596 Commits (0075d78947e3800c5a807f48fd901f16db91101b)

Author	SHA1	Message	Date
Amit Kapila	bf279ddd1c	Introduce a new GUC 'standby_slot_names'. ... This patch provides a way to ensure that physical standbys that are potential failover candidates have received and flushed changes before the primary server making them visible to subscribers. Doing so guarantees that the promoted standby server is not lagging behind the subscribers when a failover is necessary. The logical walsender now guarantees that all local changes are sent and flushed to the standby servers corresponding to the replication slots specified in 'standby_slot_names' before sending those changes to the subscriber. Additionally, the SQL functions pg_logical_slot_get_changes, pg_logical_slot_peek_changes and pg_replication_slot_advance are modified to ensure that they process changes for failover slots only after physical slots specified in 'standby_slot_names' have confirmed WAL receipt for those. Author: Hou Zhijie and Shveta Malik Reviewed-by: Masahiko Sawada, Peter Smith, Bertrand Drouvot, Ajin Cherian, Nisha Moond, Amit Kapila Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com	2 years ago
Alvaro Herrera	53c2a97a92	Improve performance of subsystems on top of SLRU ... More precisely, what we do here is make the SLRU cache sizes configurable with new GUCs, so that sites with high concurrency and big ranges of transactions in flight (resp. multixacts/subtransactions) can benefit from bigger caches. In order for this to work with good performance, two additional changes are made: 1. the cache is divided in "banks" (to borrow terminology from CPU caches), and algorithms such as eviction buffer search only affect one specific bank. This forestalls the problem that linear searching for a specific buffer across the whole cache takes too long: we only have to search the specific bank, whose size is small. This work is authored by Andrey Borodin. 2. Change the locking regime for the SLRU banks, so that each bank uses a separate LWLock. This allows for increased scalability. This work is authored by Dilip Kumar. (A part of this was previously committed as d172b717c6f4.) Special care is taken so that the algorithms that can potentially traverse more than one bank release one bank's lock before acquiring the next. This should happen rarely, but particularly clog.c's group commit feature needed code adjustment to cope with this. I (Álvaro) also added lots of comments to make sure the design is sound. The new GUCs match the names introduced by bcdfa5f2e2 in the pg_stat_slru view. The default values for these parameters are similar to the previous sizes of each SLRU. commit_ts, clog and subtrans accept value 0, which means to adjust by dividing shared_buffers by 512 (so 2MB for every 1GB of shared_buffers), with a cap of 8MB. (A new slru.c function SimpleLruAutotuneBuffers() was added to support this.) The cap was previously 1MB for clog, so for sites with more than 512MB of shared memory the total memory used increases, which is likely a good tradeoff. However, other SLRUs (notably multixact ones) retain smaller sizes and don't support a configured value of 0. These values based on shared_buffers may need to be revisited, but that's an easy change. There was some resistance to adding these new GUCs: it would be better to adjust to memory pressure automatically somehow, for example by stealing memory from shared_buffers (where the caches can grow and shrink naturally). However, doing that seems to be a much larger project and one which has made virtually no progress in several years, and because this is such a pain point for so many users, here we take the pragmatic approach. Author: Andrey Borodin <x4mmm@yandex-team.ru> Author: Dilip Kumar <dilipbalaut@gmail.com> Reviewed-by: Amul Sul, Gilles Darold, Anastasia Lubennikova, Ivan Lazarev, Robert Haas, Thomas Munro, Tomas Vondra, Yura Sokolov, Васильев Дмитрий (Dmitry Vasiliev). Discussion: https://postgr.es/m/2BEC2B3F-9B61-4C1D-9FB5-5FAB0F05EF86@yandex-team.ru Discussion: https://postgr.es/m/CAFiTN-vzDvNz=ExGXz6gdyjtzGixKSqs0mKHMmaQ8sOSEFZ33A@mail.gmail.com	2 years ago
Amit Kapila	93db6cbda0	Add a new slot sync worker to synchronize logical slots. ... 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	2 years ago
Alexander Korotkov	51efe38cb9	Introduce transaction_timeout ... 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>	2 years ago
Tom Lane	5c9f2f9398	Doc: improve a couple of comments in postgresql.conf.sample. ... Clarify comments associated with max_parallel_workers and related settings. Per bug #18343 from Christopher Kline. Discussion: https://postgr.es/m/18343-3a5e903d1d3692ab@postgresql.org	2 years ago
