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47 hoursAllow passing a pointer to GetNamedDSMSegment()'s init callback.Nathan Bossart
This commit adds a new "void *arg" parameter to GetNamedDSMSegment() that is passed to the initialization callback function. This is useful for reusing an initialization callback function for multiple DSM segments. Author: Zsolt Parragi <zsolt.parragi@percona.com> Reviewed-by: Sami Imseih <samimseih@gmail.com> Discussion: https://postgr.es/m/CAN4CZFMjh8TrT9ZhWgjVTzBDkYZi2a84BnZ8bM%2BfLPuq7Cirzg%40mail.gmail.com
3 daysbufmgr: Add one-entry cache for private refcountAndres Freund
The private refcount entry for a buffer is often looked up repeatedly for the same buffer, e.g. to pin and then unpin a buffer. Benchmarking shows that it's worthwhile to have a one-entry cache for that case. With that cache in place, it's worth splitting GetPrivateRefCountEntry() into a small inline portion (for the cache hit case) and an out-of-line helper for the rest. This is helpful for some workloads today, but becomes more important in an upcoming patch that will utilize the private refcount infrastructure to also store whether the buffer is currently locked, as that increases the rate of lookups substantially. Reviewed-by: Melanie Plageman <melanieplageman@gmail.com> Discussion: https://postgr.es/m/6rgb2nvhyvnszz4ul3wfzlf5rheb2kkwrglthnna7qhe24onwr@vw27225tkyar
3 daysbufmgr: Separate keys for private refcount infrastructureAndres Freund
This makes lookups faster, due to allowing auto-vectorized lookups. It is also beneficial for an upcoming patch, independent of auto-vectorization, as the upcoming patch wants to track more information for each pinned buffer, making the existing loop, iterating over an array of PrivateRefCountEntry, more expensive due to increasing its size. Reviewed-by: Melanie Plageman <melanieplageman@gmail.com> Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff
5 daysReplace most StaticAssertStmt() with StaticAssertDecl()Peter Eisentraut
Similar to commit 75f49221c22, it is preferable to use StaticAssertDecl() instead of StaticAssertStmt() when possible. Discussion: https://www.postgresql.org/message-id/flat/CA%2BhUKGKvr0x_oGmQTUkx%3DODgSksT2EtgCA6LmGx_jQFG%3DsDUpg%40mail.gmail.com
6 daysFix some comments.Nathan Bossart
Like commit 123661427b, these were discovered while reviewing Aleksander Alekseev's proposed changes to pgindent.
6 daysFix comment on how temp files and subtransactions are handledHeikki Linnakangas
The comment was accurate a long time ago, but not any more. I failed to update the comment in commit ab3148b712.
7 daysUse palloc_object() and palloc_array(), the last changeMichael Paquier
This is the last batch of changes that have been suggested by the author, this part covering the non-trivial changes. Some of the changes suggested have been discarded as they seem to lead to more instructions generated, leaving the parts that can be qualified as in-place replacements. Similar work has been done in 1b105f9472bd, 0c3c5c3b06a3 and 31d3847a37be. Author: David Geier <geidav.pg@gmail.com> Discussion: https://postgr.es/m/ad0748d4-3080-436e-b0bc-ac8f86a3466a@gmail.com
7 daysFix some near-bugs related to ResourceOwner function argumentsHeikki Linnakangas
These functions took a ResourceOwner argument, but only checked if it was NULL, and then used CurrentResourceOwner for the actual work. Surely the intention was to use the passed-in resource owner. All current callers passed CurrentResourceOwner or NULL, so this has no consequences at the moment, but it's an accident waiting to happen for future caller and extensions. Author: Matthias van de Meent <boekewurm+postgres@gmail.com> Discussion: https://www.postgresql.org/message-id/CAEze2Whnfv8VuRZaohE-Af+GxBA1SNfD_rXfm84Jv-958UCcJA@mail.gmail.com Backpatch-through: 17
8 daysFix typo in commentHeikki Linnakangas
Author: Xuneng Zhou <xunengzhou@gmail.com> Reviewed-by: Chao Li <li.evan.chao@gmail.com> Discussion: https://www.postgresql.org/message-id/CABPTF7V8CbOXGePqrad6EH3Om7DRhNiO3C0rQ-62UuT7RdU-GQ@mail.gmail.com
8 daysUse palloc_object() and palloc_array() in backend codeMichael Paquier
