15 Commits (0b1fe1413ea84a381489ed1d1f718cb710229ab3)

Author	SHA1	Message	Date
Nathan Bossart	0b1fe1413e	Remove check hooks for GUCs that contribute to MaxBackends. ... Each of max_connections, max_worker_processes, autovacuum_max_workers, and max_wal_senders has a GUC check hook that verifies the sum of those GUCs does not exceed a hard-coded limit (see the comment for MAX_BACKENDS in postmaster.h). In general, the hooks effectively guard against egregious misconfigurations. However, this approach has some problems. Since these check hooks are called as each GUC is assigned its user-specified value, only one of the hooks will be called with all the relevant GUCs set. If one or more of the user-specified values are less than the initial values of the GUCs' underlying variables, false positives can occur. Furthermore, the error message emitted when one of the check hooks fails is not tremendously helpful. For example, the command $ pg_ctl -D . start -o "-c max_connections=262100 -c max_wal_senders=10000" fails with the following error: FATAL: invalid value for parameter "max_wal_senders": 10000 Fortunately, there is an extra copy of this check in InitializeMaxBackends() that we can rely on, so this commit removes the aforementioned GUC check hooks in favor of that one. It also enhances the error message to clearly show the values of the relevant GUCs and the hard-coded limit their sum may not exceed. The downside of this change is that server startup progresses further before failing due to such misconfigurations (thus taking longer), but these failures are expected to be rare, so we don't anticipate any real harm in practice. Reviewed-by: Tom Lane Discussion: https://postgr.es/m/ZnMr2k-Nk5vj7T7H%40nathan	1 year ago
Amit Kapila	2357c9223b	Rename standby_slot_names to synchronized_standby_slots. ... The standby_slot_names GUC allows the specification of physical standby slots that must be synchronized before the logical walsenders associated with logical failover slots. However, for this purpose, the GUC name is too generic. Author: Hou Zhijie Reviewed-by: Bertrand Drouvot, Masahiko Sawada Backpatch-through: 17 Discussion: https://postgr.es/m/ZnWeUgdHong93fQN@momjian.us	1 year ago
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
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
Bruce Momjian	29275b1d17	Update copyright for 2024 ... Reported-by: Michael Paquier Discussion: https://postgr.es/m/ZZKTDPxBBMt3C0J9@paquier.xyz Backpatch-through: 12	2 years ago
Amit Kapila	8bfb231b43	Prohibit max_slot_wal_keep_size to value other than -1 during upgrade. ... We don't want existing slots in the old cluster to get invalidated during the upgrade. During an upgrade, we set this variable to -1 via the command line in an attempt to prevent such invalidations, but users have ways to override it. This patch ensures the value is not overridden by the user. Author: Kyotaro Horiguchi Reviewed-by: Peter Smith, Alvaro Herrera Discussion: http://postgr.es/m/20231027.115759.2206827438943188717.horikyota.ntt@gmail.com	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
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
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	2 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	2 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	2 years ago
Bruce Momjian	c8e1ba736b	Update copyright for 2023 ... Backpatch-through: 11	3 years ago
Tom Lane	0a20ff54f5	Split up guc.c for better build speed and ease of maintenance. ... guc.c has grown to be one of our largest .c files, making it a bottleneck for compilation. It's also acquired a bunch of knowledge that'd be better kept elsewhere, because of our not very good habit of putting variable-specific check hooks here. Hence, split it up along these lines: * guc.c itself retains just the core GUC housekeeping mechanisms. * New file guc_funcs.c contains the SET/SHOW interfaces and some SQL-accessible functions for GUC manipulation. * New file guc_tables.c contains the data arrays that define the built-in GUC variables, along with some already-exported constant tables. * GUC check/assign/show hook functions are moved to the variable's home module, whenever that's clearly identifiable. A few hard- to-classify hooks ended up in commands/variable.c, which was already a home for miscellaneous GUC hook functions. To avoid cluttering a lot more header files with #include "guc.h", I also invented a new header file utils/guc_hooks.h and put all the GUC hook functions' declarations there, regardless of their originating module. That allowed removal of #include "guc.h" from some existing headers. The fallout from that (hopefully all caught here) demonstrates clearly why such inclusions are best minimized: there are a lot of files that, for example, were getting array.h at two or more levels of remove, despite not having any connection at all to GUCs in themselves. There is some very minor code beautification here, such as renaming a couple of inconsistently-named hook functions and improving some comments. But mostly this just moves code from point A to point B and deals with the ensuing needs for #include adjustments and exporting a few functions that previously weren't exported. Patch by me, per a suggestion from Andres Freund; thanks also to Michael Paquier for the idea to invent guc_funcs.c. Discussion: https://postgr.es/m/587607.1662836699@sss.pgh.pa.us	3 years ago