There was some confusion around how to adjust the n_distinct estimates
for partitioned tables. Here we try and clarify that
n_distinct_inherited needs to be adjusted rather than n_distinct.
Also fix some slightly misleading text which was talking about table
size rather than table rows, fix a grammatical error, and adjust some
text which indicated that ANALYZE was performing calculations based on
the n_distinct settings. Really it's the query planner that does this
and ANALYZE only stores the overridden n_distinct estimate value in
pg_statistic.
Author: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: David G. Johnston <david.g.johnston@gmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Backpatch-through: 13
Discussion: https://postgr.es/m/CAApHDvrL7a-ZytM1SP8Uk9nEw9bR2CPzVb+uP+bcNj=_q-ZmVw@mail.gmail.com
Since protocol version 3.2 the CancelRequest does not have a fixed size
length anymore. The protocol docs still listed the length field to be a
constant number though. This fixes that.
Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Reported-by: Dmitry Igrishin <dmitigr@gmail.com>
Backpatch-through: 18
Remove stray whitespace in xref tag.
This was found due to a regression in xmllint 2.15.0 which flagged
this as an error, and at the time of this commit no fix for xmllint
has shipped.
Author: Erik Wienhold <ewie@ewie.name>
Discussion: https://postgr.es/m/f4c4661b-4e60-4c10-9336-768b7b55c084@ewie.name
Backpatch-through: 17
Remove stray whitespace in xref tag.
This was found due to a regression in xmllint 2.15.0 which flagged
this as an error, and at the time of this commit no fix for xmllint
has shipped.
Author: Erik Wienhold <ewie@ewie.name>
Discussion: https://postgr.es/m/f4c4661b-4e60-4c10-9336-768b7b55c084@ewie.name
Backpatch-through: 17
This reverts commit 98fc31d649.
That change allowed DROP OWNED BY to drop grants of the target
role to other roles, arguing that nobody would need those
privileges anymore. But that's not so: if you're not superuser,
you still need admin privilege on the target role so you can
drop it.
It's not clear whether or how the dependency-based approach
to solving the original problem can be adapted to keep these
grants. Since v18 release is fast approaching, the sanest
thing to do seems to be to revert this patch for now. The
race-condition problem is low severity and not worth taking
risks for.
I didn't force a catversion bump in 98fc31d64, so I won't do
so here either.
Reported-by: Dipesh Dhameliya <dipeshdhameliya125@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CABgZEgczOFicCJoqtrH9gbYMe_BV3Hq8zzCBRcMgmU6LRsihUA@mail.gmail.com
Backpatch-through: 18
If extensions of equal names were installed in different directories
in the path, the views pg_available_extensions and
pg_available_extension_versions would show all of them, even though
only the first one was actually reachable by CREATE EXTENSION. To
fix, have those views skip extensions found later in the path if they
have names already found earlier.
Also add a bit of documentation that only the first extension in the
path can be used.
Reported-by: Pierrick <pierrick.chovelon@dalibo.com>
Discussion: https://www.postgresql.org/message-id/flat/8f5a0517-1cb8-4085-ae89-77e7454e27ba%40dalibo.com
This section claims that each backend executes the
shmem_startup_hook shortly after attaching to shared memory, which
is true for EXEC_BACKEND builds, but not for others. This commit
adds this important detail.
Oversight in commit 964152c476.
Reported-by: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/CAA5RZ0vEGT1eigGbVt604LkXP6mUPMwPMxQoRCbFny44w%2B9EUQ%40mail.gmail.com
Backpatch-through: 17
When vacuumdb's --missing-stats-only option is used, the catalog
query for retrieving the list of relations to process must read
pg_statistic and pg_statistic_ext_data. However, those catalogs
can only be read by superusers by default, so --missing-stats-only
is effectively superuser-only. This is unfortunate, but since the
option is primarily intended for use by administrators after
running pg_upgrade, let's just live with it for v18. This commit
adds a note about the aforementioned privilege requirements to the
documentation for --missing-stats-only.