The idea is to encourage more the use of these new routines across the tree, as these offer stronger type safety guarantees than palloc(). This batch of changes includes most of the trivial changes suggested by the author for src/backend/. A total of 334 files are updated here. Among these files, 48 of them have their build change slightly; these are caused by line number changes as the new allocation formulas are simpler, shaving around 100 lines of code in total. Similar work has been done in 0c3c5c3b06a3 and 31d3847a37be. Author: David Geier <geidav.pg@gmail.com> Discussion: https://postgr.es/m/ad0748d4-3080-436e-b0bc-ac8f86a3466a@gmail.com
9 daysRemove useless casts in format argumentsPeter Eisentraut
There were a number of useless casts in format arguments, either where the input to the cast was already in the right type, or seemingly uselessly casting between types instead of just using the right format placeholder to begin with. Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/07fa29f9-42d7-4aac-8834-197918cbbab6%40eisentraut.org
9 daysRemove unnecessary casts in printf format arguments (%zu/%zd)Peter Eisentraut
Many of these are probably left over from before use of %zu/%zd was portable. Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/07fa29f9-42d7-4aac-8834-197918cbbab6%40eisentraut.org
13 daysFix key size of PrivateRefCountHash.Nathan Bossart
The key is the first member of PrivateRefCountEntry, which has type Buffer. This commit changes the key size from sizeof(int32) to sizeof(Buffer). This appears to be an oversight in commit 4b4b680c3d, but it's of no consequence because Buffer has been a signed 32-bit integer for a long time. Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Discussion: https://postgr.es/m/aS77DTpl0fOkIKSZ%40ip-10-97-1-34.eu-west-3.compute.internal
14 daysRename BUFFERPIN wait event class to BUFFERAndres Freund
In an upcoming patch more wait events will be added to the wait event class (for buffer locking), making the current name too specific. Alternatively we could introduce a dedicated wait event class for those, but it seems somewhat confusing to have a BUFFERPIN and a BUFFER wait event class. Reviewed-by: Melanie Plageman <melanieplageman@gmail.com> Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff
14 daysbufmgr: Turn BUFFER_LOCK_* into an enumAndres Freund
It seems cleaner to use an enum to tie the different values together. It also helps to have a more descriptive type in the argument to various functions. Reviewed-by: Melanie Plageman <melanieplageman@gmail.com> Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff
2025-12-02Show size of DSAs and dshashes in pg_dsm_registry_allocations.Nathan Bossart
Presently, this view reports NULL for the size of DSAs and dshash tables because 1) the current backend might not be attached to them and 2) the registry doesn't save the pointers to the dsa_area or dshash_table in local memory. Also, the view doesn't show partially-initialized entries to avoid ambiguity, since those entries would report a NULL size as well. This commit introduces a function that looks up the size of a DSA given its handle (transiently attaching to the control segment if needed) and teaches pg_dsm_registry_allocations to use it to show the size of successfully-initialized DSA and dshash entries. Furthermore, the view now reports partially-initialized entries with a NULL size. Reviewed-by: Rahila Syed <rahilasyed90@gmail.com> Reviewed-by: Robert Haas <robertmhaas@gmail.com> Reviewed-by: Chao Li <li.evan.chao@gmail.com> Discussion: https://postgr.es/m/aSeEDeznAsHR1_YF%40nathan
2025-12-02Remove useless casting to same typePeter Eisentraut
This removes some casts where the input already has the same type as the type specified by the cast. Their presence could cause risks of hiding actual type mismatches in the future or silently discarding qualifiers. It also improves readability. Same kind of idea as 7f798aca1d5 and ef8fe693606. (This does not change all such instances, but only those hand-picked by the author.) Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Reviewed-by: Nathan Bossart <nathandbossart@gmail.com> Reviewed-by: Jacob Champion <jacob.champion@enterprisedb.com> Reviewed-by: Peter Eisentraut <peter@eisentraut.org> Discussion: https://www.postgresql.org/message-id/flat/aSQy2JawavlVlEB0%40ip-10-97-1-34.eu-west-3.compute.internal