Alexander Korotkov	0452b461bc	Explore alternative orderings of group-by pathkeys during optimization. ... When evaluating a query with a multi-column GROUP BY clause, we can minimize sort operations or avoid them if we synchronize the order of GROUP BY clauses with the ORDER BY sort clause or sort order, which comes from the underlying query tree. Grouping does not imply any ordering, so we can compare the keys in arbitrary order, and a Hash Agg leverages this. But for Group Agg, we simply compared keys in the order specified in the query. This commit explores alternative ordering of the keys, trying to find a cheaper one. The ordering of group keys may interact with other parts of the query, some of which may not be known while planning the grouping. For example, there may be an explicit ORDER BY clause or some other ordering-dependent operation higher up in the query, and using the same ordering may allow using either incremental sort or even eliminating the sort entirely. The patch always keeps the ordering specified in the query, assuming the user might have additional insights. This introduces a new GUC enable_group_by_reordering so that the optimization may be disabled if needed. Discussion: https://postgr.es/m/7c79e6a5-8597-74e8-0671-1c39d124c9d6%40sigaev.ru Author: Andrei Lepikhov, Teodor Sigaev Reviewed-by: Tomas Vondra, Claudio Freire, Gavin Flower, Dmitry Dolgov Reviewed-by: Robert Haas, Pavel Borisov, David Rowley, Zhihong Yu Reviewed-by: Tom Lane, Alexander Korotkov, Richard Guo, Alena Rybakina	2 years ago
Tom Lane	3d185cfc09	Restore initdb's old behavior of always setting the lc_xxx GUCs. ... In commit 3e51b278d I (tgl) caused initdb to leave lc_messages and other lc_xxx GUCs commented-out in the installed postgresql.conf file if they were going to be set to 'C'. This was a hack for cosmetic purposes, and it was buggy because lc_messages' wired-in default is not 'C' but '' (empty string). That led to --no-locale not having the expected effect, since the postmaster would then obtain lc_messages from its startup environment. Let's just revert to the prior behavior of always de-commenting the lc_xxx entries; the argument for changing that longstanding behavior was weak in the first place. Also, fix postgresql.conf.sample's erroneous claim that the default value of lc_messages is 'C'. I suspect that was what misled me into making this mistake in the first place. Report and patch by Kyotaro Horiguchi. Back-patch to v16 where the problem was introduced. Discussion: https://postgr.es/m/20231122.162700.1995154567625541112.horikyota.ntt@gmail.com	2 years ago
Robert Haas	174c480508	Add a new WAL summarizer process. ... 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	2 years ago
Alexander Korotkov	2cdf131c46	Use larger segment file names for pg_notify ... 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	2 years ago
Bruce Momjian	75e700db45	improve alignment of postgresql.conf comments ... Discussion: https://postgr.es/m/CAHut+Ps5MdQ1b4jp9rd63zfE2X25mV58y1W+hm2v53svtGDxBQ@mail.gmail.com Author: Peter Smith Backpatch-through: master	2 years ago
Daniel Gustafsson	7750fefdb2	Add GUC for temporarily disabling event triggers ... 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	2 years ago
Thomas Munro	f691f5b80a	Remove the "snapshot too old" feature. ... Remove the old_snapshot_threshold setting and mechanism for producing the error "snapshot too old", originally added by commit 848ef42b. Unfortunately it had a number of known problems in terms of correctness and performance, mostly reported by Andres in the course of his work on snapshot scalability. We agreed to remove it, after a long period without an active plan to fix it. This is certainly a desirable feature, and someone might propose a new or improved implementation in the future. Reported-by: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/CACG%3DezYV%2BEvO135fLRdVn-ZusfVsTY6cH1OZqWtezuEYH6ciQA%40mail.gmail.com Discussion: https://postgr.es/m/20200401064008.qob7bfnnbu4w5cw4%40alap3.anarazel.de Discussion: https://postgr.es/m/CA%2BTgmoY%3Daqf0zjTD%2B3dUWYkgMiNDegDLFjo%2B6ze%3DWtpik%2B3XqA%40mail.gmail.com	2 years ago
Nathan Bossart	884eee5bfb	Remove db_user_namespace. ... This feature was intended to be a temporary measure to support per-database user names. A better one hasn't materialized in the ~21 years since it was added, and nobody claims to be using it, so let's just remove it. Reviewed-by: Michael Paquier, Magnus Hagander Discussion: https://postgr.es/m/20230630200509.GA2830328%40nathanxps13 Discussion: https://postgr.es/m/20230630215608.GD2941194%40nathanxps13	2 years ago
Peter Eisentraut	0ffbe6e591	Use lower case for icu_validation_level values ... Similar to client_min_messages etc.	3 years ago
Peter Eisentraut	dfe0169988	Punctuation improvement in postgresql.conf.sample	3 years ago
Nathan Bossart	f4001a5537	Fix remaining references to gss_accept_deleg. ... These were missed in 9c0a0e2ed9. Discussion: https://postgr.es/m/20230521031757.GA3835667%40nathanxps13	3 years ago