We first tried to improve matters by modifying the query to read
the pg_stats and pg_stats_ext system views instead. While that is
indeed more lenient from a privilege standpoint, it is also
borderline incomprehensible. pg_stats shows rows for which the
user has the SELECT privilege on the corresponding column, and
pg_stats_ext shows rows for tables the user owns. Meanwhile,
ANALYZE requires either MAINTAIN on the table or, for non-shared
relations, ownership of the database. But even if the privilege
discrepancies were tolerable, the performance impact was not.
Ultimately, the modified query was substantially more expensive, so
we abandoned the idea.
For v19, perhaps we could introduce a simple, inexpensive way to
discover which relations are missing statistics, such as a system
function or view with similar privilege requirements to ANALYZE.
Unfortunately, it is far too late for anything like that in v18.
Reviewed-by: Yugo Nagata <nagata@sraoss.co.jp>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/CAHGQGwHh43suEfss1wvBsk7vqiou%3DUY0zcy8HGyE5hBp%2BHZ7SQ%40mail.gmail.com
Backpatch-through: 18
The protocol documentation states that the maximum length of a cancel
key is 256 bytes. This starts checking for that limit in libpq.
Otherwise third party backend implementations will probably start
using more bytes anyway. We also start requiring that a protocol 3.0
connection does not send a longer cancel key, to make sure that
servers don't start breaking old 3.0-only clients by accident. Finally
this also restricts the minimum key length to 4 bytes (both in the
protocol spec and in the libpq implementation).
Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Reviewed-by: Jacob Champion <jchampion@postgresql.org>
Discussion: https://www.postgresql.org/message-id/df892f9f-5923-4046-9d6f-8c48d8980b50@iki.fi
Backpatch-through: 18
Temporary relations may share the same RelFileNumber with a permanent
relation, or other temporary relations associated with other sessions.
Being able to uniquely identify a temporary relation would require
RelidByRelfilenumber() to know about the proc number of the temporary
relation it wants to identify, something it is not designed for since
its introduction in f01d1ae3a1.
There are currently three callers of RelidByRelfilenumber():
- autoprewarm.
- Logical decoding, reorder buffer.
- pg_filenode_relation(), that attempts to find a relation OID based on
a tablespace OID and a RelFileNumber.
This makes the situation problematic particularly for the first two
cases, leading to the possibility of random ERRORs due to
inconsistencies that temporary relations can create in the cache
maintained by RelidByRelfilenumber(). The third case should be less of
an issue, as I suspect that there are few direct callers of
pg_filenode_relation().
The window where the ERRORs are happen is very narrow, requiring an OID
wraparound to create a lookup conflict in RelidByRelfilenumber() with a
temporary table reusing the same OID as another relation already cached.
The problem is easier to reach in workloads with a high OID consumption
rate, especially with a higher number of temporary relations created.
We could get pg_filenode_relation() and RelidByRelfilenumber() to work
with temporary relations if provided the means to identify them with an
optional proc number given in input, but the years have also shown that
we do not have a use case for it, yet. Note that this could not be
backpatched if pg_filenode_relation() needs changes. It is simpler to
ignore temporary relations.
Reported-by: Shenhao Wang <wangsh.fnst@fujitsu.com>
Author: Vignesh C <vignesh21@gmail.com>
Reviewed-By: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-By: Robert Haas <robertmhaas@gmail.com>
Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-By: Takamichi Osumi <osumi.takamichi@fujitsu.com>
Reviewed-By: Michael Paquier <michael@paquier.xyz>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Reported-By: Shenhao Wang <wangsh.fnst@fujitsu.com>
Discussion: https://postgr.es/m/bbaaf9f9-ebb2-645f-54bb-34d6efc7ac42@fujitsu.com
Backpatch-through: 13
The description of this GUC provides a list of the situations where
full-page writes are generated. However, it is not completely exact,
mentioning only the cases where full_page_writes=on or base backups. It
is possible to generate full-page writes in more situations than these
two, making the description confusing as it implies that no other cases
exist.
