This command declares a SQL identifier for a SQL statement to be used in other
embedded SQL statements. The identifier is linked to a connection.

Author: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Reviewed-by: Shawn Wang <shawn.wang.pg@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/TY2PR01MB24438A52DB04E71D0E501452F5630@TY2PR01MB2443.jpnprd01.prod.outlook.com

Reported-by: John Naylor <john.naylor@enterprisedb.com>

Reported-by: Erik Rijkers <er@xs4all.nl>

Common recommendations are that the checkpoint should be spread out as
much as possible, provided we avoid having it take too long.  This
change updates the default to 0.9 (from 0.5) to match that
recommendation.

There was some debate about possibly removing the option entirely but it
seems there may be some corner-cases where having it set much lower to
try to force the checkpoint to be as fast as possible could result in
fewer periods of time of reduced performance due to kernel flushing.
General agreement is that the "spread more" is the preferred approach
though and those who need to tune away from that value are much less
common.

Reviewed-By: Michael Paquier, Peter Eisentraut, Tom Lane, David Steele,
Nathan Bossart
Discussion: https://postgr.es/m/20201207175329.GM16415%40tamriel.snowman.net

Change the default_toast_compression GUC to be an enum rather than
a string. Earlier, uncommitted versions of the patch supported using
CREATE ACCESS METHOD to add new compression methods to a running
system, but that idea was dropped before commit. So, we can simplify
the GUC handling as well, which has the nice side effect of improving
the error messages.

While updating the documentation to reflect the new GUC type, also
move it back to the right place in the list. I moved this while
revising what became commit 24f0e395,
but apparently the intended ordering is "alphabetical" rather than
"whatever Robert thinks looks nice."

Rejigger things to avoid having access/toast_compression.h depend on
utils/guc.h, so that we don't end up with every file that includes
it also depending on something largely unrelated. Move a few
inline functions back into the C source file partly to help reduce
dependencies and partly just to avoid clutter. A few very minor
cosmetic fixes.

Original patch by Justin Pryzby, but very heavily edited by me,
and reverse reviewed by him and also reviewed by by Tom Lane.

Discussion: http://postgr.es/m/CA+TgmoYp=GT_ztUCeZg2i4hkHAQv8o=-nVJ1-TKWTG1zQOmOpg@mail.gmail.com

Similar to date_trunc, but allows binning by an arbitrary interval
rather than just full units.

Author: John Naylor <john.naylor@enterprisedb.com>
Reviewed-by: David Fetter <david@fetter.org>
Reviewed-by: Isaac Morland <isaac.morland@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Artur Zakirov <zaartur@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CACPNZCt4buQFRgy6DyjuZS-2aPDpccRkrJBmgUfwYc1KiaXYxg@mail.gmail.com

Make it the same as another nearby message.

To allow inserts in parallel-mode this feature has to ensure that all the
constraints, triggers, etc. are parallel-safe for the partition hierarchy
which is costly and we need to find a better way to do that. Additionally,
we could have used existing cached information in some cases like indexes,
domains, etc. to determine the parallel-safety.

List of commits reverted, in reverse chronological order:

ed62d373 Doc: Update description for parallel insert reloption.
c8f78b61 Add a new GUC and a reloption to enable inserts in parallel-mode.
c5be48f0 Improve FK trigger parallel-safety check added by 05c8482f.
e2cda3c2 Fix use of relcache TriggerDesc field introduced by commit 05c8482f.
e4e87a32 Fix valgrind issue in commit 05c8482f.
05c8482f Enable parallel SELECT for "INSERT INTO ... SELECT ...".

Discussion: https://postgr.es/m/E1lMiB9-0001c3-SY@gemulon.postgresql.org

Commit de829ddf added wait event WalrcvExit. But its name is not
consistent with other wait events like WalReceiverMain or
WalReceiverWaitStart, etc. So this commit renames WalrcvExit to
WalReceiverExit.

