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
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
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
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 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
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
The last_vacuum and vacuum_count fields in pg_stat_all_tables already
state that they do not include VACUUM FULL. However, total_vacuum_time,
which also excludes VACUUM FULL, did not mention this. This could
mislead users into thinking VACUUM FULL time is included.
To address this, this commit updates the documentation for
pg_stat_all_tables to explicitly state that total_vacuum_time does not
count VACUUM FULL.
Back-patched to v18, where total_vacuum_time was introduced.
Additionally, this commit clarifies that n_ins_since_vacuum also
excludes VACUUM FULL. Although n_ins_since_vacuum was added in v13,
we are not back-patching this change to stable branches, as it is
a documentation improvement, not a bug fix.
Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Robert Treat <rob@xzilla.net>
Reviewed-by: David G. Johnston <david.g.johnston@gmail.com>
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Discussion: https://postgr.es/m/2ac375d1-591b-4f1b-a2af-f24335567866@oss.nttdata.com
Backpatch-through: 18
The grammar was a little shaky and confusing here, so word-smith it
a bit. Also, adjust the comments in pg_ident.conf.sample to use the
same terminology as the SGML docs, in particular "DATABASE-USERNAME"
not "PG-USERNAME".
Back-patch appropriate subsets. I did not risk changing
pg_ident.conf.sample in released branches, but it still seems OK
to change it in v18.
Reported-by: Alexey Shishkin <alexey.shishkin@enterprisedb.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: David G. Johnston <david.g.johnston@gmail.com>
Discussion: https://postgr.es/m/175206279327.3157504.12519088928605422253@wrigleys.postgresql.org
Backpatch-through: 13
Previously, the idle_replication_slot_timeout parameter used minutes
as its unit, based on the assumption that values would typically exceed
one minute in production environments. However, this caused unexpected
behavior: specifying a value below 30 seconds would round down to 0,
effectively disabling the timeout. This could be surprising to users.
To allow finer-grained control and avoid such confusion, this commit changes
the unit of idle_replication_slot_timeout to seconds. Larger values can
still be specified easily using standard time suffixes, for example,
'24h' for 24 hours.
Back-patch to v18 where idle_replication_slot_timeout was added.
Reported-by: Gunnar Morling <gunnar.morling@googlemail.com>
Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Reviewed-by: David G. Johnston <david.g.johnston@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CADGJaX_0+FTguWpNSpgVWYQP_7MhoO0D8=cp4XozSQgaZ40Odw@mail.gmail.com
Backpatch-through: 18
This routine has been introduced as a shortcut to be able to retrieve a
service name from an active connection, for psql. Per discussion, and
as it is only used by psql, let's remove it to not clutter the libpq API
more than necessary.
The logic in psql is replaced by lookups of PQconninfoOption for the
active connection, instead, updated each time the variables are synced
by psql, the prompt shortcut relying on the variable synced.
Reported-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/20250706161319.c1.nmisch@google.com
Backpatch-through: 18
The documentation for pg_replication_slots previously mentioned only
max_slot_wal_keep_size as a condition under which the wal_status column
could show unreserved or lost. However, since commit be87200,
replication slots can also be invalidated due to horizon or wal_level,
and since commit ac0e33136a, idle_replication_slot_timeout can also
trigger this state.
This commit updates the description of the wal_status column to
reflect that max_slot_wal_keep_size is not the only cause of the lost state.
Back-patched to v16, where the additional invalidation cases were introduced.
Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Reviewed-by: Nisha Moond <nisha.moond412@gmail.com>
Discussion: https://postgr.es/m/78b34e84-2195-4f28-a151-5d204a382fdd@oss.nttdata.com
Backpatch-through: 16
The documentation previously stated that the wal_status column is NULL
if restart_lsn is NULL in the pg_replication_slots view. This is incorrect,
and wal_status can be "lost" even when restart_lsn is NULL.
This commit removes the incorrect description.
Back-patched to all supported versions.
Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Nisha Moond <nisha.moond412@gmail.com>
Discussion: https://postgr.es/m/c9d23cdc-b5dd-455a-8ee9-f1f24d701d89@oss.nttdata.com
Backpatch-through: 13
Commit 1546e17f9d accidentally misspelled additionally as
additionaly. Backpatch to v17 to match where the original
commit was backpatched.
Author: Daniel Gustafsson <daniel@yesql.se>
Backpatch-through: 17
This commit renames the pg_recvlogical options --two-phase and
--failover to --enable-two-phase and --enable-failover, respectively.
The new names distinguish these enabling options from action options
like --start and --create-slot, while clearly indicating their purpose
to enable specific logical slot features.
The option --failover is new in PostgreSQL 18 (commit cf2655a902), so
no compatibility break there. The option --two-phase has existed
since PostgreSQL 15 (commit cda03cfed6), so for compatibility we keep
the old option name --two-phase around as deprecated.
Also note that pg_createsubscriber has acquired an --enable-two-phase
option, so this increases consistency across tools.
Co-authored-by: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/a28f66df-1354-4709-8d63-932ded4cac35@eisentraut.org