The description is slightly reworded to take into account that other
cases are possible, without mentioning them directly to minimize the
maintenance burden should FPWs be generated in more contexts in the
future.
Author: Jingtang Zhang <mrdrivingduck@gmail.com>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com>
Discussion: https://postgr.es/m/CAPsk3_CtAYa_fy4p6=x7qtoutrdKvg1kGk46D5fsE=sMt2546g@mail.gmail.com
Backpatch-through: 13
A malicious server could inject psql meta-commands into plain-text
dump output (i.e., scripts created with pg_dump --format=plain,
pg_dumpall, or pg_restore --file) that are run at restore time on
the machine running psql. To fix, introduce a new "restricted"
mode in psql that blocks all meta-commands (except for \unrestrict
to exit the mode), and teach pg_dump, pg_dumpall, and pg_restore to
use this mode in plain-text dumps.
While at it, encourage users to only restore dumps generated from
trusted servers or to inspect it beforehand, since restoring causes
the destination to execute arbitrary code of the source superusers'
choice. However, the client running the dump and restore needn't
trust the source or destination superusers.
Reported-by: Martin Rakhmanov
Reported-by: Matthieu Denais <litezeraw@gmail.com>
Reported-by: RyotaK <ryotak.mail@gmail.com>
Suggested-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Security: CVE-2025-8714
Backpatch-through: 13
Although the "Floating-Point Types" section says that "float" data
type is taken to mean "double precision", this information was not
reflected in the data type table that lists all data type aliases.
Reported-by: alexander.kjall@hafslund.no
Author: Euler Taveira <euler@eulerto.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/175456294638.800.12038559679827947313@wrigleys.postgresql.org
Backpatch-through: 13
Small touch-up on commits 25505082f0 and 50fd428b2b. Fix the
formatting of the example messages in the documentation and adjust the
wording to match the code.
ALTER TABLE ... SET EXPRESSION AS removes statistics for the target column,
so running ANALYZE afterward is recommended. But this was previously not
documented, even though a similar recommendation exists for
ALTER TABLE ... SET DATA TYPE, which also clears the column's statistics.
This commit updates the documentation to include the ANALYZE recommendation
for SET EXPRESSION AS.
Since v18, virtual generated columns are supported, and these columns never
have statistics. Therefore, ANALYZE is not needed after SET DATA TYPE or
SET EXPRESSION AS when used on virtual generated columns. This commit also
updates the documentation to clarify that ANALYZE is unnecessary in such cases.
Back-patch the ANALYZE recommendation for SET EXPRESSION AS to v17
where the feature was introduced, and the note about virtual generated
columns to v18 where those columns were added.
Author: Yugo Nagata <nagata@sraoss.co.jp>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/20250804151418.0cf365bd2855d606763443fe@sraoss.co.jp
Backpatch-through: 17
It's possible to use a CHECK (col IS NOT NULL) constraint to skip
scanning a table for nulls when adding a NOT NULL constraint on the same
column. However, if the CHECK constraint is dropped on the same command
that the NOT NULL is added, this fails, i.e., makes the NOT NULL addition
slow. The best we can do about it at this stage is to document this so
that users aren't taken by surprise.
(In Postgres 18 you can directly add the NOT NULL constraint as NOT
VALID instead, so there's no longer much use for the CHECK constraint,
therefore no point in building mechanism to support the case better.)
Reported-by: Andrew <psy2000usa@yahoo.com>
Reviewed-by: David G. Johnston <david.g.johnston@gmail.com>
Discussion: https://postgr.es/m/175385113607.786.16774570234342968908@wrigleys.postgresql.org
It was not very clear that the triggers are only allowed on plain tables
(not foreign tables). Also, rephrase the documentation for better
readability.
Follow up to commit 9e6104c66.
