated subquery (as demonstrated
by a report from Luis Roberto).

Initial investigation by Tom Lane, patch by James Coleman. Backpatch
to 13, where the code was instroduced (as part of Incremental Sort).

Reported-by: Luis Roberto
Author: James Coleman
Reviewed-by: Tomas Vondra
Backpatch-through: 13
Discussion: https://postgr.es/m/622580997.37108180.1604080457319.JavaMail.zimbra%40siscobra.com.br
Discussion: https://postgr.es/m/CAAaqYe8cK3g5CfLC4w7bs=hC0mSksZC=H5M8LSchj5e5OxpTAg@mail.gmail.com

generate_useful_gather_paths used to skip unsorted paths (without any
pathkeys), but that is unnecessary - the later code actually can handle
such paths just fine by adding a Sort node. This is clearly a thinko,
preventing construction of useful plans.

Backpatch to 13, where Incremental Sort was introduced.

Author: James Coleman
Reviewed-by: Tomas Vondra
Backpatch-through: 13
Discussion: https://postgr.es/m/CAAaqYe8cK3g5CfLC4w7bs=hC0mSksZC=H5M8LSchj5e5OxpTAg@mail.gmail.com

Discussion: https://postgr.es/m/X%2BBP8XE0UpIB6Yvh%40paquier.xyz
Author: Michael Paquier

The same logic was present for collation commands, SASLprep and
pgcrypto, so this removes some code.

Author: Michael Paquier
Reviewed-by: Stephen Frost, Heikki Linnakangas
Discussion: https://postgr.es/m/X9womIn6rne6Gud2@paquier.xyz

6df7a969 introduces multirange types, whose typanalyze function shares
infrastructure with range types typanalyze function.  Since 6df7a969,
information about type gathered by statistics is filled from typcache.
But typalign is mistakenly always set to double.  This commit fixes this
oversight.

The separate "cd" command before invoking psql made sense (or at least
I thought so) when it was added in commit ed193933.  But 4e3a6163
removed the supporting text that explained when to use it, making it
just confusing.  So drop it.

Also switch from four-dot to three-dot filler for the unsupplied
part of the path, since at least one person has read the four-dot
filler as a typo for "../..".  And fix these/those inconsistency.

Discussion: https://postgr.es/m/160837647714.673.5195186835607800484@wrigleys.postgresql.org

Point out the workaround to be used if you want to write a script
file name that includes "@".  Clean up the text a little.

Fabien Coelho, additional wordsmithing by me

Discussion: https://postgr.es/m/1c4e81550d214741827a03292222db8d@G08CNEXMBPEKD06.g08.fujitsu.local

Same type of issue as in commit 53d4f5fe and earlier fixes; also
found by apparently-more-picky-than-the-buildfarm valgrind testing.
This one is an oversight in commit 98681675.  Since that's new in
HEAD, no need for a back-patch.

This commit fixes two wrong version number checks and one wrong check for null.

Multiranges are basically sorted arrays of non-overlapping ranges with
set-theoretic operations defined over them.

Since v14, each range type automatically gets a corresponding multirange
datatype.  There are both manual and automatic mechanisms for naming multirange
types.  Once can specify multirange type name using multirange_type_name
attribute in CREATE TYPE.  Otherwise, a multirange type name is generated
automatically.  If the range type name contains "range" then we change that to
"multirange".  Otherwise, we add "_multirange" to the end.

Implementation of multiranges comes with a space-efficient internal
representation format, which evades extra paddings and duplicated storage of
oids.  Altogether this format allows fetching a particular range by its index
in O(n).

Statistic gathering and selectivity estimation are implemented for multiranges.
For this purpose, stored multirange is approximated as union range without gaps.
This field will likely need improvements in the future.

Catversion is bumped.