Author: Fujii Masao
Reviewed-by: Thomas Munro
Discussion: https://postgr.es/m/cced9995-8fa2-7b22-9d91-3f22a2b8c23c@oss.nttdata.com

GetNewOidWithIndex() generates a new OID one by one until it finds
one not in the relation. If there are very long runs of consecutive
existing OIDs, GetNewOidWithIndex() needs to iterate many times
in the loop to find unused OID. Since TOAST table can have a large
number of entries and there can be such long runs of OIDs, there is
the case where it takes so many iterations to find new OID not in
TOAST table. Furthermore if all (i.e., 2^32) OIDs are already used,
GetNewOidWithIndex() enters something like busy loop and repeats
the iterations until at least one OID is marked as unused.

There are some reported troubles caused by a large number of
iterations in GetNewOidWithIndex(). For example, when inserting
a billion of records into the table, all the backends doing that
insertion operation got hang with 100% CPU usage at some point.

Previously there was no easy way to detect that GetNewOidWithIndex()
failed to find unused OID many times. So, for example, gdb full
backtrace of hanged backends needed to be taken, in order to
investigate that trouble. This is inconvenient and may not be
available in some production environments.

To provide easy way for that, this commit makes GetNewOidWithIndex()
log that it iterates more than GETNEWOID_LOG_THRESHOLD but have
not yet found OID unused in the relation. Also this commit makes
it repeat logging with exponentially increasing intervals until
it iterates more than GETNEWOID_LOG_MAX_INTERVAL, and makes it
finally repeat logging every GETNEWOID_LOG_MAX_INTERVAL unless
an unused OID is found. Those macro variables are used not to
fill up the server log with the similar messages.

In the discusion at pgsql-hackers, there was another idea to report
the lots of iterations in GetNewOidWithIndex() via wait event.
But since GetNewOidWithIndex() traverses indexes to find unused
OID and which will do I/O, acquire locks, etc, which will overwrite
the wait event and reset it to nothing once done. So that idea
doesn't work well, and we didn't adopt it.

Author: Tomohiro Hiramitsu
Reviewed-by: Tatsuhito Kasahara, Kyotaro Horiguchi, Tom Lane, Fujii Masao
Discussion: https://postgr.es/m/16722-93043fb459a41073@postgresql.org

Using "remain" is confusing, as it implies that the index file can
shrink.  Instead, use "in total".

Per discussion with Peter Geoghegan.

Discussion: https://postgr.es/m/CAH2-WzkYgHZzpGOwR14CScJsjaQpvJrEkEfkh_=wGhzLb=yVdQ@mail.gmail.com

When resolving types during catalog bootstrap, try to reload the pg_type
contents if a type is not found. That allows catalogs to contain
composite types, e.g. row types for other catalogs.

Author: Justin Pryzby
Reviewed-by: Dean Rasheed, Tomas Vondra
Discussion: https://postgr.es/m/ad7891d2-e90c-b446-9fe2-7419143847d7%40enterprisedb.com

It's a bit easier and more convenient to free and reload a List,
compared to a plain array. This will be helpful when allowing catalogs
to contain composite types.

Author: Justin Pryzby
Reviewed-by: Dean Rasheed, Tomas Vondra
Discussion: https://postgr.es/m/ad7891d2-e90c-b446-9fe2-7419143847d7%40enterprisedb.com

Teach nbtree VACUUM to press on with vacuuming in the event of a page
deletion attempt that fails to "re-find" a downlink for its child/target
page.

There is no good reason to treat this as an irrecoverable error.  But
there is a good reason not to: pressing on at this point removes any
question of VACUUM not making progress solely due to misbehavior from
user-defined operator class code.

Discussion: https://postgr.es/m/CAH2-Wzma5G9CTtMjbrXTwOym+U=aWg-R7=-htySuztgoJLvZXg@mail.gmail.com

Disable autovacuum, because we don't want it to run against
intentionally corrupted tables. Also, before corrupting the tables,
run pg_amcheck and ensure that it passes. Otherwise, if something
unexpected happens when we check the corrupted tables, it's not so
clear whether it would have also happened before we corrupted
them.

