104 Commits (3d1ef3a15c3eb68dae44b94e89d04c422b26fc16)

Author	SHA1	Message	Date
Alexander Korotkov	d3d55ce571	Remove useless self-joins ... 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	2 years ago
Nathan Bossart	8d140c5822	Improve the naming in wal_sync_method code. ... * sync_method is renamed to wal_sync_method. * sync_method_options[] is renamed to wal_sync_method_options[]. * assign_xlog_sync_method() is renamed to assign_wal_sync_method(). * The names of the available synchronization methods are now prefixed with "WAL_SYNC_METHOD_" and have been moved into a WalSyncMethod enum. * PLATFORM_DEFAULT_SYNC_METHOD is renamed to PLATFORM_DEFAULT_WAL_SYNC_METHOD, and DEFAULT_SYNC_METHOD is renamed to DEFAULT_WAL_SYNC_METHOD. These more descriptive names help distinguish the code for wal_sync_method from the code for DataDirSyncMethod (e.g., the recovery_init_sync_method configuration parameter and the --sync-method option provided by several frontend utilities). This change also prevents name collisions between the aforementioned sets of code. Since this only improves the naming of internal identifiers, there should be no behavior change. Author: Maxim Orlov Discussion: https://postgr.es/m/CACG%3DezbL1gwE7_K7sr9uqaCGkWhmvRTcTEnm3%2BX1xsRNwbXULQ%40mail.gmail.com	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
Nathan Bossart	3ed1956719	Make enum for sync methods available to frontend code. ... This commit renames RecoveryInitSyncMethod to DataDirSyncMethod and moves it to common/file_utils.h. This is preparatory work for a follow-up commit that will allow specifying the synchronization method in frontend utilities such as pg_upgrade and pg_basebackup. Reviewed-by: Michael Paquier Discussion: https://postgr.es/m/ZN2ZB4afQ2JbR9TA%40paquier.xyz	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
Peter Eisentraut	63956bed7b	Rename logical_replication_mode to debug_logical_replication_streaming ... 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	2 years ago
Peter Eisentraut	36e4419d1f	Make error messages about WAL segment size more consistent ... Make the primary messages more compact and make the detail messages uniform. In initdb.c and pg_resetwal.c, use the newish option_parse_int() to simplify some of the option parsing. For the backend GUC wal_segment_size, add a GUC check hook to do the verification instead of coding it in bootstrap.c. This might be overkill, but that way the check is in the right place and it becomes more self-documenting. In passing, make pg_controldata use the logging API for warning messages. Reviewed-by: Aleksander Alekseev <aleksander@timescale.com> Discussion: https://www.postgresql.org/message-id/flat/9939aa8a-d7be-da2c-7715-0a0b5535a1f7@eisentraut.org	2 years ago
Peter Eisentraut	4f3514f201	Rename hook functions for debug_io_direct to match variable name. ... Commit 319bae9a renamed the GUC. Rename the check and assign functions to match, and alphabetize. Back-patch to 16. Author: Peter Eisentraut <peter@eisentraut.org> Discussion: https://postgr.es/m/2769341e-fa28-c2ee-3e4b-53fdcaaf2271%40eisentraut.org	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
Nathan Bossart	0fef877538	Rename session_auth_is_superuser to current_role_is_superuser. ... This variable might've been accurately named when it was added in ea886339b8, but the name hasn't been accurate since at least the introduction of SET ROLE in e5d6b91220. The corresponding documentation was fixed in eedb068c0a. This commit renames the variable accordingly. Suggested-by: Joseph Koshakow Discussion: https://postgr.es/m/CAAvxfHc-HHzONQ2oXdvhFF9ayRnidPwK%2BfVBhRzaBWYYLVQL-g%40mail.gmail.com	2 years ago
Peter Eisentraut	e53a611523	Message wording improvements	2 years ago
Michael Paquier	a14354cac0	Add GUC parameter "huge_pages_status" ... 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	2 years ago
Peter Eisentraut	7a7f60aef8	Add macro for maximum statistics target ... The number of places where 10000 was hardcoded had grown a bit beyond the comfort level. Introduce a macro MAX_STATISTICS_TARGET instead. Reviewed-by: Tomas Vondra <tomas.vondra@enterprisedb.com> Discussion: https://www.postgresql.org/message-id/flat/d6069765-5971-04d3-c10d-e4f7b2e9c459%40eisentraut.org	3 years ago