Discussion: https://postgr.es/m/CALNJ-vSUpQ_Y%3DjXvTxt1VYFztaBSsWVXeF1y6gTYQ4bOiWDLgQ%40mail.gmail.com
Discussion: https://postgr.es/m/a0b8026459d1e6167933be2104a6174e7d40d0ab.camel%40j-davis.com#fe7218c83b08068bfffb0c5293eceda0
Author: Paul Jungwirth, revised by me
Reviewed-by: David Fetter, Corey Huinker, Jeff Davis, Pavel Stehule
Reviewed-by: Alvaro Herrera, Tom Lane, Isaac Morland, David G. Johnston
Reviewed-by: Zhihong Yu, Alexander Korotkov

Commit 257836a7 added the "locale" subdirectory to SUBDIRS,
but neglected to remove it from ALWAYS_SUBDIRS.  This oversight
had no functional effect because the filter-out function would
remove it anyway.  Still, it's confusing to readers to list a
subdirectory in both places, especially because it makes the
associated comment into a partial lie.

The comments atop of this function describes behaviour in case of a
transactional WAL message only, but it accepts both transactional and
non-transactional WAL messages. Update the comments to describe
behaviour in case of non-transactional WAL message as well.

Ashutosh Bapat, rephrased by Amit Kapila
Discussion: https://postgr.es/m/CAGEoWWTTzNzHOi8bj0wfAo1siGi-YEh6wqH1oaz4DrkTJ6HbTQ@mail.gmail.com

Any subdirectory that's ignoring /output_iso/ should also
ignore /tmp_check_iso/, which could be left behind by a
failed pg_isolation_regress_check run.

I think these have been wrong for awhile, but it doesn't
seem important to fix in back branches.

A narrow reading of the C standard says that memcpy(x,x,n) is undefined,
although it's hard to envision an implementation that would really
misbehave.  However, analysis tools such as valgrind might whine about
this; accordingly, let's band-aid relmapper.c to not do it.

See also 5b630501, d3f4e8a8, ad7b48ea, and other similar fixes.
Apparently, none of those folk tried valgrinding initdb?  This has been
like this for long enough that I'm surprised it hasn't been reported
before.

Back-patch, just in case anybody wants to use a back branch on a platform
that complains about this; we back-patched those earlier fixes too.

Discussion: https://postgr.es/m/161790.1608310142@sss.pgh.pa.us

This commit adds "stats_reset" column into the pg_stat_statements_info
view. This column indicates the time at which all statistics in the
pg_stat_statements view were last reset.

Per discussion, this commit also changes pg_stat_statements_info code
so that "dealloc" column is reset at the same time as "stats_reset" is reset,
i.e., whenever all pg_stat_statements entries are removed, for the sake
of consistency. Previously "dealloc" was reset only when
pg_stat_statements_reset(0, 0, 0) is called and was not reset when
pg_stat_statements_reset() with non-zero value argument discards all
entries. This was confusing.

Author: Naoki Nakamichi, Yuki Seino
Reviewed-by: Yuki Seino, Kyotaro Horiguchi, Li Japin, Fujii Masao
Discussion: https://postgr.es/m/c102cf3180d0ee73c1c5a0f7f8558322@oss.nttdata.com

Revert ac22929a, as well as the followup fix 113d3591. Because it broke
the assumption that the startup process waiting for the recovery conflict
on buffer pin should be waken up only by buffer unpin or the timeout enabled
in ResolveRecoveryConflictWithBufferPin(). It caused, for example,
SIGHUP signal handler or walreceiver process to wake that startup process
up unnecessarily frequently.

Additionally, add the comments about why that dedicated latch that
the reverted patch tried to get rid of should not be removed.

Thanks to Kyotaro Horiguchi for the discussion.

Author: Fujii Masao
Discussion: https://postgr.es/m/d8c0c608-021b-3c73-fffd-3240829ee986@oss.nttdata.com

Seems to be a copy-and-pasteo in c06d6aa4.  Per buildfarm.

Offsets are shown as NULL only for anonymous allocations.