Jeff Davis	6de31ce446	Reduce icu_validation_level default to WARNING. ... Discussion: https://postgr.es/m/daa9f060aa2349ebc84444515efece49e7b32c5d.camel@j-davis.com	3 years ago
Michael Paquier	4d47eff99c	Document values of stats_fetch_consistency in postgresql.conf.sample ... Issue noted while looking at a patch related to that. Discussion: https://postgr.es/m/ZE9LiFc7JdNHokz/@paquier.xyz	3 years ago
Masahiko Sawada	b72f564d87	Add unit to vacuum_buffer_usage_limit value in postgresql.conf.sample. ... Also adjust the indentation of the comment to the surrounding parameters. Author: Masahiko Sawada Reviewed-by: David Rowley, Daniel Gustafsson, Melanie Plageman Discussion: https://postgr.es/m/CAD21AoCBSqmqOKVH4Q256DeCC_UE50gu1sgixcjLFZGLEbABVA@mail.gmail.com	3 years ago
Andres Freund	1118cd37eb	Remove vacuum_defer_cleanup_age ... 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	3 years ago
Stephen Frost	6633cfb216	De-Revert "Add support for Kerberos credential delegation" ... 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	3 years ago
Stephen Frost	3d03b24c35	Revert "Add support for Kerberos credential delegation" ... 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	3 years ago
Stephen Frost	3d4fa227bc	Add support for Kerberos credential delegation ... 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	3 years ago
David Rowley	1cbbee0338	Add VACUUM/ANALYZE BUFFER_USAGE_LIMIT option ... 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	3 years ago
Jeff Davis	1671f990dd	Validate ICU locales. ... 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	3 years ago
Daniel Gustafsson	b577743000	Make SCRAM iteration count configurable ... 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	3 years ago
Peter Geoghegan	6c6b497266	Revert "Add eager and lazy freezing strategies to VACUUM." ... This reverts commit 4d41799261. Broad concerns about regressions caused by eager freezing strategy have been raised. Whether or not these concerns can be worked through in any time frame is far from certain. Discussion: https://postgr.es/m/20230126004347.gepcmyenk2csxrri@awork3.anarazel.de	3 years ago
Peter Geoghegan	4d41799261	Add eager and lazy freezing strategies to VACUUM. ... Eager freezing strategy avoids large build-ups of all-visible pages. It makes VACUUM trigger page-level freezing whenever doing so will enable the page to become all-frozen in the visibility map. This is useful for tables that experience continual growth, particularly strict append-only tables such as pgbench's history table. Eager freezing significantly improves performance stability by spreading out the cost of freezing over time, rather than doing most freezing during aggressive VACUUMs. It complements the insert autovacuum mechanism added by commit b07642db. VACUUM determines its freezing strategy based on the value of the new vacuum_freeze_strategy_threshold GUC (or reloption) with logged tables. Tables that exceed the size threshold use the eager freezing strategy. Unlogged tables and temp tables always use eager freezing strategy, since the added cost is negligible there. Non-permanent relations won't incur any extra overhead in WAL written (for the obvious reason), nor in pages dirtied (since any extra freezing will only take place on pages whose PD_ALL_VISIBLE bit needed to be set either way). VACUUM uses lazy freezing strategy for logged tables that fall under the GUC size threshold. Page-level freezing triggers based on the criteria established in commit 1de58df4, which added basic page-level freezing. Eager freezing is strictly more aggressive than lazy freezing. Settings like vacuum_freeze_min_age still get applied in just the same way in every VACUUM, independent of the strategy in use. The only mechanical difference between eager and lazy freezing strategies is that only the former applies its own additional criteria to trigger freezing pages. Note that even lazy freezing strategy will trigger freezing whenever a page happens to have required that an FPI be written during pruning, provided that the page will thereby become all-frozen in the visibility map afterwards (due to the FPI optimization from commit 1de58df4). The vacuum_freeze_strategy_threshold default setting is 4GB. This is a relatively low setting that prioritizes performance stability. It will be reviewed at the end of the Postgres 16 beta period. Author: Peter Geoghegan <pg@bowt.ie> Reviewed-By: Jeff Davis <pgsql@j-davis.com> Reviewed-By: Andres Freund <andres@anarazel.de> Reviewed-By: Matthias van de Meent <boekewurm+postgres@gmail.com> Discussion: https://postgr.es/m/CAH2-WzkFok_6EAHuK39GaW4FjEFQsY=3J0AAd6FXk93u-Xq3Fg@mail.gmail.com	3 years ago
Robert Haas	6e2775e4d4	Add new GUC reserved_connections. ... This provides a way to reserve connection slots for non-superusers. The slots reserved via the new GUC are available only to users who have the new predefined role pg_use_reserved_connections. superuser_reserved_connections remains as a final reserve in case reserved_connections has been exhausted. Patch by Nathan Bossart. Reviewed by Tushar Ahuja and by me. Discussion: http://postgr.es/m/20230119194601.GA4105788@nathanxps13	3 years ago