Heikki Linnakangas	548d726030	Remove a few unused global variables and declarations. ... - Commit 3eb77eba5a, which moved the pending ops queue from md.c to sync.c, introduced a duplicate, unused 'pendingOpsCxt' variable. (I'm surprised none of the compilers or static analysis tools have complained about that.) - Commit c2fe139c20 moved the 'synchronize_seqscans' variable and introduced an extern declaration in tableam.h, making the one in guc_tables.c unnecessary. - Commit 6f0cf87872 removed the 'pgstat_temp_directory' GUC, but forgot to remove the corresponding global variable. - Commit 1b4e729eaa removed the 'pg_krb_realm' GUC, and its global variable, but forgot the declaration in auth.h. Spotted all these by reading the code.	3 years ago
Peter Eisentraut	b0f6c43716	Remove read-only server settings lc_collate and lc_ctype ... 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	3 years ago
Bruce Momjian	9c0a0e2ed9	rename "gss_accept_deleg" to "gss_accept_delegation". ... This is more consistent with existing GUC spelling. Discussion: https://postgr.es/m/ZGdnEsGtNj7+fZoa@momjian.us	3 years ago
Tom Lane	0245f8db36	Pre-beta mechanical code beautification. ... Run pgindent, pgperltidy, and reformat-dat-files. This set of diffs is a bit larger than typical. We've updated to pg_bsd_indent 2.1.2, which properly indents variable declarations that have multi-line initialization expressions (the continuation lines are now indented one tab stop). We've also updated to perltidy version 20230309 and changed some of its settings, which reduces its desire to add whitespace to lines to make assignments etc. line up. Going forward, that should make for fewer random-seeming changes to existing code. Discussion: https://postgr.es/m/20230428092545.qfb3y5wcu4cm75ur@alvherre.pgsql	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
Thomas Munro	63932a6d38	Fix wal_writer_flush_after initializer value. ... Commit a73952b795 (new in 16) required default values in guc_table.c and C variable initializers to match. This one only matched when XLOG_BLCKSZ == 8kB. Fix by using the same expression in both places with a new DEFAULT_XXX macro, as done for other GUCs. Reviewed-by: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/CA+hUKGLNmLV=VrT==5MqnbARgx2ifRSFtdd8ofdfrdSLL3yv5A@mail.gmail.com	3 years ago
Thomas Munro	319bae9a8d	Rename io_direct to debug_io_direct. ... 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	3 years ago
Michael Paquier	605994651b	Fix assertion failure when updating stats_fetch_consistency in a transaction ... 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	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
Thomas Munro	d4e71df6d7	Add io_direct setting (developer-only). ... 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	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
Tom Lane	ff245a3788	Doc: improve descriptions of max_[pred_]locks_per_transaction GUCs. ... 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	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
Michael Paquier	35739b87dc	Redesign archive modules ... A new callback named startup_cb, called shortly after a module is loaded, is added. This makes possible the initialization of any additional state data required by a module. This initial state data can be saved in a ArchiveModuleState, that is now passed down to all the callbacks that can be defined in a module. With this design, it is possible to have a per-module state, aimed at opening the door to the support of more than one archive module. The initialization of the callbacks is changed so as _PG_archive_module_init() does not anymore give in input a ArchiveModuleCallbacks that a module has to fill in with callback definitions. Instead, a module now needs to return a const ArchiveModuleCallbacks. All the structure and callback definitions of archive modules are moved into their own header, named archive_module.h, from pgarch.h. Command-based archiving follows the same line, with a new set of files named shell_archive.{c,h}. There are a few more items that are under discussion to improve the design of archive modules, like the fact that basic_archive calls sigsetjmp() by itself to define its own error handling flow. These will be adjusted later, the changes done here cover already a good portion of what has been discussed. Any modules created for v15 will need to be adjusted to this new design. Author: Nathan Bossart Reviewed-by: Andres Freund Discussion: https://postgr.es/m/20230130194810.6fztfgbn32e7qarj@awork3.anarazel.de	3 years ago
