By enabling slot synchronization, all the failover logical replication
slots on the primary (assuming configurations are appropriate) are
automatically created on the physical standbys and are synced
periodically. The slot sync worker on the standby server pings the primary
server at regular intervals to get the necessary failover logical slots
information and create/update the slots locally. The slots that no longer
require synchronization are automatically dropped by the worker.
The nap time of the worker is tuned according to the activity on the
primary. The slot sync worker waits for some time before the next
synchronization, with the duration varying based on whether any slots were
updated during the last cycle.
A new parameter sync_replication_slots enables or disables this new
process.
On promotion, the slot sync worker is shut down by the startup process to
drop any temporary slots acquired by the slot sync worker and to prevent
the worker from trying to fetch the failover slots.
A functionality to allow logical walsenders to wait for the physical will
be done in a subsequent commit.
Author: Shveta Malik, Hou Zhijie based on design inputs by Masahiko Sawada and Amit Kapila
Reviewed-by: Masahiko Sawada, Bertrand Drouvot, Peter Smith, Dilip Kumar, Ajin Cherian, Nisha Moond, Kuroda Hayato, Amit Kapila
Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
This commit adds timeout that is expected to be used as a prevention
of long-running queries. Any session within the transaction will be
terminated after spanning longer than this timeout.
However, this timeout is not applied to prepared transactions.
Only transactions with user connections are affected.
Discussion: https://postgr.es/m/CAAhFRxiQsRs2Eq5kCo9nXE3HTugsAAJdSQSmxncivebAxdmBjQ%40mail.gmail.com
Author: Andrey Borodin <amborodin@acm.org>
Author: Japin Li <japinli@hotmail.com>
Author: Junwang Zhao <zhjwpku@gmail.com>
Reviewed-by: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Fujii Masao <masao.fujii@oss.nttdata.com>
Reviewed-by: bt23nguyent <bt23nguyent@oss.nttdata.com>
Reviewed-by: Yuhang Qiu <iamqyh@gmail.com>
This commit introduces a new SQL function pg_sync_replication_slots()
which is used to synchronize the logical replication slots from the
primary server to the physical standby so that logical replication can be
resumed after a failover or planned switchover.
A new 'synced' flag is introduced in pg_replication_slots view, indicating
whether the slot has been synchronized from the primary server. On a
standby, synced slots cannot be dropped or consumed, and any attempt to
perform logical decoding on them will result in an error.
The logical replication slots on the primary can be synchronized to the
hot standby by using the 'failover' parameter of
pg-create-logical-replication-slot(), or by using the 'failover' option of
CREATE SUBSCRIPTION during slot creation, and then calling
pg_sync_replication_slots() on standby. For the synchronization to work,
it is mandatory to have a physical replication slot between the primary
and the standby aka 'primary_slot_name' should be configured on the
standby, and 'hot_standby_feedback' must be enabled on the standby. It is
also necessary to specify a valid 'dbname' in the 'primary_conninfo'.
If a logical slot is invalidated on the primary, then that slot on the
standby is also invalidated.
If a logical slot on the primary is valid but is invalidated on the
standby, then that slot is dropped but will be recreated on the standby in
the next pg_sync_replication_slots() call provided the slot still exists
on the primary server. It is okay to recreate such slots as long as these
are not consumable on standby (which is the case currently). This
situation may occur due to the following reasons:
- The 'max_slot_wal_keep_size' on the standby is insufficient to retain
WAL records from the restart_lsn of the slot.
- 'primary_slot_name' is temporarily reset to null and the physical slot
is removed.
The slot synchronization status on the standby can be monitored using the
'synced' column of pg_replication_slots view.
A functionality to automatically synchronize slots by a background worker
and allow logical walsenders to wait for the physical will be done in
subsequent commits.