Robert Haas	e5b8a4c098	Add new GUC createrole_self_grant. ... Can be set to the empty string, or to either or both of "set" or "inherit". If set to a non-empty value, a non-superuser who creates a role (necessarily by relying up the CREATEROLE privilege) will grant that role back to themselves with the specified options. This isn't a security feature, because the grant that this feature triggers can also be performed explicitly. Instead, it's a user experience feature. A superuser would necessarily inherit the privileges of any created role and be able to access all such roles via SET ROLE; with this patch, you can configure createrole_self_grant = 'set, inherit' to provide a similar experience for a user who has CREATEROLE but not SUPERUSER. Discussion: https://postgr.es/m/CA+TgmobN59ct+Emmz6ig1Nua2Q-_o=r6DSD98KfU53kctq_kQw@mail.gmail.com	3 years ago
Amit Kapila	216a784829	Perform apply of large transactions by parallel workers. ... Currently, for large transactions, the publisher sends the data in multiple streams (changes divided into chunks depending upon logical_decoding_work_mem), and then on the subscriber-side, the apply worker writes the changes into temporary files and once it receives the commit, it reads from those files and applies the entire transaction. To improve the performance of such transactions, we can instead allow them to be applied via parallel workers. In this approach, we assign a new parallel apply worker (if available) as soon as the xact's first stream is received and the leader apply worker will send changes to this new worker via shared memory. The parallel apply worker will directly apply the change instead of writing it to temporary files. However, if the leader apply worker times out while attempting to send a message to the parallel apply worker, it will switch to "partial serialize" mode - in this mode, the leader serializes all remaining changes to a file and notifies the parallel apply workers to read and apply them at the end of the transaction. We use a non-blocking way to send the messages from the leader apply worker to the parallel apply to avoid deadlocks. We keep this parallel apply assigned till the transaction commit is received and also wait for the worker to finish at commit. This preserves commit ordering and avoid writing to and reading from files in most cases. We still need to spill if there is no worker available. This patch also extends the SUBSCRIPTION 'streaming' parameter so that the user can control whether to apply the streaming transaction in a parallel apply worker or spill the change to disk. The user can set the streaming parameter to 'on/off', or 'parallel'. The parameter value 'parallel' means the streaming will be applied via a parallel apply worker, if available. The parameter value 'on' means the streaming transaction will be spilled to disk. The default value is 'off' (same as current behaviour). In addition, the patch extends the logical replication STREAM_ABORT message so that abort_lsn and abort_time can also be sent which can be used to update the replication origin in parallel apply worker when the streaming transaction is aborted. Because this message extension is needed to support parallel streaming, parallel streaming is not supported for publications on servers < PG16. Author: Hou Zhijie, Wang wei, Amit Kapila with design inputs from Sawada Masahiko Reviewed-by: Sawada Masahiko, Peter Smith, Dilip Kumar, Shi yu, Kuroda Hayato, Shveta Mallik Discussion: https://postgr.es/m/CAA4eK1+wyN6zpaHUkCLorEWNx75MG0xhMwcFhvjqm2KURZEAGw@mail.gmail.com	3 years ago
David Rowley	3226f47282	Add enable_presorted_aggregate GUC ... 1349d279 added query planner support to allow more efficient execution of aggregate functions which have an ORDER BY or a DISTINCT clause. Prior to that commit, the planner would only request that the lower planner produce a plan with the order required for the GROUP BY clause and it would be left up to nodeAgg.c to perform the final sort of records within each group so that the aggregate transition functions were called in the correct order. Now that the planner requests the lower planner produce a plan with the GROUP BY and the ORDER BY / DISTINCT aggregates in mind, there is the possibility that the planner chooses a plan which could be less efficient than what would have been produced before 1349d279. While developing 1349d279, I had in mind that Incremental Sort would help us in cases where an index exists only on the GROUP BY column(s). Incremental Sort would just replace the implicit tuplesorts which are being performed in nodeAgg.c. However, because the planner has the flexibility to instead choose a plan which just performs a full sort on both the GROUP BY and ORDER BY / DISTINCT aggregate columns, there is potential for the planner to make a bad choice. The costing for Incremental Sort is not perfect as it assumes an even distribution of rows to sort within each sort group. Here we add an escape hatch in the form of the enable_presorted_aggregate GUC. This will allow users to get the pre-PG16 behavior in cases where they have no other means to convince the query planner to produce a plan which only sorts on the GROUP BY column(s). Discussion: https://postgr.es/m/CAApHDvr1Sm+g9hbv4REOVuvQKeDWXcKUAhmbK5K+dfun0s9CvA@mail.gmail.com	3 years ago