2025-11-27Add routines for marking buffers dirty efficientlyMichael Paquier
This commit introduces new internal bufmgr routines for marking shared buffers as dirty: * MarkDirtyUnpinnedBuffer() * MarkDirtyRelUnpinnedBuffers() * MarkDirtyAllUnpinnedBuffers() These functions provide an efficient mechanism to respectively mark one buffer, all the buffers of a relation, or the entire shared buffer pool as dirty, something that can be useful to force patterns for the checkpointer. MarkDirtyUnpinnedBufferInternal(), an extra routine, is used by these three, to mark as dirty an unpinned buffer. They are intended as developer tools to manipulate buffer dirtiness in bulk, and will be used in a follow-up commit. Author: Nazir Bilal Yavuz <byavuz81@gmail.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Aidar Imamov <a.imamov@postgrespro.ru> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Reviewed-by: Joseph Koshakow <koshy44@gmail.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Reviewed-by: Yuhang Qiu <iamqyh@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CAN55FZ0h_YoSqqutxV6DES1RW8ig6wcA8CR9rJk358YRMxZFmw@mail.gmail.com
2025-11-26Teach DSM registry to retry entry initialization if needed.Nathan Bossart
If DSM registry entry initialization fails, backends could try to use an uninitialized DSM segment, DSA, or dshash table (since the entry is still added to the registry). To fix, restructure the code so that the registry retries initialization as needed. This commit also modifies pg_get_dsm_registry_allocations() to leave out partially-initialized entries, as they shouldn't have any allocated memory. DSM registry entry initialization shouldn't fail often in practice, but retrying was deemed better than leaving entries in a permanently failed state (as was done by commit 1165a933aa, which has since been reverted). Suggested-by: Robert Haas <robertmhaas@gmail.com> Reviewed-by: Robert Haas <robertmhaas@gmail.com> Discussion: https://postgr.es/m/E1vJHUk-006I7r-37%40gemulon.postgresql.org Backpatch-through: 17
2025-11-26Revert "Teach DSM registry to ERROR if attaching to an uninitialized entry."Nathan Bossart
This reverts commit 1165a933aa (and the corresponding commits on the back-branches). In a follow-up commit, we'll teach the registry to retry entry initialization instead of leaving it in a permanently failed state. Reviewed-by: Robert Haas <robertmhaas@gmail.com> Discussion: https://postgr.es/m/E1vJHUk-006I7r-37%40gemulon.postgresql.org Backpatch-through: 17
2025-11-26Remove a few unused struct members.Nathan Bossart
Oversights in commits ab9e0e718a, f3049a603a, and 247ce06b88. Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Discussion: https://postgr.es/m/aScUuBSawPWogUxs%40ip-10-97-1-34.eu-west-3.compute.internal
2025-11-24lwlock: Fix, currently harmless, bug in LWLockWakeup()Andres Freund
Accidentally the code in LWLockWakeup() checked the list of to-be-woken up processes to see if LW_FLAG_HAS_WAITERS should be unset. That means that HAS_WAITERS would not get unset immediately, but only during the next, unnecessary, call to LWLockWakeup(). Luckily, as the code stands, this is just a small efficiency issue. However, if there were (as in a patch of mine) a case in which LWLockWakeup() would not find any backend to wake, despite the wait list not being empty, we'd wrongly unset LW_FLAG_HAS_WAITERS, leading to potentially hanging. While the consequences in the backbranches are limited, the code as-is confusing, and it is possible that there are workloads where the additional wait list lock acquisitions hurt, therefore backpatch. Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff Backpatch-through: 14
2025-11-24postgres: Use pg_{add,mul}_size_overflow()Jacob Champion
The backend implementations of add_size() and mul_size() can now make use of the APIs provided in common/int.h. Reviewed-by: Chao Li <li.evan.chao@gmail.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Discussion: https://postgr.es/m/CAOYmi%2B%3D%2BpqUd2MUitvgW1pAJuXgG_TKCVc3_Ek7pe8z9nkf%2BAg%40mail.gmail.com