Author: Hou Zhijie, Shveta Malik, Ajin Cherian based on an earlier version by Peter Eisentraut
Reviewed-by: Masahiko Sawada, Bertrand Drouvot, Peter Smith, Dilip Kumar, Nisha Moond, Kuroda Hayato, Amit Kapila
Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
The documentation for this parameter lists its type as boolean, but
it is actually an integer. Furthermore, there is no mention of how
the value is interpreted when specified without units. This commit
fixes these oversights in commit 174c480508.
Co-authored-by: Hubert Depesz Lubaczewski
Discussion: https://postgr.es/m/ZZwkujFihO2uqKwp%40depesz.com
When enabled (default off), this logs a backtrace anytime elog() or an
equivalent ereport() for internal errors is called.
This is not well covered by the existing backtrace_functions, because
there are many equally-worded low-level errors in many functions. And
if you find out where the error is, then you need to manually rewrite
the elog() to ereport() to attach the errbacktrace(), which is
annoying. Having a backtrace automatically on every elog() call could
be very helpful during development for various kinds of common errors
from palloc, syscache, node support, etc.
Discussion: https://www.postgresql.org/message-id/flat/ba76c6bc-f03f-4285-bf16-47759cfcab9e@eisentraut.org
To take an incremental backup, you use the new replication command
UPLOAD_MANIFEST to upload the manifest for the prior backup. This
prior backup could either be a full backup or another incremental
backup. You then use BASE_BACKUP with the INCREMENTAL option to take
the backup. pg_basebackup now has an --incremental=PATH_TO_MANIFEST
option to trigger this behavior.
An incremental backup is like a regular full backup except that
some relation files are replaced with files with names like
INCREMENTAL.${ORIGINAL_NAME}, and the backup_label file contains
additional lines identifying it as an incremental backup. The new
pg_combinebackup tool can be used to reconstruct a data directory
from a full backup and a series of incremental backups.
Patch by me. Reviewed by Matthias van de Meent, Dilip Kumar, Jakub
Wartak, Peter Eisentraut, and Álvaro Herrera. Thanks especially to
Jakub for incredibly helpful and extensive testing.
Discussion: http://postgr.es/m/CA+TgmoYOYZfMCyOXFyC-P+-mdrZqm5pP2N7S-r0z3_402h9rsA@mail.gmail.com
When active, this process writes WAL summary files to
$PGDATA/pg_wal/summaries. Each summary file contains information for a
certain range of LSNs on a certain TLI. For each relation, it stores a
"limit block" which is 0 if a relation is created or destroyed within
a certain range of WAL records, or otherwise the shortest length to
which the relation was truncated during that range of WAL records, or
otherwise InvalidBlockNumber. In addition, it stores a list of blocks
which have been modified during that range of WAL records, but
excluding blocks which were removed by truncation after they were
modified and never subsequently modified again.
In other words, it tells us which blocks need to copied in case of an
incremental backup covering that range of WAL records. But this
doesn't yet add the capability to actually perform an incremental
backup; the next patch will do that.
A new parameter summarize_wal enables or disables this new background
process. The background process also automatically deletes summary
files that are older than wal_summarize_keep_time, if that parameter
has a non-zero value and the summarizer is configured to run.
Patch by me, with some design help from Dilip Kumar and Andres Freund.
Reviewed by Matthias van de Meent, Dilip Kumar, Jakub Wartak, Peter
Eisentraut, and Álvaro Herrera.
Discussion: http://postgr.es/m/CA+TgmoYOYZfMCyOXFyC-P+-mdrZqm5pP2N7S-r0z3_402h9rsA@mail.gmail.com
This GUC was intended as a debugging help in the 9.0 area when hot
standby and streaming replication were being developped, able to offer
more information at LOG level rather than DEBUGn. There are more tools
available these days that are able to offer rather equivalent
information, like pg_waldump introduced in 9.3. It is not obvious how
this facility is useful these days, so let's remove it.