Reported-by: Etsuro Fujita <etsuro.fujita@gmail.com>
Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Etsuro Fujita <etsuro.fujita@gmail.com>
Discussion: https://postgr.es/m/CAPmGK16XBs9ptNr8Lk4f-tJZogf6y-Prz%3D8yhvJbb_4dpsc3mQ%40mail.gmail.com
Backpatch-through: 13
PostgreSQL always sends the BackendKeyData message at connection
startup, but there are some third party backend implementations out
there that don't support cancellation, and don't send the message
[1]. While the protocol docs left it up for interpretation if that is
valid behavior, libpq in PostgreSQL 17 and below accepted it. It does
not seem like the libpq behavior was intentional though, since it did
so by sending CancelRequest messages with all zeros to such servers
(instead of returning an error or making the cancel a no-op).
In version 18 the behavior was changed to return an error when trying
to create the cancel object with PGgetCancel() or PGcancelCreate().
This was done without any discussion, as part of supporting different
lengths of cancel packets for the new 3.2 version of the protocol.
This commit changes the behavior of PGgetCancel() / PGcancel() once
more to only return an error when the cancel object is actually used
to send a cancellation, instead of when merely creating the object.
The reason to do so is that some clients [2] create a cancel object as
part of their connection creation logic (thus having the cancel object
ready for later when they need it), so if creating the cancel object
returns an error, the whole connection attempt fails. By delaying the
error, such clients will still be able to connect to the third party
backend implementations in question, but when actually trying to
cancel a query, the user will be notified that that is not possible
for the server that they are connected to.
This commit only changes the behavior of the older PGgetCancel() /
PQcancel() functions, not the more modern PQcancelCreate() family of
functions. I.e. PQcancelCreate() returns a failed connection object
(CONNECTION_BAD) if the server didn't send a cancellation key. Unlike
the old PQgetCancel() function, we're not aware of any clients in the
field that use PQcancelCreate() during connection startup in a way
that would prevent connecting to such servers.
[1] AWS RDS Proxy is definitely one of them, and CockroachDB might be
another.
[2] psycopg2 (but not psycopg3).
Author: Jelte Fennema-Nio <postgres@jeltef.nl>
Reviewed-by: Jacob Champion <jacob.champion@enterprisedb.com>
Backpatch-through: 18
Discussion: https://www.postgresql.org/message-id/20250617.101056.1437027795118961504.ishii%40postgresql.org
The sentence in question gave readers the impression that vacuumdb
removes statistics for a period of time while analyzing, but it's
actually meant to convey that --analyze-in-stages temporarily
replaces existing statistics with ones generated with lower
statistics targets.
Reported-by: Frédéric Yhuel <frederic.yhuel@dalibo.com>
Reviewed-by: Frédéric Yhuel <frederic.yhuel@dalibo.com>
Reviewed-by: "David G. Johnston" <david.g.johnston@gmail.com>
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Reviewed-by: Jeff Davis <pgsql@j-davis.com>
Discussion: https://postgr.es/m/4b94ca16-7a6d-4581-b2aa-4ea79dbc082a%40dalibo.com
Backpatch-through: 18
Recent discussions of the mechanisms used to manage global data have
raised concerns about their robustness and security. Rather than try
to deal with those concerns at a very late stage of the release cycle,
the conclusion is to revert these features and work on them for the
next release.
This reverts parts or all of the following commits:
1495eff7bd Non text modes for pg_dumpall, correspondingly change pg_restore
5db3bf7391 Clean up from commit 1495eff7bd289f74d0cb Add more TAP tests for pg_dumpall
2ef5790806 Fix a couple of error messages and tests for them
b52a4a5f28 Clean up error messages from 1495eff7bd4170298b6e Further cleanup for directory creation on pg_dump/pg_dumpall
22cb6d2895 Fix memory leak in pg_restore.c
928394b664 Improve various new-to-v18 appendStringInfo calls
39729ec01d Fix fat fingering in 22cb6d28955822bf21d5 Add missing space in pg_restore documentation.
f09088a01d Free memory properly in pg_restore.c
40b9c27014 pg_restore cleanups
4aad2cb770 Portability fix: isdigit() must be passed an unsigned char.