Author: Benoit Lobréau
Reviewed-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/CAPE8EZ5Lnoyqoz7aZpvQM0E8sW+hw+k6G2NULe+m4arFRrA1aA@mail.gmail.com
Backpatch-through: 13

It was not clear how COPY TO behaved with partitioning/inheritance
because the paragraphs were so far apart.  Also reword to simplify.

Discussion: https://postgr.es/m/20201203211723.GR24052@telsasoft.com

Author: Justin Pryzby

Backpatch-through: 10

"Ordering stuff" refered to a _bt_first() call to _bt_orderkeys().
However, the _bt_orderkeys() function was renamed to
_bt_preprocess_keys() by commit fa5c8a05.

_bt_preprocess_keys() is directly referenced just after the removed
comment already, which seems sufficient.

Mistakenly introduced in 4cbe3ac3; bug repaired in 148e632c but
the stores were accidentally.

To build Gather Merge path, the input needs to be sufficiently sorted.
Ensuring this is the responsibility of the code constructing the paths,
but create_gather_merge_plan tried to handle unsorted paths by adding
an explicit Sort. In light of the recent issues related to Incremental
Sort, this is rather fragile. Some of the expressions may be volatile
or parallel unsafe, in which case we can't add the Sort here.

We could do more checks and add the Sort in at least some cases, but
it seems cleaner to just error out and make it clear this is a bug in
code constructing those paths.

Author: James Coleman
Reviewed-by: Tomas Vondra
Discussion: https://postgr.es/m/CAAaqYe8cK3g5CfLC4w7bs%3DhC0mSksZC%3DH5M8LSchj5e5OxpTAg%40mail.gmail.com
Discussion: https://postgr.es/m/CAJGNTeNaxpXgBVcRhJX%2B2vSbq%2BF2kJqGBcvompmpvXb7pq%2BoFA%40mail.gmail.com

Many older tests where written in a style like

    SELECT '' AS two, i.* FROM INT2_TBL

where the first column indicated the number of expected result rows.
This has gotten increasingly out of date, as the test data fixtures
have expanded, so a lot of these were wrong and misleading.  Moreover,
this style isn't really necessary, since the psql output already shows
the number of result rows.

To clean this up, remove all those extra columns.

Discussion: https://www.postgresql.org/message-id/flat/1a25312b-2686-380d-3c67-7a69094a999f%40enterprisedb.com

Invent a new flag bit HASH_STRINGS to specify C-string hashing, which
was formerly the default; and add assertions insisting that exactly
one of the bits HASH_STRINGS, HASH_BLOBS, and HASH_FUNCTION be set.
This is in hopes of preventing recurrences of the type of oversight
fixed in commit a1b8aa1e (i.e., mistakenly omitting HASH_BLOBS).

Also, when HASH_STRINGS is specified, insist that the keysize be
more than 8 bytes.  This is a heuristic, but it should catch
accidental use of HASH_STRINGS for integer or pointer keys.
(Nearly all existing use-cases set the keysize to NAMEDATALEN or
more, so there's little reason to think this restriction should
be problematic.)

Tweak hash_create() to insist that the HASH_ELEM flag be set, and
remove the defaults it had for keysize and entrysize.  Since those
defaults were undocumented and basically useless, no callers
omitted HASH_ELEM anyway.

Also, remove memset's zeroing the HASHCTL parameter struct from
those callers that had one.  This has never been really necessary,
and while it wasn't a bad coding convention it was confusing that
some callers did it and some did not.  We might as well save a few
cycles by standardizing on "not".

Also improve the documentation for hash_create().

In passing, improve reinit.c's usage of a hash table by storing
the key as a binary Oid rather than a string; and, since that's
a temporary hash table, allocate it in CurrentMemoryContext for
neatness.

Discussion: https://postgr.es/m/590625.1607878171@sss.pgh.pa.us

This reverts commit 3a9e64aa.

Commit 4bad60e3 fixed the root of the problem that 3a9e64aa worked
around.