Author: Bharath Rupireddy
Discussion: https://postgr.es/m/ZXEXEAUVFrvpquSd@paquier.xyz
This avoids the wraparound in async.c and removes the corresponding code
complexity. The maximum amount of allocated SLRU pages for NOTIFY / LISTEN
queue is now determined by the max_notify_queue_pages GUC. The default
value is 1048576. It allows to consume up to 8 GB of disk space which is
exactly the limit we had previously.
Author: Maxim Orlov, Aleksander Alekseev, Alexander Korotkov, Teodor Sigaev
Author: Nikita Glukhov, Pavel Borisov, Yura Sokolov
Reviewed-by: Jacob Champion, Heikki Linnakangas, Alexander Korotkov
Reviewed-by: Japin Li, Pavel Borisov, Tom Lane, Peter Eisentraut, Andres Freund
Reviewed-by: Andrey Borodin, Dilip Kumar, Aleksander Alekseev
Discussion: https://postgr.es/m/CACG%3DezZe1NQSCnfHOr78AtAZxJZeCvxrts0ygrxYwe%3DpyyjVWA%40mail.gmail.com
Discussion: https://postgr.es/m/CAJ7c6TPDOYBYrnCAeyndkBktO0WG2xSdYduTF0nxq%2BvfkmTF5Q%40mail.gmail.com
This commit log messages (at LOG level when log_replication_commands is
set, otherwise at DEBUG1 level) when walsenders acquire and release
replication slots. These messages help to know the lifetime of a
replication slot - one can know how long a streaming standby, logical
subscriber, or replication slot consumer is down. These messages will be
useful on production servers to debug and analyze inactive replication
slots.
Note that these messages are emitted only for walsenders but not for
backends. This is because walsenders are the ones that typically hold
replication slots for longer durations, unlike backends which hold them
for executing replication related functions.
Author: Bharath Rupireddy
Reviewed-by: Peter Smith, Amit Kapila, Alvaro Herrera
Discussion: http://postgr.es/m/CALj2ACX17G7F-jeLt+7KhJ6YxVeRwR8Zk0rDh4VnT546o0UpTQ@mail.gmail.com
Commit 536f410111 added links in the ALTER SUBSCRIPTION command page. The
link names used were slightly different from what other logical
replication commands like CREATE SUBSCRIPTION/PUBLICATION have but were
consistent with other docs. This patch changes the link names for all the
parameters to have 'params' word in the CREATE SUBSCRIPTION/PUBLICATION
pages.
Author: Peter Smith
Reviewed-by: Amit Kapila
Discussion: http://postgr.es/m/CAHut%2BPu2S4RdzYKR7H5_E7QYWyq5hB0hL4EFrYbP91Qso62jeg%40mail.gmail.com
The Self Join Elimination (SJE) feature removes an inner join of a plain table
to itself in the query tree if is proved that the join can be replaced with
a scan without impacting the query result. Self join and inner relation are
replaced with the outer in query, equivalence classes, and planner info
structures. Also, inner restrictlist moves to the outer one with removing
duplicated clauses. Thus, this optimization reduces the length of the range
table list (this especially makes sense for partitioned relations), reduces
the number of restriction clauses === selectivity estimations, and potentially
can improve total planner prediction for the query.
The SJE proof is based on innerrel_is_unique machinery.
We can remove a self-join when for each outer row:
1. At most one inner row matches the join clause.
2. Each matched inner row must be (physically) the same row as the outer one.
In this patch we use the next approach to identify a self-join:
1. Collect all merge-joinable join quals which look like a.x = b.x
2. Add to the list above the baseretrictinfo of the inner table.
3. Check innerrel_is_unique() for the qual list. If it returns false, skip
this pair of joining tables.
4. Check uniqueness, proved by the baserestrictinfo clauses. To prove
the possibility of self-join elimination inner and outer clauses must have
an exact match.
The relation replacement procedure is not trivial and it is partly combined
with the one, used to remove useless left joins. Tests, covering this feature,
were added to join.sql. Some regression tests changed due to self-join removal
logic.