Thomas Munro	cd4329d939	Remove promote_trigger_file. ... Previously, an idle startup (recovery) process would wake up every 5 seconds to have a chance to poll for promote_trigger_file, even if that GUC was not configured. That promotion triggering mechanism was effectively superseded by pg_ctl promote and pg_promote() a long time ago. There probably aren't many users left and it's very easy to change to the modern mechanisms, so we agreed to remove the feature. This is part of a campaign to reduce wakeups on idle systems. Author: Simon Riggs <simon.riggs@enterprisedb.com> Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Reviewed-by: Robert Haas <robertmhaas@gmail.com> Reviewed-by: Thomas Munro <thomas.munro@gmail.com> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Reviewed-by: Ian Lawrence Barwick <barwick@gmail.com> Discussion: https://postgr.es/m/CANbhV-FsjnzVOQGBpQ589%3DnWuL1Ex0Ykn74Nh1hEjp2usZSR5g%40mail.gmail.com	3 years ago
Tom Lane	f4c7c410ee	Revert "Optimize order of GROUP BY keys". ... This reverts commit db0d67db24 and several follow-on fixes. The idea of making a cost-based choice of the order of the sorting columns is not fundamentally unsound, but it requires cost information and data statistics that we don't really have. For example, relying on procost to distinguish the relative costs of different sort comparators is pretty pointless so long as most such comparator functions are labeled with cost 1.0. Moreover, estimating the number of comparisons done by Quicksort requires more than just an estimate of the number of distinct values in the input: you also need some idea of the sizes of the larger groups, if you want an estimate that's good to better than a factor of three or so. That's data that's often unknown or not very reliable. Worse, to arrive at estimates of the number of calls made to the lower-order-column comparison functions, the code needs to make estimates of the numbers of distinct values of multiple columns, which are necessarily even less trustworthy than per-column stats. Even if all the inputs are perfectly reliable, the cost algorithm as-implemented cannot offer useful information about how to order sorting columns beyond the point at which the average group size is estimated to drop to 1. Close inspection of the code added by db0d67db2 shows that there are also multiple small bugs. These could have been fixed, but there's not much point if we don't trust the estimates to be accurate in-principle. Finally, the changes in cost_sort's behavior made for very large changes (often a factor of 2 or so) in the cost estimates for all sorting operations, not only those for multi-column GROUP BY. That naturally changes plan choices in many situations, and there's precious little evidence to show that the changes are for the better. Given the above doubts about whether the new estimates are really trustworthy, it's hard to summon much confidence that these changes are better on the average. Since we're hard up against the release deadline for v15, let's revert these changes for now. We can always try again later. Note: in v15, I left T_PathKeyInfo in place in nodes.h even though it's unreferenced. Removing it would be an ABI break, and it seems a bit late in the release cycle for that. Discussion: https://postgr.es/m/TYAPR01MB586665EB5FB2C3807E893941F5579@TYAPR01MB5866.jpnprd01.prod.outlook.com	3 years ago
Tom Lane	31dcfae83c	Use the terminology "WAL file" not "log file" more consistently. ... Referring to the WAL as just "log" invites confusion with the postmaster log, so avoid doing that in docs and error messages. Also shorten "WAL segment file" to just "WAL file" in various places. Bharath Rupireddy, reviewed by Nathan Bossart and Kyotaro Horiguchi Discussion: https://postgr.es/m/CALj2ACUeXa8tDPaiTLexBDMZ7hgvaN+RTb957-cn5qwv9zf-MQ@mail.gmail.com	3 years ago