This enables proper pipelining of commands after terminating
replication, eliminating an undocumented limitation.

Discussion: https://postgr.es/m/3d57bc29-4459-578b-79cb-7641baf53c57%40iki.fi
Backpatch-through: 9.5

This adjusts some code related to recent changes for cryptohash
functions:
- Add a variable in md5.h to track down the size of a computed result,
moved from pgcrypto.  Note that pg_md5_hash() assumed a result of this
size already.
- Call explicit_bzero() on the hashed data when freeing the context for
fallback implementations.  For MD5, particularly, it would be annoying
to leave some non-zeroed data around.
- Clean up some code related to recent changes of uuid-ossp.  .gitignore
still included md5.c and a comment was incorrect.

Discussion: https://postgr.es/m/X9HXKTgrvJvYO7Oh@paquier.xyz

This is done for end-of-recovery and shutdown checkpoints/restartpoints
(end-of-recovery restartpoints don't exist) rather than all types of
checkpoints, in cases where it may not be possible to rely on
pg_stat_activity to get a status from the startup or checkpointer
processes.

For example, at the end of a crash recovery, this is useful to know if a
checkpoint is running in the startup process, while previously the ps
display may only show some information about "recovering" something,
that can be confusing while a checkpoint runs.

Author: Justin Pryzby
Reviewed-by: Nathan Bossart, Kirk Jamison, Fujii Masao, Michael Paquier
Discussion: https://postgr.es/m/20200818225238.GP17022@telsasoft.com

This caused BufFile errors on buildfarm member sungazer, and SIGSEGV was
possible.  Conditions for reaching those symptoms were more frequent on
big-endian systems.

Discussion: https://postgr.es/m/20201129214441.GA691200@rfd.leadboat.com

Backpatch-through: 9.5

Backpatch-through: 9.5

This is basically a finger exercise to prove that it's possible for
an extension module to add subscripting ability.  Subscripted fetch
from an hstore is not different from the existing "hstore -> text"
operator.  Subscripted update does seem to be a little easier to
use than the traditional update method using hstore concatenation,
but it's not a fundamentally new ability.

However, there may be some value in the code as sample code, since
it shows what's basically the minimum-complexity way to implement
subscripting when one needn't consider nested container objects.

Discussion: https://postgr.es/m/3724341.1607551174@sss.pgh.pa.us

This is essential if we'd like to allow existing extension data types
to support subscripting in future, since dropping and recreating the
type isn't a practical thing for an extension upgrade script, and
direct manipulation of pg_type isn't a great answer either.

There was some discussion about also allowing alteration of typelem,
but it's less clear whether that's a good idea or not, so for now
I forebore.

Discussion: https://postgr.es/m/3724341.1607551174@sss.pgh.pa.us

Commit c7aba7c1 didn't add this, but after more fooling with the
feature I feel that it'd be useful.  To make this possible, refactor
getSubscriptingRoutines() so that the caller is responsible for
throwing any error.  (In clauses.c, I just chose to make the
most conservative assumption rather than throwing an error.  We don't
expect failures there anyway really, so the code space for an error
message would be a poor investment.)

This usage would mean that values of the enum type are potentially not
one of the enum values.  Use macros instead, like everywhere else.

Discussion: https://www.postgresql.org/message-id/14dde730-1d34-260e-fa9d-7664df2d6313@enterprisedb.com

This module had a dependency on pgcrypto's md5.c that got removed by
b67b57a9.  Instead of the code from pgcrypto, this code can just use the
new cryptohash routines for MD5 as a drop-in replacement, so let's just
do this switch.  This has also the merit to simplify a bit the
compilation of uuid-ossp.

This requires --with-uuid to be reproduced, and I have used e2fs as a
way to reproduce the failure, then test this commit.

Per reports from buildfarm members longfin, florican and sifaka.

Discussion: https://postgr.es/m/X9GToVd3QmWeNvj8@paquier.xyz