Discussion: https://postgr.es/m/flat/64486b0b-0404-e39e-322d-0801154901f3%40postgrespro.ru
Author: Andrey Lepikhov, Alexander Kuzmenkov
Reviewed-by: Tom Lane, Robert Haas, Andres Freund, Simon Riggs, Jonathan S. Katz
Reviewed-by: David Rowley, Thomas Munro, Konstantin Knizhnik, Heikki Linnakangas
Reviewed-by: Hywel Carver, Laurenz Albe, Ronan Dunklau, vignesh C, Zhihong Yu
Reviewed-by: Greg Stark, Jaime Casanova, Michał Kłeczek, Alena Rybakina
Reviewed-by: Alexander Korotkov
In order to troubleshoot misbehaving or buggy event triggers, the
documented advice is to enter single-user mode. In an attempt to
reduce the number of situations where single-user mode is required
(or even recommended) for non-extraordinary maintenance, this GUC
allows to temporarily suspend event triggers.
This was originally extracted from a larger patchset which aimed
at supporting event triggers on login events.
Reviewed-by: Ted Yu <yuzhihong@gmail.com>
Reviewed-by: Mikhail Gribkov <youzhick@gmail.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/9140106E-F9BF-4D85-8FC8-F2D3C094A6D9@yesql.se
Discussion: https://postgr.es/m/0d46d29f-4558-3af9-9c85-7774e14a7709@postgrespro.ru
This commit allows specifying a --sync-method in several frontend
utilities that must synchronize many files to disk (initdb,
pg_basebackup, pg_checksums, pg_dump, pg_rewind, and pg_upgrade).
On Linux, users can specify "syncfs" to synchronize the relevant
file systems instead of calling fsync() for every single file. In
many cases, using syncfs() is much faster.
As with recovery_init_sync_method, this new option comes with some
caveats. The descriptions of these caveats have been moved to a
new appendix section in the documentation.
Co-authored-by: Justin Pryzby
Reviewed-by: Michael Paquier, Thomas Munro, Robert Haas, Justin Pryzby
Discussion: https://postgr.es/m/20210930004340.GM831%40telsasoft.com
The logical_replication_mode GUC is intended for testing and debugging
purposes, but its current name may be misleading and encourage users to make
unnecessary changes.
To avoid confusion, renaming the GUC to a less misleading name
debug_logical_replication_streaming that casual users are less likely to mistakenly
assume needs to be modified in a regular logical replication setup.
Author: Hou Zhijie <houzj.fnst@cn.fujitsu.com>
Reviewed-by: Peter Smith <smithpb2250@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/d672d774-c44b-6fec-f993-793e744f169a%40eisentraut.org
This is useful to show the allocation state of huge pages when setting
up a server with "huge_pages = try", where allocating huge pages would
be attempted but the server would continue its startup sequence even if
the allocation fails. The effective status of huge pages is not easily
visible without OS-level tools (or for instance, a lookup at
/proc/N/smaps), and the environments where Postgres runs may not
authorize that. Like the other GUCs related to huge pages, this works
for Linux and Windows.
This GUC can report as values:
- "on", if huge pages were allocated.
- "off", if huge pages were not allocated.
- "unknown", a special state that could only be seen when using for
example postgres -C because it is only possible to know if the shared
memory allocation worked after we can check for the GUC values, even if
checking a runtime-computed GUC. This value should never be seen when
querying for the GUC on a running server. An assertion is added to
check that.
The discussion has also turned around having a new function to grab this
status, but this would have required more tricks for -DEXEC_BACKEND,
something that GUCs already handle.
Noriyoshi Shinoda has initiated the thread that has led to the result of
this commit.
Author: Justin Pryzby
Reviewed-by: Nathan Bossart, Kyotaro Horiguchi, Michael Paquier
Discussion: https://postgr.es/m/TU4PR8401MB1152EBB0D271F827E2E37A01EECC9@TU4PR8401MB1152.NAMPRD84.PROD.OUTLOOK.COM
The GUC settings lc_collate and lc_ctype are from a time when those
locale settings were cluster-global. When those locale settings were
made per-database (PG 8.4), the settings were kept as read-only. As
of PG 15, you can use ICU as the per-database locale provider, so
examining these settings is already less meaningful and possibly
confusing, since you need to look into pg_database to find out what is
really happening, and they would likely become fully obsolete in the
future anyway.