Michael Paquier	0b039e3a84	Fix some inconsistencies with GUC categories ... This commit addresses a few things around GUCs: - The TCP-related parameters (the four tcp_keepalives_* and client_connection_check_interval are listed in postgresql.conf.sample in a subsection called "TCP settings" of "CONNECTIONS AND AUTHENTICATION", but they did not have their own group name in guc.c. - enable_group_by_reordering, stats_fetch_consistency and recovery_prefetch had an inconsistent description, missing a dot at the end. - In postgresql.conf.sample, "Process title" should not have a section of its own, but it should be a subsection of "REPORTING AND LOGGING". This impacts the contents of pg_settings, which could be seen as a compatibility break, so no backpatch is done. This is similar to the cleanup done in a55a984. Author: Shinya Kato Discussion: https://postgr.es/m/5e0c9c608624eafbba910c344282cb14@oss.nttdata.com	3 years ago
Thomas Munro	94ebf8117c	Default to dynamic_shared_memory_type=sysv on Solaris. ... POSIX shm_open() can sleep for a long time and fail spuriously because of contention on an internal lock file on Solaris (and presumably illumos). Commit 389869af fixed the main problem with this, namely that we could crash, but it's now clear that "posix" is not a good default. Therefore, choose "sysv" at initdb time on Solaris and illumos. Other choices are still available by editing the postgresql.conf file. Back-patch only to 15, because contention is much less likely further back, and it doesn't seem like a good idea to change this in released branches. This should clear up the failures on build farm animal margay. Discussion: https://postgr.es/m/CA%2BhUKGKqKrCV5xKWfh9rnm%3Do%3DDwZLTLtnsj_XpUi9g5%3DV%2B9oyg%40mail.gmail.com	4 years ago
Andres Freund	98f897339b	Fix stats_fetch_consistency default value indicated in postgresql.conf.sample. ... Mistake in 5891c7a8ed, likely made when switching the default value from none to fetch during development. Reported-By: Nathan Bossart <nathandbossart@gmail.com> Author: Nathan Bossart <nathandbossart@gmail.com> Discussion: https://postgr.es/m/20220524220147.GA1298892@nathanxps13	4 years ago
Peter Eisentraut	9700b250c5	Formatting and punctuation improvements in sample configuration files	4 years ago
Thomas Munro	5dc0418fab	Prefetch data referenced by the WAL, take II. ... Introduce a new GUC recovery_prefetch. When enabled, look ahead in the WAL and try to initiate asynchronous reading of referenced data blocks that are not yet cached in our buffer pool. For now, this is done with posix_fadvise(), which has several caveats. Since not all OSes have that system call, "try" is provided so that it can be enabled where available. Better mechanisms for asynchronous I/O are possible in later work. Set to "try" for now for test coverage. Default setting to be finalized before release. The GUC wal_decode_buffer_size limits the distance we can look ahead in bytes of decoded data. The existing GUC maintenance_io_concurrency is used to limit the number of concurrent I/Os allowed, based on pessimistic heuristics used to infer that I/Os have begun and completed. We'll also not look more than maintenance_io_concurrency * 4 block references ahead. Reviewed-by: Julien Rouhaud <rjuju123@gmail.com> Reviewed-by: Tomas Vondra <tomas.vondra@2ndquadrant.com> Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com> (earlier version) Reviewed-by: Andres Freund <andres@anarazel.de> (earlier version) Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> (earlier version) Tested-by: Tomas Vondra <tomas.vondra@2ndquadrant.com> (earlier version) Tested-by: Jakub Wartak <Jakub.Wartak@tomtom.com> (earlier version) Tested-by: Dmitry Dolgov <9erthalion6@gmail.com> (earlier version) Tested-by: Sait Talha Nisanci <Sait.Nisanci@microsoft.com> (earlier version) Discussion: https://postgr.es/m/CA%2BhUKGJ4VJN8ttxScUFM8dOKX0BrBiboo5uz1cq%3DAovOddfHpA%40mail.gmail.com	4 years ago
Andres Freund	1db4e5a4ee	pgstat: rename STATS_COLLECTOR GUC group to STATS_CUMULATIVE. ... Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Author: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de	4 years ago
Andres Freund	6f0cf87872	pgstat: remove stats_temp_directory. ... With stats now being stored in shared memory, the GUC isn't needed anymore. However, the pg_stat_tmp directory and PG_STAT_TMP_DIR define are kept, as pg_stat_statements (and some out-of-core extensions) store data in it. Docs will be updated in a subsequent commit, together with the other pending docs updates due to shared memory stats. Author: Andres Freund <andres@anarazel.de> Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://postgr.es/m/20220330233550.eiwsbearu6xhuqwe@alap3.anarazel.de Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de	4 years ago