David Rowley	5352ca22e0	Rename force_parallel_mode to debug_parallel_query ... force_parallel_mode is meant to be used to allow us to exercise the parallel query infrastructure to ensure that it's working as we expect. It seems some users think this GUC is for forcing the query planner into picking a parallel plan regardless of the costs. A quick look at the documentation would have made them realize that they were wrong, but the GUC is likely too conveniently named which, evidently, seems to often result in users expecting that it forces the planner into usefully parallelizing queries. Here we rename the GUC to something which casual users are less likely to mistakenly think is what they need to make their query run more quickly. For now, the old name can still be used. We'll revisit if the old name mapping can be removed once the buildfarm configs are all updated. Reviewed-by: John Naylor Discussion: https://postgr.es/m/CAApHDvrsOi92_uA7PEaHZMH-S4Xv+MGhQWA+GrP8b1kjpS1HjQ@mail.gmail.com	3 years ago
Amit Kapila	9f2213a7c5	Allow the logical_replication_mode to be used on the subscriber. ... Extend the existing developer option 'logical_replication_mode' to help test the parallel apply of large transactions on the subscriber. When set to 'buffered', the leader sends changes to parallel apply workers via a shared memory queue. When set to 'immediate', the leader serializes all changes to files and notifies the parallel apply workers to read and apply them at the end of the transaction. This helps in adding tests to cover the serialization code path in parallel streaming mode. Author: Hou Zhijie Reviewed-by: Peter Smith, Kuroda Hayato, Sawada Masahiko, Amit Kapila Discussion: https://postgr.es/m/CAA4eK1+wyN6zpaHUkCLorEWNx75MG0xhMwcFhvjqm2KURZEAGw@mail.gmail.com	3 years ago
Amit Kapila	1e8b61735c	Rename GUC logical_decoding_mode to logical_replication_mode. ... Rename the developer option 'logical_decoding_mode' to the more flexible name 'logical_replication_mode' because doing so will make it easier to extend this option in the future to help test other areas of logical replication. Currently, it is used on the publisher side to allow streaming or serializing each change in logical decoding. In the upcoming patch, we are planning to use it on the subscriber. On the subscriber, it will allow serializing the changes to file and notifies the parallel apply workers to read and apply them at the end of the transaction. We discussed exposing this parameter as a subscription option but it did not seem advisable since it is primarily used for testing/debugging and there is no other such parameter. We also discussed having separate GUCs for publisher and subscriber but for current testing/debugging requirements, one GUC is sufficient. Author: Hou Zhijie Reviewed-by: Peter Smith, Kuroda Hayato, Sawada Masahiko, Amit Kapila Discussion: https://postgr.es/m/CAD21AoAy2c=Mx=FTCs+EwUsf2kQL5MmU3N18X84k0EmCXntK4g@mail.gmail.com Discussion: https://postgr.es/m/CAA4eK1+wyN6zpaHUkCLorEWNx75MG0xhMwcFhvjqm2KURZEAGw@mail.gmail.com	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
Michael Paquier	8eba3e3f02	Move queryjumble.c code to src/backend/nodes/ ... This will ease a follow-up move that will generate automatically this code. The C file is renamed, for consistency with the node-related files whose code are generated by gen_node_support.pl: - queryjumble.c -> queryjumblefuncs.c - utils/queryjumble.h -> nodes/queryjumble.h Per a suggestion from Peter Eisentraut. Reviewed-by: Peter Eisentraut Discussion: https://postgr.es/m/Y5BHOUhX3zTH/ig6@paquier.xyz	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	fe00fec1f5	Rename ReservedBackends variable to SuperuserReservedConnections. ... This is in preparation for adding a new reserved_connections GUC, but aligning the GUC name with the variable name is also a good idea on general principle. Patch by Nathan Bossart. Reviewed by Tushar Ahuja and by me. Discussion: http://postgr.es/m/20230119194601.GA4105788@nathanxps13	3 years ago