Reviewed-by: Jeff Davis <pgsql@j-davis.com>
Discussion: https://www.postgresql.org/message-id/696054d1-bc88-b6ab-129a-18b8bce6a6f0@enterprisedb.com
Give the new GUC introduced by d4e71df6 a name that is clearly not
intended for mainstream use quite yet.
Future proposals would drop the prefix only after adding infrastructure
to make it efficient. Having the switch in the tree sooner is good
because it might lead to new discoveries about the hazards awaiting us
on a wide range of systems, but that name was too enticing and could
lead to cross-version confusion in future, per complaints from Noah and
Justin.
Suggested-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> (the idea, not the patch)
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (ditto)
Discussion: https://postgr.es/m/20230430041106.GA2268796%40rfd.leadboat.com
An update of the GUC stats_fetch_consistency in a transaction would be
able to trigger an assertion when doing cache->snapshot. In this case,
when retrieving a pgstat entry after the switch, a new snapshot would be
rebuilt, confusing pgstat_build_snapshot() because a snapshot is already
cached with an unexpected mode ("cache").
In order to fix this problem, this commit adds a flag to force a
snapshot clear each time this GUC is changed. Some tests are added to
check, while on it.
Some optimizations in avoiding the snapshot clear should be possible
depending on what is cached and the current GUC value, I guess, but this
solution is simple, and ensures that the state of the cache is updated
each time a new pgstat entry is fetched, hence being consistent with the
level wanted by the client that has set the GUC.
Note that cache->none and snapshot->none would not cause issues, as
fetching a pgstat entry would be retrieved from shared memory on the
second attempt, however a snapshot would still be cached. Similarly,
none->snapshot and none->cache would build a new snapshot on the second
fetch attempt. Finally, snapshot->cache would cache a new snapshot on
the second attempt.
Reported-by: Alexander Lakhin
Author: Kyotaro Horiguchi
Discussion: https://postgr.es/m/17804-2a118cd046f2d0e5@postgresql.org
backpatch-through: 15
vacuum_defer_cleanup_age was introduced before hot_standby_feedback and
replication slots existed. It is hard to use reasonably - commonly it will
either be set too low (not preventing recovery conflicts, while still causing
some bloat), or too high (causing a lot of bloat). The alternatives do not
have that issue.
That on its own might not be sufficient reason to remove
vacuum_defer_cleanup_age, but it also complicates computation of xid
horizons. See e.g. the bug fixed in be504a3e97. It also is untested.
This commit removes TransactionIdRetreatSafely(), as there are no users
anymore. There might be potential future users, hence noting that here.
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/20230317230930.nhsgk3qfk7f4axls@awork3.anarazel.de
This reverts commit 3d03b24c3 (Revert Add support for Kerberos
credential delegation) which was committed on the grounds of concern
about portability, but on further review and discussion, it's clear that
we are better off explicitly requiring MIT Kerberos as that appears to
be the only GSSAPI library currently that's under proper maintenance
and ongoing development. The API used for storing credentials was added
to MIT Kerberos over a decade ago while for the other libraries which
appear to be mainly based on Heimdal, which exists explicitly to be a
re-implementation of MIT Kerberos, the API never made it to a released
version (even though it was added to the Heimdal git repo over 5 years
ago..).
This post-feature-freeze change was approved by the RMT.
Discussion: https://postgr.es/m/ZDDO6jaESKaBgej0%40tamriel.snowman.net
This reverts commit 3d4fa227bc.
Per discussion and buildfarm, this depends on APIs that seem to not
be available on at least one platform (NetBSD). Should be certainly
possible to rework to be optional on that platform if necessary but bit
late for that at this point.