2025-11-21Remove useless casts to (void *)Peter Eisentraut
Their presence causes (small) risks of hiding actual type mismatches or silently discarding qualifiers. Some have been missed in 7f798aca1d5 and some are new ones along the same lines. Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/aR8Yv%2BuATLKbJCgI%40ip-10-97-1-34.eu-west-3.compute.internal
2025-11-21C11 alignas instead of unionsPeter Eisentraut
This changes a few union members that only existed to ensure alignments and replaces them with the C11 alignas specifier. This change only uses fundamental alignments (meaning approximately alignments of basic types), which all C11 compilers must support. There are opportunities for similar changes using extended alignments, for example in PGIOAlignedBlock, but these are not necessarily supported by all compilers, so they are kept as a separate change. Reviewed-by: Chao Li <li.evan.chao@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/46f05236-d4d4-4b4e-84d4-faa500f14691%40eisentraut.org
2025-11-13Add some missing #include <limits.h>.Thomas Munro
These files relied on transitive inclusion via port/atomics.h for constants CHAR_BIT and INT_MAX. Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Discussion: https://postgr.es/m/536409d2-c9df-4ef3-808d-1ffc3182868c@iki.fi
2025-11-13Replace off_t by pgoff_t in I/O routinesMichael Paquier
PostgreSQL's Windows port has never been able to handle files larger than 2GB due to the use of off_t for file offsets, only 32-bit on Windows. This causes signed integer overflow at exactly 2^31 bytes when trying to handle files larger than 2GB, for the routines touched by this commit. Note that large files are forbidden by ./configure (3c6248a828af) and meson (recent change, see 79cd66f28c65). This restriction also exists in v16 and older versions for the now-dead MSVC scripts. The code base already defines pgoff_t as __int64 (64-bit) on Windows for this purpose, and some function declarations in headers use it, but many internals still rely on off_t. This commit switches more routines to use pgoff_t, offering more portability, for areas mainly related to file extensions and storage. These are not critical for WAL segments yet, which have currently a maximum size allowed of 1GB (well, this opens the door at allowing a larger size for them). This matters more for segment files if we want to lift the large file restriction in ./configure and meson in the future, which would make sense to remove once/if all traces of off_t are gone from the tree. This can additionally matter for out-of-core code that may want files larger than 2GB in places where off_t is four bytes in size. Note that off_t is still used in other parts of the tree like buffile.c, WAL sender/receiver, base backup, pg_combinebackup, etc. These other code paths can be addressed separately, and their update will be required if we want to remove the large file restriction in the future. This commit is a good first cut in itself towards more portability, hopefully. On Unix-like systems, pgoff_t is defined as off_t, so this change only affects Windows behavior. Author: Bryan Green <dbryan.green@gmail.com> Reviewed-by: Thomas Munro <thomas.munro@gmail.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Discussion: https://postgr.es/m/0f238ff4-c442-42f5-adb8-01b762c94ca1@gmail.com
2025-11-12Teach DSM registry to ERROR if attaching to an uninitialized entry.Nathan Bossart
If DSM entry initialization fails, backends could try to use an uninitialized DSM segment, DSA, or dshash table (since the entry is still added to the registry). To fix, keep track of whether initialization completed, and ERROR if a backend tries to attach to an uninitialized entry. We could instead retry initialization as needed, but that seemed complicated, error prone, and unlikely to help most cases. Furthermore, such problems probably indicate a coding error. Reported-by: Alexander Lakhin <exclusion@gmail.com> Reviewed-by: Sami Imseih <samimseih@gmail.com> Discussion: https://postgr.es/m/dd36d384-55df-4fc2-825c-5bc56c950fa9%40gmail.com Backpatch-through: 17
2025-11-08Remove blank line in C code.Bruce Momjian