Michael Paquier	7e8a80d1fe	Add missing assign hook for GUC checkpoint_completion_target ... This is wrong since 88e9823, that has switched the WAL sizing configuration from checkpoint_segments to min_wal_size and max_wal_size. This missed the recalculation of the internal value of the internal "CheckPointSegments", that works as a mapping of the old GUC checkpoint_segments, on reload, for example, and it controls the timing of checkpoints depending on the volume of WAL generated. Most users tend to leave checkpoint_completion_target at 0.9 to smooth the I/O workload, which is why I guess this has gone unnoticed for so long, still it can be useful to tweak and reload the value dynamically in some cases to control the timing of checkpoints. Author: Bharath Rupireddy Discussion: https://postgr.es/m/CALj2ACXgPPAm28mruojSBno+F_=9cTOOxHAywu_dfZPeBdybQw@mail.gmail.com Backpatch-through: 11	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
Bruce Momjian	c8e1ba736b	Update copyright for 2023 ... Backpatch-through: 11	3 years ago
Amit Kapila	5de94a041e	Add 'logical_decoding_mode' GUC. ... This enables streaming or serializing changes immediately in logical decoding. This parameter is intended to be used to test logical decoding and replication of large transactions for which otherwise we need to generate the changes till logical_decoding_work_mem is reached. This helps in reducing the timing of existing tests related to logical replication of in-progress transactions and will help in writing tests for for the upcoming feature for parallelly applying large in-progress transactions. Author: Shi yu Reviewed-by: Sawada Masahiko, Shveta Mallik, Amit Kapila, Dilip Kumar, Kuroda Hayato, Kyotaro Horiguchi Discussion: https://postgr.es/m/OSZPR01MB63104E7449DBE41932DB19F1FD1B9@OSZPR01MB6310.jpnprd01.prod.outlook.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	51b5834cd5	Provide options for postmaster to kill child processes with SIGABRT. ... The postmaster normally sends SIGQUIT to force-terminate its child processes after a child crash or immediate-stop request. If that doesn't result in child exit within a few seconds, we follow it up with SIGKILL. This patch provides GUC flags that allow either of these signals to be replaced with SIGABRT. On typically-configured Unix systems, that will result in a core dump being produced for each such child. This can be useful for debugging problems, although it's not something you'd want to have on in production due to the risk of disk space bloat from lots of core files. The old postmaster -T switch, which sent SIGSTOP in place of SIGQUIT, is changed to be the same as send_abort_for_crash. As far as I can tell from the code comments, the intent of that switch was just to block things for long enough to force core dumps manually, which seems like an unnecessary extra step. (Maybe at the time, there was no way to get most kernels to produce core files with per-PID names, requiring manual core file renaming after each one. But now it's surely the hard way.) I also took the opportunity to remove the old postmaster -n (skip shmem reinit) switch, which hasn't actually done anything in decades, though the documentation still claimed it did. Discussion: https://postgr.es/m/2251016.1668797294@sss.pgh.pa.us	3 years ago
Michael Paquier	d9d873bac6	Clean up some inconsistencies with GUC declarations ... This is similar to 7d25958, and this commit takes care of all the remaining inconsistencies between the initial value used in the C variable associated to a GUC and its default value stored in the GUC tables (as of pg_settings.boot_val). Some of the initial values of the GUCs updated rely on a compile-time default. These are refactored so as the GUC table and its C declaration use the same values. This makes everything consistent with other places, backend_flush_after, bgwriter_flush_after, port, checkpoint_flush_after doing so already, for example. Extracted from a larger patch by Peter Smith. The spots updated in the modules are from me. Author: Peter Smith, Michael Paquier Reviewed-by: Nathan Bossart, Tom Lane, Justin Pryzby Discussion: https://postgr.es/m/CAHut+PtHE0XSfjjRQ6D4v7+dqzCw=d+1a64ujra4EX8aoc_Z+w@mail.gmail.com	3 years ago
Michael Paquier	bdf9b60085	Fix comment in guc_tables.c ... s/ERROR_HANDLING/ERROR_HANDLING_OPTIONS/. Author: Peter Smith Discussion: https://postgr.es/m/CAHut+PtDj3CV+f0pVisc0XYMi2LHGBpQxQWtF0FjiSVN_nV17Q@mail.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