Mark Dilger

Discussion: http://postgr.es/m/AA5506CE-7D2A-42E4-A51D-358635E3722D@enterprisedb.com

Jasen Betts reported yet another unintended side effect of commit
85c54287: reconnecting with "\c service=whatever" did not have the
expected results.  The reason is that starting from the output of
PQconndefaults() effectively allows environment variables (such
as PGPORT) to override entries in the service file, whereas the
normal priority is the other way around.

Not using PQconndefaults at all would require yet a third main code
path in do_connect's parameter setup, so I don't really want to fix
it that way.  But we can have the logic effectively ignore all the
default values for just a couple more lines of code.

This patch doesn't change the behavior for "\c -reuse-previous=on
service=whatever".  That remains significantly different from before
85c54287, because many more parameters will be re-used, and thus
not be possible for service entries to replace.  But I think this
is (mostly?) intentional.  In any case, since libpq does not report
where it got parameter values from, it's hard to do differently.

Per bug #16936 from Jasen Betts.  As with the previous patches,
back-patch to all supported branches.  (9.5 is unfortunately now
out of support, so this won't get fixed there.)

Discussion: https://postgr.es/m/16936-3f524322a53a29f0@postgresql.org

end_heap_rewrite was not careful to ensure that the target relation
is open at the smgr level before performing its final smgrimmedsync.
In ordinary cases this is no problem, because it would have been
opened earlier during the rewrite.  However a crash can be reproduced
by re-clustering an empty table with CLOBBER_CACHE_ALWAYS enabled.

Although that exact scenario does not crash in v13, I think that's
a chance result of unrelated planner changes, and the problem is
likely still reachable with other test cases.  The true proximate
cause of this failure is commit c6b92041, which replaced a call to
heap_sync (which was careful about opening smgr) with a direct call
to smgrimmedsync.  Hence, back-patch to v13.

Amul Sul, per report from Neha Sharma; cosmetic changes
and test case by me.

Discussion: https://postgr.es/m/CANiYTQsU7yMFpQYnv=BrcRVqK_3U3mtAzAsJCaqtzsDHfsUbdQ@mail.gmail.com

This has previously not been a problem (that anyone ever reported),
but in future OpenSSL versions (3.0.0), where legacy ciphers are/can
be disabled, this is the place where this is reported.  So we need to
catch the error here, otherwise the higher-level functions would
return garbage.  The nearby encryption code already handled errors
similarly.
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://www.postgresql.org/message-id/9e9c431c-0adc-7a6d-9b1a-915de1ba3fe7@enterprisedb.com

This function for bit and bytea counts the set bits in the bit or byte
string.  Internally, we use the existing popcount functionality.

For the name, after some discussion, we settled on bit_count, which
also exists with this meaning in MySQL, Java, and Python.

Author: David Fetter <david@fetter.org>
Discussion: https://www.postgresql.org/message-id/flat/20201230105535.GJ13234@fetter.org

Once a relation's autovacuum is completed, the logs include more
information about this relation state if the threshold of
log_autovacuum_min_duration (or its relation option) is reached, with
for example contents about the statistics of the VACUUM operation for
the relation, WAL and system usage.

This commit adds more information about the statistics of the relation's
indexes, with one line of logs generated for each index.  The index
stats were already calculated, but not printed in the context of
autovacuum yet.  While on it, some refactoring is done to keep track of
the index statistics directly within LVRelStats, simplifying some
routines related to parallel VACUUMs.

Author: Masahiko Sawada
Reviewed-by: Michael Paquier, Euler Taveira
Discussion: https://postgr.es/m/CAD21AoAy6SxHiTivh5yAPJSUE4S=QRPpSZUdafOSz0R+fRcM6Q@mail.gmail.com

We can't access the entry after it is removed from dynahash.

Author: Peter Smith
Discussion: https://postgr.es/m/CAHut+Ps-pL++f6CJwPx2+vUqXuew=Xt-9Bi-6kCyxn+Fwi2M7w@mail.gmail.com

A couple error messages and comments used 'statistic kind', not the
correct 'statistics kind'. Fix and backpatch all the way back to 10,
where extended statistics were introduced.