Was added in commit 5e89985928795f243dc287210c2aa016dfd00bfe. Reported-by: Ashutosh Bapat Author: Ashutosh Bapat Discussion: https://postgr.es/m/CAExHW5tba_biyuMrd_iPVzq-+XvsMdPcEnjQ+d+__V=cjYj8Pg@mail.gmail.com Backpatch-through: master
2025-11-06bufmgr: Use atomic sub for unpinning buffersAndres Freund
The prior commit made it legal to modify BufferDesc.state while the buffer header spinlock is held. This allows us to replace the CAS loop inUnpinBufferNoOwner() with an atomic sub. This improves scalability significantly. See the prior commits for more background. Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com> Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff
2025-11-06bufmgr: Allow some buffer state modifications while holding header lockAndres Freund
Until now BufferDesc.state was not allowed to be modified while the buffer header spinlock was held. This meant that operations like unpinning buffers needed to use a CAS loop, waiting for the buffer header spinlock to be released before updating. The benefit of that restriction is that it allowed us to unlock the buffer header spinlock with just a write barrier and an unlocked write (instead of a full atomic operation). That was important to avoid regressions in 48354581a49c. However, since then the hottest buffer header spinlock uses have been replaced with atomic operations (in particular, the most common use of PinBuffer_Locked(), in GetVictimBuffer() (formerly in BufferAlloc()), has been removed in 5e899859287). This change will allow, in a subsequent commit, to release buffer pins with a single atomic-sub operation. This previously was not possible while such operations were not allowed while the buffer header spinlock was held, as an atomic-sub would not have allowed a race-free check for the buffer header lock being held. Using atomic-sub to unpin buffers is a nice scalability win, however it is not the primary motivation for this change (although it would be sufficient). The primary motivation is that we would like to merge the buffer content lock into BufferDesc.state, which will result in more frequent changes of the state variable, which in some situations can cause a performance regression, due to an increased CAS failure rate when unpinning buffers. The regression entirely vanishes when using atomic-sub. Naively implementing this would require putting CAS loops in every place modifying the buffer state while holding the buffer header lock. To avoid that, introduce UnlockBufHdrExt(), which can set/add flags as well as the refcount, together with releasing the lock. Reviewed-by: Robert Haas <robertmhaas@gmail.com> Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com> Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff
2025-11-06Use XLogRecPtrIsValid() in various placesÁlvaro Herrera
Now that commit 06edbed47862 has introduced XLogRecPtrIsValid(), we can use that instead of: - XLogRecPtrIsInvalid() - direct comparisons with InvalidXLogRecPtr - direct comparisons with literal 0 This makes the code more consistent. Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Discussion: https://postgr.es/m/aQB7EvGqrbZXrMlg@ip-10-97-1-34.eu-west-3.compute.internal
2025-11-06Refactor shared memory allocation for semaphoresHeikki Linnakangas
Before commit e25626677f, spinlocks were implemented using semaphores on some platforms (--disable-spinlocks). That made it necessary to initialize semaphores early, before any spinlocks could be used. Now that we don't support --disable-spinlocks anymore, we can allocate the shared memory needed for semaphores the same way as other shared memory structures. Since the semaphores are used only in the PGPROC array, move the semaphore shmem size estimation and initialization calls to ProcGlobalShmemSize() and InitProcGlobal(). Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Discussion: https://www.postgresql.org/message-id/CAExHW5seSZpPx-znjidVZNzdagGHOk06F+Ds88MpPUbxd1kTaA@mail.gmail.com
2025-11-06Add comment to explain why PGReserveSemaphores() is called earlyHeikki Linnakangas