Discussion: https://postgr.es/m/3286097.1680922218@sss.pgh.pa.us
Provide a way to ask the kernel to use O_DIRECT (or local equivalent)
where available for data and WAL files, to avoid or minimize kernel
caching. This hurts performance currently and is not intended for end
users yet. Later proposed work would introduce our own I/O clustering,
read-ahead, etc to replace the facilities the kernel disables with this
option.
The only user-visible change, if the developer-only GUC is not used, is
that this commit also removes the obscure logic that would activate
O_DIRECT for the WAL when wal_sync_method=open_[data]sync and
wal_level=minimal (which also requires max_wal_senders=0). Those are
non-default and unlikely settings, and this behavior wasn't (correctly)
documented. The same effect can be achieved with io_direct=wal.
Author: Thomas Munro <thomas.munro@gmail.com>
Author: Andres Freund <andres@anarazel.de>
Author: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGK1X532hYqJ_MzFWt0n1zt8trz980D79WbjwnT-yYLZpg%40mail.gmail.com
Support GSSAPI/Kerberos credentials being delegated to the server by a
client. With this, a user authenticating to PostgreSQL using Kerberos
(GSSAPI) credentials can choose to delegate their credentials to the
PostgreSQL server (which can choose to accept them, or not), allowing
the server to then use those delegated credentials to connect to
another service, such as with postgres_fdw or dblink or theoretically
any other service which is able to be authenticated using Kerberos.
Both postgres_fdw and dblink are changed to allow non-superuser
password-less connections but only when GSSAPI credentials have been
delegated to the server by the client and GSSAPI is used to
authenticate to the remote system.
Authors: Stephen Frost, Peifeng Qiu
Reviewed-By: David Christensen
Discussion: https://postgr.es/m/CO1PR05MB8023CC2CB575E0FAAD7DF4F8A8E29@CO1PR05MB8023.namprd05.prod.outlook.com
The old wording described these as being multiplied by max_connections
plus max_prepared_transactions, which hasn't been exactly right for
some time thanks to the addition of various auxiliary processes.
Moreover, exactness here is a bit pointless given that the lock tables
can expand into the initially-unallocated "slop" space in shared
memory. Rather than trying to track exactly what the code is doing,
let's just use the term "server processes".
Likewise adjust these GUCs' description strings in guc_tables.c.
Wang Wei, reviewed by Nathan Bossart and myself
Discussion: https://postgr.es/m/OS3PR01MB6275BDD09C9B875C65FCC5AB9EA39@OS3PR01MB6275.jpnprd01.prod.outlook.com
1cbbee033 added BUFFER_USAGE_LIMIT to the VACUUM and ANALYZE commands, so
here we permit that option to be specified in vacuumdb.
In passing, adjust the documents for vacuum_buffer_usage_limit and the
BUFFER_USAGE_LIMIT VACUUM option to mention "kB" rather than "KB". Do the
same for the ERROR message in ExecVacuum() and
check_vacuum_buffer_usage_limit(). Without that we might tell a user that
the valid minimum value is 128 KB only to reject that because we accept
only "kB" and not "KB".
Also, add a small reminder comment in vacuum.h to try to trigger the
memory of anyone adding new fields to VacuumParams that they might want to
consider if vacuumdb needs to grow a new option too.
Author: Melanie Plageman
Reviewed-by: Justin Pryzby
Reviewed-by: David Rowley
Discussion: https://postgr.es/m/ZAzTg3iEnubscvbf@telsasoft.com
Add new options to the VACUUM and ANALYZE commands called
BUFFER_USAGE_LIMIT to allow users more control over how large to make the
buffer access strategy that is used to limit the usage of buffers in
shared buffers. Larger rings can allow VACUUM to run more quickly but
have the drawback of VACUUM possibly evicting more buffers from shared
buffers that might be useful for other queries running on the database.