Backpatch-through: 10

Previously the type of this wait event was Client. But while this
wait event is being reported, walreceiver process is waiting for
the startup process to set initial data for streaming replication.
It's not waiting for any activity on a socket connected to a user
application or walsender. So this commit changes the type for
WalReceiverWaitStart wait event to IPC.

Author: Fujii Masao
Reviewed-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/cdacc27c-37ff-f1a4-20e2-ce19933abfcc@oss.nttdata.com

pg_waldump --stats=record identifies a record by a combination
of the RmgrId and the four bits of the xl_info field of the record.
But XACT records use the first bit of those four bits for an optional
flag variable, and the following three bits for the opcode to
identify a record. So previously the same type of XACT record
could have different four bits (three bits are the same but the
first one bit is different), and which could cause
pg_waldump --stats=record to show two lines of per-record statistics
for the same XACT record. This is a bug.

This commit changes pg_waldump --stats=record so that it processes
only XACT record differently, i.e., filters the opcode out of xl_info
and uses a combination of the RmgrId and those three bits as
the identifier of a record, only for XACT record. For other records,
the four bits of the xl_info field are still used.

Back-patch to all supported branches.

Author: Kyotaro Horiguchi
Reviewed-by: Shinya Kato, Fujii Masao
Discussion: https://postgr.es/m/2020100913412132258847@highgo.ca

Previously, to check relation permanence, the Relation's Form_pg_class
structure member relpersistence was compared to the value
RELPERSISTENCE_PERMANENT ("p"). This commit adds the macro
RelationIsPermanent() and is used in appropirate places to simplify the
code.  This matches other RelationIs* macros.

This macro will be used in more places in future cluster file encryption
patches.

Discussion: https://postgr.es/m/20210318153134.GH20766@tamriel.snowman.net

The bringetbitmap function allocates memory for various purposes, which
may be quite expensive, depending on the number of scan keys. Instead of
allocating them separately, allocate one bit chunk of memory an carve it
into smaller pieces as needed - all the pieces have the same lifespan,
and it saves quite a bit of CPU and memory overhead.

Author: Tomas Vondra <tomas.vondra@postgresql.org>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Mark Dilger <hornschnorter@gmail.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Masahiko Sawada <masahiko.sawada@enterprisedb.com>
Reviewed-by: John Naylor <john.naylor@enterprisedb.com>
Discussion: https://postgr.es/m/c1138ead-7668-f0e1-0638-c3be3237e812@2ndquadrant.com

The handling of IS [NOT] NULL clauses is independent of an opclass, and
most of the code was exactly the same in both minmax and inclusion. So
instead move the code from support procedures to the AM.

This simplifies the code - especially the support procedures - quite a
bit, as they don't need to care about NULL values and flags at all. It
also means the IS [NOT] NULL clauses can be evaluated without invoking
the support procedure.

Author: Tomas Vondra <tomas.vondra@postgresql.org>
Author: Nikita Glukhov <n.gluhov@postgrespro.ru>
Reviewed-by: Nikita Glukhov <n.gluhov@postgrespro.ru>
Reviewed-by: Mark Dilger <hornschnorter@gmail.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Masahiko Sawada <masahiko.sawada@enterprisedb.com>
Reviewed-by: John Naylor <john.naylor@enterprisedb.com>
Discussion: https://postgr.es/m/c1138ead-7668-f0e1-0638-c3be3237e812@2ndquadrant.com

This commit changes how we pass scan keys to BRIN consistent function.
Instead of passing them one by one, we now pass all scan keys for a
given attribute at once. That makes the consistent function a bit more
complex, as it has to loop through the keys, but it does allow more
elaborate opclasses that can use multiple keys to eliminate ranges much
more effectively.

The existing BRIN opclasses (minmax, inclusion) don't really benefit
from this change. The primary purpose is to allow future opclases to
benefit from seeing all keys at once.