Before commit e25626677f, PGReserveSemaphores() had to be called before SpinlockSemaInit() because spinlocks were implemented using semaphores on some platforms (--disable-spinlocks). Add a comment explaining that. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Discussion: https://www.postgresql.org/message-id/CAExHW5seSZpPx-znjidVZNzdagGHOk06F+Ds88MpPUbxd1kTaA@mail.gmail.com Backpatch-to: 18
2025-11-05Implement WAIT FOR commandAlexander Korotkov
WAIT FOR is to be used on standby and specifies waiting for the specific WAL location to be replayed. This option is useful when the user makes some data changes on primary and needs a guarantee to see these changes are on standby. WAIT FOR needs to wait without any snapshot held. Otherwise, the snapshot could prevent the replay of WAL records, implying a kind of self-deadlock. This is why separate utility command seems appears to be the most robust way to implement this functionality. It's not possible to implement this as a function. Previous experience shows that stored procedures also have limitation in this aspect. Discussion: https://www.postgresql.org/message-id/flat/CAPpHfdsjtZLVzxjGT8rJHCYbM0D5dwkO+BBjcirozJ6nYbOW8Q@mail.gmail.com Discussion: https://www.postgresql.org/message-id/flat/CABPTF7UNft368x-RgOXkfj475OwEbp%2BVVO-wEXz7StgjD_%3D6sw%40mail.gmail.com Author: Kartyshov Ivan <i.kartyshov@postgrespro.ru> Author: Alexander Korotkov <aekorotkov@gmail.com> Author: Xuneng Zhou <xunengzhou@gmail.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com> Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Reviewed-by: Alexander Lakhin <exclusion@gmail.com> Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Reviewed-by: Euler Taveira <euler@eulerto.com> Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Reviewed-by: jian he <jian.universality@gmail.com> Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com>
2025-11-05Add infrastructure for efficient LSN waitingAlexander Korotkov
Implement a new facility that allows processes to wait for WAL to reach specific LSNs, both on primary (waiting for flush) and standby (waiting for replay) servers. The implementation uses shared memory with per-backend information organized into pairing heaps, allowing O(1) access to the minimum waited LSN. This enables fast-path checks: after replaying or flushing WAL, the startup process or WAL writer can quickly determine if any waiters need to be awakened. Key components: - New xlogwait.c/h module with WaitForLSNReplay() and WaitForLSNFlush() - Separate pairing heaps for replay and flush waiters - WaitLSN lightweight lock for coordinating shared state - Wait events WAIT_FOR_WAL_REPLAY and WAIT_FOR_WAL_FLUSH for monitoring This infrastructure can be used by features that need to wait for WAL operations to complete. Discussion: https://www.postgresql.org/message-id/flat/CAPpHfdsjtZLVzxjGT8rJHCYbM0D5dwkO+BBjcirozJ6nYbOW8Q@mail.gmail.com Discussion: https://www.postgresql.org/message-id/flat/CABPTF7UNft368x-RgOXkfj475OwEbp%2BVVO-wEXz7StgjD_%3D6sw%40mail.gmail.com Author: Kartyshov Ivan <i.kartyshov@postgrespro.ru> Author: Alexander Korotkov <aekorotkov@gmail.com> Author: Xuneng Zhou <xunengzhou@gmail.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com> Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Reviewed-by: Alexander Lakhin <exclusion@gmail.com> Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Reviewed-by: Euler Taveira <euler@eulerto.com> Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com>
2025-11-05aio: Improve assertions related to io_methodAndres Freund
First, the assertions in assign_io_method() were the wrong way round. Second, the lengthof() assertion checked the length of io_method_options, which is the wrong array to check and is always longer than pgaio_method_ops_table. While add it, add a static assert to ensure pgaio_method_ops_table and io_method_options stay in sync. Per coverity and Tom Lane. Reported-by: Tom Lane <tgl@sss.pgh.pa.us> Backpatch-through: 18
2025-11-04Add CHECK_FOR_INTERRUPTS in Evict{Rel,All}UnpinnedBuffers.Masahiko Sawada