Here we also add a new GUC named vacuum_buffer_usage_limit which controls
how large to make the access strategy when it's not specified in the
VACUUM/ANALYZE command. This defaults to 256KB, which is the same size as
the access strategy was prior to this change. This setting also
controls how large to make the buffer access strategy for autovacuum.
Per idea by Andres Freund.
Author: Melanie Plageman
Reviewed-by: David Rowley
Reviewed-by: Andres Freund
Reviewed-by: Justin Pryzby
Reviewed-by: Bharath Rupireddy
Discussion: https://postgr.es/m/20230111182720.ejifsclfwymw2reb@awork3.anarazel.de
Traditionally, vacuum always makes use of a buffer access strategy 32
buffers in size. This means that running vacuums tend not to cause too
many shared buffers to become dirty, however, this can cause vacuums to
run much more slowly than they otherwise could as WAL flushes will occur
more frequently due to having to flush WAL out to the LSN of the dirty
page before that page can be written to disk.
When we are performing failsafe VACUUMs (as added in 1e55e7d17), we really
want to make the vacuum work go as quickly as possible, so here we disable
the buffer access strategy when entering failsafe mode while vacuuming a
relation.
Per idea and analyis from Andres Freund.
In passing, also include some changes I had intended for 32fbe0239.
Author: Melanie Plageman
Reviewed-by: Justin Pryzby, David Rowley
Discussion: https://postgr.es/m/20230111182720.ejifsclfwymw2reb%40awork3.anarazel.de
Commit ecb696527c added an XML ID attribute to one varlistentry in
create_subscription.sgml. Following 78ee60ed84, this commit adds XML ID
attributes to all varlistentries in create_subscription.sgml.
Additionally, links are added to refer to the subscription options,
enhancing the readability of documents.
Author: Kuroda Hayato
Reviewed-by: Peter Smith, Amit Kapila
Discussion: https://postgr.es/m/TYAPR01MB58667AE04D291924671E2051F5879@TYAPR01MB5866.jpnprd01.prod.outlook.com
For ICU collations, ensure that the locale's language exists in ICU,
and that the locale can be opened.
Basic validation helps avoid minor mistakes and misspellings, which
often fall back to the root locale instead of the intended
locale. It's even more important to avoid such mistakes in ICU
versions 54 and earlier, where the same (misspelled) locale string
could fall back to different locales depending on the environment.
Discussion: https://postgr.es/m/11b1eeb7e7667fdd4178497aeb796c48d26e69b9.camel@j-davis.com
Discussion: https://postgr.es/m/df2efad0cae7c65180df8e5ebb709e5eb4f2a82b.camel@j-davis.com
Reviewed-by: Peter Eisentraut
Replace the hardcoded value with a GUC such that the iteration
count can be raised in order to increase protection against
brute-force attacks. The hardcoded value for SCRAM iteration
count was defined to be 4096, which is taken from RFC 7677, so
set the default for the GUC to 4096 to match. In RFC 7677 the
recommendation is at least 15000 iterations but 4096 is listed
as a SHOULD requirement given that it's estimated to yield a
0.5s processing time on a mobile handset of the time of RFC
writing (late 2015).
Raising the iteration count of SCRAM will make stored passwords
more resilient to brute-force attacks at a higher computational
cost during connection establishment. Lowering the count will
reduce computational overhead during connections at the tradeoff
of reducing strength against brute-force attacks.
There are however platforms where even a modest iteration count
yields a too high computational overhead, with weaker password
encryption schemes chosen as a result. In these situations,
SCRAM with a very low iteration count still gives benefits over
weaker schemes like md5, so we allow the iteration count to be
set to one at the low end.
The new GUC is intentionally generically named such that it can
be made to support future SCRAM standards should they emerge.
At that point the value can be made into key:value pairs with
an undefined key as a default which will be backwards compatible
with this.
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Jonathan S. Katz <jkatz@postgresql.org>
Discussion: https://postgr.es/m/F72E7BC7-189F-4B17-BF47-9735EB72C364@yesql.se
Alexander Korotkov