This does change the BRIN API, because the signature of the consistent
function changes (a new parameter with number of scan keys). So this
breaks existing opclasses, and will require supporting two variants of
the code for different PostgreSQL versions. We've considered supporting
two variants of the consistent, but we've decided not to do that.
Firstly, there's another patch that moves handling of NULL values from
the opclass, which means the opclasses need to be updated anyway.
Secondly, we're not aware of any out-of-core BRIN opclasses, so it does
not seem worth the extra complexity.

Bump catversion, because of pg_proc changes.

Author: Tomas Vondra <tomas.vondra@postgresql.org>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Mark Dilger <hornschnorter@gmail.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: John Naylor <john.naylor@enterprisedb.com>
Reviewed-by: Nikita Glukhov <n.gluhov@postgrespro.ru>
Discussion: https://postgr.es/m/c1138ead-7668-f0e1-0638-c3be3237e812@2ndquadrant.com

Until now the bsearch_arg function was used only in extended statistics
code, so it was defined in that code.  But we already have qsort_arg in
src/port, so let's move it next to it.

substring(), and perhaps other callers, isn't careful to pass a
slice length that is no more than the datum's true size.  Since
toast_decompress_datum_slice's children will palloc the requested
slice length, this can waste memory.  Also, close study of the liblz4
documentation suggests that it is dependent on the caller to not ask
for more than the correct amount of decompressed data; this squares
with observed misbehavior with liblz4 1.8.3.  Avoid these problems
by switching to the normal full-decompression code path if the
slice request is >= datum's decompressed size.

Tom Lane and Dilip Kumar

Discussion: https://postgr.es/m/507597.1616370729@sss.pgh.pa.us

The authors of bbe0a81d hadn't quite got the idea that macros named
like SOMETHING_4B_C were only meant for internal endianness-related
details in postgres.h.  Choose more legible names for macros that are
intended to be used elsewhere.  Rearrange postgres.h a bit to clarify
the separation between those internal macros and ones intended for
wider use.

Also, avoid using the term "rawsize" for true decompressed size;
we've used "extsize" for that, because "rawsize" generally denotes
total Datum size including header.  This choice seemed particularly
unfortunate in tests that were comparing one of these meanings to
the other.

This patch includes a couple of not-purely-cosmetic changes: be
sure that the shifts aligning compression methods are unsigned
(not critical today, but will be when compression method 2 exists),
and fix broken definition of VARATT_EXTERNAL_GET_COMPRESSION (now
VARATT_EXTERNAL_GET_COMPRESS_METHOD), whose callers worked only
accidentally.

Discussion: https://postgr.es/m/574197.1616428079@sss.pgh.pa.us

This seems to have been just copied-and-pasted from some other
header checks.  But our C code is entirely unprepared to support
such a header name, so it's only wasting cycles to look for it.
If we did need to support it, some #ifdefs would be required.

(A quick trawl at codesearch.debian.net finds some packages that
reference lz4/lz4.h; but they use *only* that spelling, and
appear to be intending to reference their own copy rather than
a system-level installation of liblz4.  There's no evidence of
freestanding installations that require this spelling.)

Discussion: https://postgr.es/m/457962.1616362509@sss.pgh.pa.us

The previous coding treated an invalid compression method name as
equivalent to the default, which is certainly not right.

Justin Pryzby

Discussion: http://postgr.es/m/20210321235544.GD4203@telsasoft.com

Previously, the default_toast_compression GUC was not documented,
and neither was pg_dump's new --no-toast-compression option.

Justin Pryzby and Robert Haas

Discussion: http://postgr.es/m/20210321235544.GD4203@telsasoft.com

Remove unused macro. Fix confusion about whether a TOAST compression
method is identified by an OID or a char.