This commit adds CHECK_FOR_INTERRUPTS to the shared buffer iteration loops in EvictRelUnpinnedBuffers and EvictAllUnpinnedBuffers. These functions, used by pg_buffercache's pg_buffercache_evict_relation and pg_buffercache_evict_all, can now be interrupted during long-running operations. Backpatch to version 18, where these functions and their corresponding pg_buffercache functions were introduced. Author: Yuhang Qiu <iamqyh@gmail.com> Discussion: https://postgr.es/m/8DC280D4-94A2-4E7B-BAB9-C345891D0B78%40gmail.com Backpatch-through: 18
2025-10-30Mark ItemPointer arguments as const throughoutPeter Eisentraut
This is a follow up 991295f. I searched over src/ and made all ItemPointer arguments as const as much as possible. Note: We cut out from the original patch the pieces that would have created incompatibilities in the index or table AM APIs. Those could be considered separately. Author: Chao Li <li.evan.chao@gmail.com> Discussion: https://www.postgresql.org/message-id/CAEoWx2nBaypg16Z5ciHuKw66pk850RFWw9ACS2DqqJ_AkKeRsw%40mail.gmail.com
2025-10-30const-qualify ItemPointer comparison functionsPeter Eisentraut
Add const qualifiers to ItemPointerEquals() and ItemPointerCompare(). This will allow further changes up the stack. It also complements commit aeb767ca0b0, as we now have all of itemptr.h appropriately const-qualified. Author: Chao Li <li.evan.chao@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAEoWx2nBaypg16Z5ciHuKw66pk850RFWw9ACS2DqqJ_AkKeRsw@mail.gmail.com
2025-10-27Fix a couple of comments.Nathan Bossart
These were discovered while reviewing Aleksander Alekseev's proposed changes to pgindent. Oversights in commits 393e0d2314 and 25a30bbd42. Discussion: https://postgr.es/m/aP-H6kSsGOxaB21k%40nathan
2025-10-27Remove Item typePeter Eisentraut
This type is just char * underneath, it provides no real value, no type safety, and just makes the code one level more mysterious. It is more idiomatic to refer to blobs of memory by a combination of void * and size_t, so change it to that. Also, since this type hides the pointerness, we can't apply qualifiers to what is pointed to, which requires some unconstify nonsense. This change allows fixing that. Extension code that uses the Item type can change its code to use void * to be backward compatible. Reviewed-by: Nathan Bossart <nathandbossart@gmail.com> Reviewed-by: Peter Geoghegan <pg@bowt.ie> Discussion: https://www.postgresql.org/message-id/flat/c75cccf5-5709-407b-a36a-2ae6570be766@eisentraut.org
2025-10-21Make smgr access for a BufferManagerRelation safer in relcache invalÁlvaro Herrera
Currently there's no bug, because we have no code path where we invalidate relcache entries where it'd cause a problem. But it's more robust to do it this way in case we introduce such a path later, as some Postgres forks reportedly already have. Author: Daniil Davydov <3danissimo@gmail.com> Reviewed-by: Stepan Neretin <slpmcf@gmail.com> Discussion: https://postgr.es/m/CAJDiXgj3FNzAhV+jjPqxMs3jz=OgPohsoXFj_fh-L+nS+13CKQ@mail.gmail.com
2025-10-21Fix comment in pg_get_shmem_allocations_numa()Michael Paquier
The comment fixed in this commit described the function as dealing with database blocks, but in reality it processes shared memory allocations. Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Discussion: https://postgr.es/m/aH4DDhdiG9Gi0rG7@ip-10-97-1-34.eu-west-3.compute.internal Backpatch-through: 18
2025-10-19Add static assertion that RELSEG_SIZE fits in an int.Tom Lane
Our configure script intended to ensure this, but it supposed that expr(1) would report an error for integer overflow. Maybe that was true when the code was written (commit 3c6248a82 of 2008-05-02), but all the modern expr's I tried will deliver bigger-than-int32 results without complaint. Moreover, if you use --with-segsize-blocks then there's no check at all. Ideally we'd add a test in configure itself to check that the value fits in int, but to do that we'd need to suppose that test(1) handles bigger-than-int32 numbers correctly. Probably modern ones do, but that's an assumption I could do without; and I'm not too trusting about meson either. Instead, let's install a static assertion, so that even people who ignore all the compiler warnings you get from such values will be forced to confront the fact that it won't work. This has been hazardous for awhile, but given that we hadn't heard a complaint about it till now, I don't feel a need to back-patch. Reported-by: Casey Shobe <casey.allen.shobe@icloud.com> Author: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/C5DC82D6-C76D-4E8F-BC2E-DF03EFC4FA24@icloud.com
