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* Remove unused #include's from backend .c filesPeter Eisentraut2024-10-27
| | | | | | | | as determined by IWYU These are mostly issues that are new since commit dbbca2cf299. Discussion: https://www.postgresql.org/message-id/flat/0df1d5b1-8ca8-4f84-93be-121081bde049%40eisentraut.org
* Move LSN waiting declarations and definitions to better placeAlexander Korotkov2024-10-24
| | | | | | | | | | | | | | | | | | | 3c5db1d6b implemented the pg_wal_replay_wait() stored procedure. Due to the patch development history, the implementation resided in src/backend/commands/waitlsn.c (src/include/commands/waitlsn.h for headers). 014f9f34d moved pg_wal_replay_wait() itself to src/backend/access/transam/xlogfuncs.c near to the WAL-manipulation functions. But most of the implementation stayed in place. The code in src/backend/commands/waitlsn.c has nothing to do with commands, but is related to WAL. So, this commit moves this code into src/backend/access/transam/xlogwait.c (src/include/access/xlogwait.h for headers). Reported-by: Peter Eisentraut Discussion: https://postgr.es/m/18c0fa64-0475-415e-a1bd-665d922c5201%40eisentraut.org Reviewed-by: Pavel Borisov
* Update outdated comment on WAL-logged locks with invalid XIDHeikki Linnakangas2024-10-21
| | | | | | We haven't generated those for a long time. Discussion: https://www.postgresql.org/message-id/b439edfc-c5e5-43a9-802d-4cb51ec20646@iki.fi
* Use an shmem_exit callback to remove backend from PMChildFlags on exitHeikki Linnakangas2024-10-08
| | | | | | | | | | | | This seems nicer than having to duplicate the logic between InitProcess() and ProcKill() for which child processes have a PMChildFlags slot. Move the MarkPostmasterChildActive() call earlier in InitProcess(), out of the section protected by the spinlock. Reviewed-by: Andres Freund <andres@anarazel.de> Discussion: https://www.postgresql.org/message-id/a102f15f-eac4-4ff2-af02-f9ff209ec66f@iki.fi
* Increase the number of fast-path lock slotsTomas Vondra2024-09-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Replace the fixed-size array of fast-path locks with arrays, sized on startup based on max_locks_per_transaction. This allows using fast-path locking for workloads that need more locks. The fast-path locking introduced in 9.2 allowed each backend to acquire a small number (16) of weak relation locks cheaply. If a backend needs to hold more locks, it has to insert them into the shared lock table. This is considerably more expensive, and may be subject to contention (especially on many-core systems). The limit of 16 fast-path locks was always rather low, because we have to lock all relations - not just tables, but also indexes, views, etc. For planning we need to lock all relations that might be used in the plan, not just those that actually get used in the final plan. So even with rather simple queries and schemas, we often need significantly more than 16 locks. As partitioning gets used more widely, and the number of partitions increases, this limit is trivial to hit. Complex queries may easily use hundreds or even thousands of locks. For workloads doing a lot of I/O this is not noticeable, but for workloads accessing only data in RAM, the access to the shared lock table may be a serious issue. This commit removes the hard-coded limit of the number of fast-path locks. Instead, the size of the fast-path arrays is calculated at startup, and can be set much higher than the original 16-lock limit. The overall fast-path locking protocol remains unchanged. The variable-sized fast-path arrays can no longer be part of PGPROC, but are allocated as a separate chunk of shared memory and then references from the PGPROC entries. The fast-path slots are organized as a 16-way set associative cache. You can imagine it as a hash table of 16-slot "groups". Each relation is mapped to exactly one group using hash(relid), and the group is then processed using linear search, just like the original fast-path cache. With only 16 entries this is cheap, with good locality. Treating this as a simple hash table with open addressing would not be efficient, especially once the hash table gets almost full. The usual remedy is to grow the table, but we can't do that here easily. The access would also be more random, with worse