Justin Pryzby

Discussion: http://postgr.es/m/20210321235544.GD4203@telsasoft.com

This commit is mostly a revert of aaa3aedd, that switched the routine
doing the internal renaming of recycled WAL segments to use on Windows a
combination of CreateHardLinkA() plus unlink() instead of rename().  As
reported by several users of Postgres 13, this is causing concurrency
issues when manipulating WAL segments, mostly in the shape of the
following error:
LOG:  could not rename file "pg_wal/000000XX000000YY000000ZZ":
Permission denied

This moves back to a logic where a single rename() (well, pgrename() for
Windows) is used.  This issue has proved to be hard to hit when I tested
it, facing it only once with an archive_command that was not able to do
its work, so it is environment-sensitive.  The reporters of this issue
have been able to confirm that the situation improved once we switched
back to a single rename().  In order to check things, I have provided to
the reporters a patched build based on 13.2 with aaa3aedd reverted, to
test if the error goes away, and an unpatched build of 13.2 to test if
the error still showed up (just to make sure that I did not mess up my
build process).

Extra thanks to Fujii Masao for pointing out what looked like the
culprit commit, and to all the reporters for taking the time to test
what I have sent them.

Reported-by: Andrus, Guy Burgess, Yaroslav Pashinsky, Thomas Trenz
Reviewed-by: Tom Lane, Andres Freund
Discussion: https://postgr.es/m/3861ff1e-0923-7838-e826-094cc9bef737@hot.ee
Discussion: https://postgr.es/m/16874-c3eecd319e36a2bf@postgresql.org
Discussion: https://postgr.es/m/095ccf8d-7f58-d928-427c-b17ace23cae6@burgess.co.nz
Discussion: https://postgr.es/m/16927-67c570d968c99567%40postgresql.org
Discussion: https://postgr.es/m/YFBcRbnBiPdGZvfW@paquier.xyz
Backpatch-through: 13

This commit improves pgbench \sleep command so that it handles
the following three cases more properly.

(1) When only one argument was specified in \sleep command and
    it's not a number, previously pgbench reported a confusing error
    message like "unrecognized time unit, must be us, ms or s".
    This commit fixes this so that more proper error message like
    "invalid sleep time, must be an integer" is reported.

(2) When two arguments were specified in \sleep command and
    the first argument was not a number, previously pgbench treated
    that argument as the sleep time 0. No error was reported in this
    case. This commit fixes this so that an error is thrown in this
    case.

(3) When a variable was specified as the first argument in \sleep
    command and the variable stored non-digit value, previously
    pgbench treated that argument as the sleep time 0. No error
    was reported in this case. This commit fixes this so that
    an error is thrown in this case.

Author: Kota Miyake
Reviewed-by: Hayato Kuroda, Alvaro Herrera, Fujii Masao
Discussion: https://postgr.es/m/23b254daf20cec4332a2d9168505dbc9@oss.nttdata.com

Back-patch to v13, which introduced the test code in question.

The test added by 595b9cba forgot that on Windows it is necessary to set
up pg_hba.conf (see PostgresNode::set_replication_conf) with a specific
entry or base backups fail.  Any node that requires to support
replication just needs to pass down allows_streaming at initialization.
This updates the test to do so.  Simplify things a bit while on it.

Per buildfarm member fairywren.  Any Windows hosts running this test
would have failed, and I have reproduced the problem as well.

Backpatch-through: 10

The TAP tests of kerberos rely on the logs generated by the backend to
check various connection scenarios.  In order to make sure that a given
test does not overlap with the log contents generated by a previous
test, the test suite relied on a logic with the logging collector and a
rotation of the log files to ensure the uniqueness of the log generated
with a wait phase.

Parsing the log contents for expected patterns is a problem that has
been solved in a simpler way by PostgresNode::issues_sql_like() where
the log file is truncated before checking for the contents generated,
with the backend sending its output to a log file given by pg_ctl
instead.  This commit switches the kerberos test suite to use such a
method, removing any wait phase and simplifying the whole logic,
resulting in less code.  If a failure happens in the tests, the contents
of the logs are still showed to the user at the moment of the failure
thanks to like(), so this has no impact on debugging capabilities.

I have bumped into this issue while reviewing a different patch set
aiming at extending the kerberos test suite to check for multiple
log patterns instead of one now.

Author: Michael Paquier
Reviewed-by: Stephen Frost, Bharath Rupireddy
Discussion: https://postgr.es/m/YFXcq2vBTDGQVBNC@paquier.xyz