Andres Freund	5891c7a8ed	pgstat: store statistics in shared memory. ... Previously the statistics collector received statistics updates via UDP and shared statistics data by writing them out to temporary files regularly. These files can reach tens of megabytes and are written out up to twice a second. This has repeatedly prevented us from adding additional useful statistics. Now statistics are stored in shared memory. Statistics for variable-numbered objects are stored in a dshash hashtable (backed by dynamic shared memory). Fixed-numbered stats are stored in plain shared memory. The header for pgstat.c contains an overview of the architecture. The stats collector is not needed anymore, remove it. By utilizing the transactional statistics drop infrastructure introduced in a prior commit statistics entries cannot "leak" anymore. Previously leaked statistics were dropped by pgstat_vacuum_stat(), called from [auto-]vacuum. On systems with many small relations pgstat_vacuum_stat() could be quite expensive. Now that replicas drop statistics entries for dropped objects, it is not necessary anymore to reset stats when starting from a cleanly shut down replica. Subsequent commits will perform some further code cleanup, adapt docs and add tests. Bumps PGSTAT_FILE_FORMAT_ID. Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Author: Andres Freund <andres@anarazel.de> Author: Melanie Plageman <melanieplageman@gmail.com> Reviewed-By: Andres Freund <andres@anarazel.de> Reviewed-By: Thomas Munro <thomas.munro@gmail.com> Reviewed-By: Justin Pryzby <pryzby@telsasoft.com> Reviewed-By: "David G. Johnston" <david.g.johnston@gmail.com> Reviewed-By: Tomas Vondra <tomas.vondra@2ndquadrant.com> (in a much earlier version) Reviewed-By: Arthur Zakirov <a.zakirov@postgrespro.ru> (in a much earlier version) Reviewed-By: Antonin Houska <ah@cybertec.at> (in a much earlier version) Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de Discussion: https://postgr.es/m/20220308205351.2xcn6k4x5yivcxyd@alap3.anarazel.de Discussion: https://postgr.es/m/20210319235115.y3wz7hpnnrshdyv6@alap3.anarazel.de	4 years ago
Tomas Vondra	db0d67db24	Optimize order of GROUP BY keys ... When evaluating a query with a multi-column GROUP BY clause using sort, the cost may be heavily dependent on the order in which the keys are compared when building the groups. Grouping does not imply any ordering, so we're allowed to compare the keys in arbitrary order, and a Hash Agg leverages this. But for Group Agg, we simply compared keys in the order as specified in the query. This commit explores alternative ordering of the keys, trying to find a cheaper one. In principle, we might generate grouping paths for all permutations of the keys, and leave the rest to the optimizer. But that might get very expensive, so we try to pick only a couple interesting orderings based on both local and global information. When planning the grouping path, we explore statistics (number of distinct values, cost of the comparison function) for the keys and reorder them to minimize comparison costs. Intuitively, it may be better to perform more expensive comparisons (for complex data types etc.) last, because maybe the cheaper comparisons will be enough. Similarly, the higher the cardinality of a key, the lower the probability we’ll need to compare more keys. The patch generates and costs various orderings, picking the cheapest ones. The ordering of group keys may interact with other parts of the query, some of which may not be known while planning the grouping. E.g. there may be an explicit ORDER BY clause, or some other ordering-dependent operation, higher up in the query, and using the same ordering may allow using either incremental sort or even eliminate the sort entirely. The patch generates orderings and picks those minimizing the comparison cost (for various pathkeys), and then adds orderings that might be useful for operations higher up in the plan (ORDER BY, etc.). Finally, it always keeps the ordering specified in the query, on the assumption the user might have additional insights. This introduces a new GUC enable_group_by_reordering, so that the optimization may be disabled if needed. The original patch was proposed by Teodor Sigaev, and later improved and reworked by Dmitry Dolgov. Reviews by a number of people, including me, Andrey Lepikhov, Claudio Freire, Ibrar Ahmed and Zhihong Yu. Author: Dmitry Dolgov, Teodor Sigaev, Tomas Vondra Reviewed-by: Tomas Vondra, Andrey Lepikhov, Claudio Freire, Ibrar Ahmed, Zhihong Yu Discussion: https://postgr.es/m/7c79e6a5-8597-74e8-0671-1c39d124c9d6%40sigaev.ru Discussion: https://postgr.es/m/CA%2Bq6zcW_4o2NC0zutLkOJPsFt80megSpX_dVRo6GK9PC-Jx_Ag%40mail.gmail.com	4 years ago
Tom Lane	0bd7af082a	Invent recursive_worktable_factor GUC to replace hard-wired constant. ... Up to now, the planner estimated the size of a recursive query's worktable as 10 times the size of the non-recursive term. It's hard to see how to do significantly better than that automatically, but we can give users control over the multiplier to allow tuning for specific use-cases. The default behavior remains the same. Simon Riggs Discussion: https://postgr.es/m/CANbhV-EuaLm4H3g0+BSTYHEGxJj3Kht0R+rJ8vT57Dejnh=_nA@mail.gmail.com	4 years ago