2025-10-09bufmgr: Fix valgrind checking for buffers pinned in StrategyGetBuffer()Andres Freund
In 5e899859287 I made StrategyGetBuffer() pin buffers with a single CAS, instead of using PinBuffer_Locked(). Unfortunately I missed that PinBuffer_Locked() marked the page as defined for valgrind. Fix this oversight by centralizing the valgrind initialization into TrackNewBufferPin(), which also allows us to reduce the number of places doing VALGRIND_MAKE_MEM_DEFINED. Per buildfarm animal skink and Amit Langote. Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff Discussion: https://postgr.es/m/CA+HiwqGKJ6nEXEPQW7EpykVsEtzxp5-up_xhtcUAkWFtATVQvQ@mail.gmail.com
2025-10-08bufmgr: Don't lock buffer header in StrategyGetBuffer()Andres Freund
Previously StrategyGetBuffer() acquired the buffer header spinlock for every buffer, whether it was reusable or not. If reusable, it'd be returned, with the lock held, to GetVictimBuffer(), which then would pin the buffer with PinBuffer_Locked(). That's somewhat violating the spirit of the guidelines for holding spinlocks (i.e. that they are only held for a few lines of consecutive code) and necessitates using PinBuffer_Locked(), which scales worse than PinBuffer() due to holding the spinlock. This alone makes it worth changing the code. However, the main reason to change this is that a future commit will make PinBuffer_Locked() slower (due to making UnlockBufHdr() slower), to gain scalability for the much more common case of pinning a pre-existing buffer. By pinning the buffer with a single atomic operation, iff the buffer is reusable, we avoid any potential regression for miss-heavy workloads. There strictly are fewer atomic operations for each potential buffer after this change. The price for this improvement is that freelist.c needs two CAS loops and needs to be able to set up the resource accounting for pinned buffers. The latter is achieved by exposing a new function for that purpose from bufmgr.c, that seems better than exposing the entire private refcount infrastructure. The improvement seems worth the complexity. Reviewed-by: Robert Haas <robertmhaas@gmail.com> Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com> Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff
2025-10-08bufmgr: fewer calls to BufferDescriptorGetContentLockAndres Freund
We're planning to merge buffer content locks into BufferDesc.state. To reduce the size of that patch, centralize calls to BufferDescriptorGetContentLock(). The biggest part of the change is in assertions, by introducing BufferIsLockedByMe[InMode]() (and removing BufferIsExclusiveLocked()). This seems like an improvement even without aforementioned plans. Additionally replace some direct calls to LWLockAcquire() with calls to LockBuffer(). Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com> Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff
2025-10-08bufmgr: Fix signedness of mask variable in BufferSync()Andres Freund
BM_PERMANENT is defined as 1U<<31, which is a negative number when interpreted as a signed integer. Unfortunately the mask variable in BufferSync() was signed. This has been wrong for a long time, but failed to fail, due to integer conversion rules. However, in an upcoming patch the width of the state variable will be increased, with the wrong signedness leading to never flushing permanent buffers - luckily caught in a test. It seems better to fix this separately, instead of doing so as part of a large, otherwise mechanical, patch. Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com> Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff
2025-10-08bufmgr: Introduce FlushUnlockedBufferAndres Freund
There were several copies of code locking a buffer, flushing its contents, and unlocking the buffer. It seems worth centralizing that into a helper function. Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com> Discussion: https://postgr.es/m/fvfmkr5kk4nyex56ejgxj3uzi63isfxovp2biecb4bspbjrze7@az2pljabhnff