88e947136b Fix typos and grammar in the code
f60420cff6 doc: Alphabetize long options for pg_dump[all].
bc35adee8d doc: Put new options in consistent order on man pages
a876464abc Message style improvements
dec6643487 Improve pg_dump/pg_dumpall help synopses and terminology
0ebd242555 Run pgperltidy
Discussion: https://postgr.es/m/20250708212819.09.nmisch@google.com
Backpatch-to: 18
Reviewed-by: Noah Misch <noah@leadboat.com>
This commit documents differences in the definition of word separators for
the initcap function between libc and ICU locale providers.
Backpatch to all supported branches.
Discussion: https://postgr.es/m/804cc10ef95d4d3b298e76b181fd9437%40postgrespro.ru
Author: Oleg Tselebrovskiy <o.tselebrovskiy@postgrespro.ru>
Backpatch-through: 13
This commit adds missing index entries for the functions pg_buffercache_numa()
and pg_buffercache_usage_counts() in the pg_buffercache documentation.
It also makes the function titles consistent by adding parentheses after
function names where they were previously missing.
Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/7d19af4b-7da3-4862-9f52-ff958960bd8d@oss.nttdata.com
Backpatch-through: 18
The definition of \dRp+ was modified in commit 7054186c4e. This patch
updates the column list and row filter examples to align with the revised
definition.
Author: Shlok Kyal <shlok.kyal.oss@gmail.com>
Reviewed by: Peter Smith <smithpb2250@gmail.com>
Backpatch-through: 18, where it was introduced
Discussion: https://postgr.es/m/CANhcyEUvqkSO6b9zi_fs_BBPEge5acj4mf8QKmq2TX-7axa7EQ@mail.gmail.com
This index AM callback has been introduced in c1ec02be1d and it is
optional, currently only being used by BRIN. Optional callbacks are
documented with NULL as possible value in amapi.h and indexam.sgml, but
this callback has missed this part of the description.
Reported-by: Peter Smith <smithpb2250@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Discussion: https://postgr.es/m/CAHut+PvgYcPmPDi1YdHMJY5upnyGRpc0N8pk1xNB11xDSBwNog@mail.gmail.com
Backpatch-through: 17
When pg_recvlogical receives a SIGHUP signal, it closes the current
output file and reopens a new one. This is useful since it allows us to
rotate the output file by renaming the current file and sending a SIGHUP.
This behavior was previously undocumented. This commit adds
the missing documentation.
Back-patch to all supported versions.
Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Shinya Kato <shinya11.kato@gmail.com>
Discussion: https://postgr.es/m/0977fc4f-1523-4ecd-8a0e-391af4976367@oss.nttdata.com
Backpatch-through: 13
This commit adds a note to the pg_overexplain page that describes
how to use it (LOAD, session_preload_libraries, or
shared_preload_libraries). The new text is mostly lifted from the
auto_explain page. We should probably consider centralizing this
information in the future.
While at it, add a missing "module" to the opening sentence.
Reviewed-by: "David G. Johnston" <david.g.johnston@gmail.com>
Reviewed-by: Robert Treat <rob@xzilla.net>
Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com>
Discussion: https://postgr.es/m/aHVWKM8l8kLlZzgv%40nathan
Backpatch-through: 18
The paragraph for introducing INSERT and COPY discussed how a file
could be used for bulk loading with COPY, without actually showing
what the file would look like. This adds a programlisting for the
file contents.
Backpatch to all supported branches since this example has lacked
the file contents since PostgreSQL 7.2.
Author: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Fujii Masao <masao.fujii@oss.nttdata.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/158017814191.19852.15019251381150731439@wrigleys.postgresql.org
Backpatch-through: 13
Previously, the documentation described the streaming option as a boolean,
which is outdated since it's no longer a boolean as of protocol version 4.
This could confuse users.
This commit updates the description to remove the "boolean" reference and
clearly list the valid values for the streaming option.
Back-patch to v16, where the streaming option changed to a non-boolean.
Author: Euler Taveira <euler@eulerto.com>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/8d21fb98-5c25-4dee-8387-e5a62b01ea7d@app.fastmail.com
Backpatch-through: 16
David Rowley