Michael Paquier	e9537321a7	Add support for zstd with compression of full-page writes in WAL ... wal_compression gains a new value, "zstd", to allow the compression of full-page images using the compression method of the same name. Compression is done using the default level recommended by the library, as of ZSTD_CLEVEL_DEFAULT = 3. Some benchmarking has shown that it could make sense to use a level lower for the FPI compression, like 1 or 2, as the compression rate did not change much with a bit less CPU consumed, but any tests done would only cover few scenarios so it is hard to come to a clear conclusion. Anyway, there is no reason to not use the default level instead, which is the level recommended by the library so it should be fine for most cases. zstd outclasses easily pglz, and is better than LZ4 where one wants to have more compression at the cost of extra CPU but both are good enough in their own scenarios, so the choice between one or the other of these comes to a study of the workload patterns and the schema involved, mainly. This commit relies heavily on 4035cd5, that reshaped the code creating and restoring full-page writes to be aware of the compression type, making this integration straight-forward. This patch borrows some early work from Andrey Borodin, though the patch got a complete rewrite. Author: Justin Pryzby Discussion: https://postgr.es/m/20220222231948.GJ9008@telsasoft.com	4 years ago
Peter Geoghegan	8f388f6f55	Increase hash_mem_multiplier default to 2.0. ... Double the default setting for hash_mem_multiplier, from 1.0 to 2.0. This setting makes hash-based executor nodes use twice the usual work_mem limit. The PostgreSQL 15 release notes should have a compatibility note about this change. Author: Peter Geoghegan <pg@bowt.ie> Discussion: https://postgr.es/m/CAH2-Wzndc_ROk6CY-bC6p9O53q974Y0Ey4WX8jcPbuTZYM4Q3A@mail.gmail.com	4 years ago
Robert Haas	5ef1eefd76	Allow archiving via loadable modules. ... Running a shell command for each file to be archived has a lot of overhead and may not offer as much error checking as you want, or the exact semantics that you want. So, offer the option to call a loadable module for each file to be archived, rather than running a shell command. Also, add a 'basic_archive' contrib module as an example implementation that archives to a local directory. Nathan Bossart, with a little bit of kibitzing by me. Discussion: http://postgr.es/m/20220202224433.GA1036711@nathanxps13	4 years ago
Michael Paquier	dc686681e0	Introduce log_destination=jsonlog ... "jsonlog" is a new value that can be added to log_destination to provide logs in the JSON format, with its output written to a file, making it the third type of destination of this kind, after "stderr" and "csvlog". The format is convenient to feed logs to other applications. There is also a plugin external to core that provided this feature using the hook in elog.c, but this had to overwrite the output of "stderr" to work, so being able to do both at the same time was not possible. The files generated by this log format are suffixed with ".json", and use the same rotation policies as the other two formats depending on the backend configuration. This takes advantage of the refactoring work done previously in ac7c807, bed6ed3, 8b76f89 and 2d77d83 for the backend parts, and 72b76f7 for the TAP tests, making the addition of any new file-based format rather straight-forward. The documentation is updated to list all the keys and the values that can exist in this new format. pg_current_logfile() also required a refresh for the new option. Author: Sehrope Sarkuni, Michael Paquier Reviewed-by: Nathan Bossart, Justin Pryzby Discussion: https://postgr.es/m/CAH7T-aqswBM6JWe4pDehi1uOiufqe06DJWaU5=X7dDLyqUExHg@mail.gmail.com	4 years ago
Robert Haas	64da07c41a	Default to log_checkpoints=on, log_autovacuum_min_duration=10m ... The idea here is that when a performance problem is known to have occurred at a certain point in time, it's a good thing if there is some information available from the logs to help figure out what might have happened around that time. This change attracted an above-average amount of dissent, because it means that a server with default settings will produce some amount of log output even if nothing has gone wrong. However, by my count, the mailing list discussion had about twice as many people in favor of the change as opposed. The reasons for believing that the extra log output is not an issue in practice are: (1) the rate at which messages can be generated by this setting is bounded to one every few minutes on a properly-configured system and (2) production systems tend to have a lot more junk in the log from that due to failed connection attempts, ERROR messages generated by application activity, and the like. Bharath Rupireddy, reviewed by Fujii Masao and by me. Many other people commented on the thread, but as far as I can see that was discussion of the merits of the change rather than review of the patch. Discussion: https://postgr.es/m/CALj2ACX-rW_OeDcp4gqrFUAkf1f50Fnh138dmkd0JkvCNQRKGA@mail.gmail.com	4 years ago