locality. The fast-path arrays are sized using the max_locks_per_transaction GUC. We try to have enough capacity for the number of locks specified in the GUC, using the traditional 2^n formula, with an upper limit of 1024 lock groups (i.e. 16k locks). The default value of max_locks_per_transaction is 64, which means those instances will have 64 fast-path slots. The main purpose of the max_locks_per_transaction GUC is to size the shared lock table. It is often set to the "average" number of locks needed by backends, with some backends using significantly more locks. This should not be a major issue, however. Some backens may have to insert locks into the shared lock table, but there can't be too many of them, limiting the contention. The only solution is to increase the GUC, even if the shared lock table already has sufficient capacity. That is not free, especially in terms of memory usage (the shared lock table entries are fairly large). It should only happen on machines with plenty of memory, though. In the future we may consider a separate GUC for the number of fast-path slots, but let's try without one first. Reviewed-by: Robert Haas, Jakub Wartak Discussion: https://postgr.es/m/510b887e-c0ce-4a0c-a17a-2c6abb8d9a5c@enterprisedb.com
* Rename some shared memory initialization routinesHeikki Linnakangas2024-08-29
| | | | | | | | | | | | | | | | To make them follow the usual naming convention where FoobarShmemSize() calculates the amount of shared memory needed by Foobar subsystem, and FoobarShmemInit() performs the initialization. I didn't rename CreateLWLocks() and InitShmmeIndex(), because they are a little special. They need to be called before any of the other ShmemInit() functions, because they set up the shared memory bookkeeping itself. I also didn't rename InitProcGlobal(), because unlike other Shmeminit functions, it's not called by individual backends. Reviewed-by: Andreas Karlsson Discussion: https://www.postgresql.org/message-id/c09694ff-2453-47e5-b26c-32a16cd75ce6@iki.fi
* Refactor lock manager initialization to make it a bit less specialHeikki Linnakangas2024-08-29
| | | | | | | | | | Split the shared and local initialization to separate functions, and follow the common naming conventions. With this, we no longer create the LockMethodLocalHash hash table in the postmaster process, which was always pointless. Reviewed-by: Andreas Karlsson Discussion: https://www.postgresql.org/message-id/c09694ff-2453-47e5-b26c-32a16cd75ce6@iki.fi
* Implement pg_wal_replay_wait() stored procedureAlexander Korotkov2024-08-02
| | | | | | | | | | | | | | | | | | | | | | | | | | pg_wal_replay_wait() 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. The queue of waiters is stored in the shared memory as an LSN-ordered pairing heap, where the waiter with the nearest LSN stays on the top. During the replay of WAL, waiters whose LSNs have already been replayed are deleted from the shared memory pairing heap and woken up by setting their latches. pg_wal_replay_wait() 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 it is only possible to implement pg_wal_replay_wait() as a procedure working without an active snapshot, not a function. Catversion is bumped. Discussion: https://postgr.es/m/eb12f9b03851bb2583adab5df9579b4b%40postgrespro.ru Author: Kartyshov Ivan, Alexander Korotkov Reviewed-by: Michael Paquier, Peter Eisentraut, Dilip Kumar, Amit Kapila Reviewed-by: Alexander Lakhin, Bharath Rupireddy, Euler Taveira Reviewed-by: Heikki Linnakangas, Kyotaro Horiguchi
* Remove --disable-spinlocks.Thomas Munro2024-07-30
| | | | | | | | | | A later change will require atomic support, so it wouldn't make sense for a hypothetical new system not to be able to implement spinlocks. Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (concept, not the patch) Reviewed-by: Andres Freund <andres@anarazel.de> (concept, not the patch) Discussion: https://postgr.es/m/3351991.1697728588%40sss.pgh.pa.us
* Fix double-release of spinlockHeikki Linnakangas2024-07-29
| | | | | | | | | | | | | | | | Commit 9d9b9d46f3 added spinlocks to protect the fields in ProcSignal flags, but in EmitProcSignalBarrier(), the spinlock was released twice. With most spinlock implementations, releasing a lock that's not held is not easy to notice, because most of the time it does nothing, but if the spinlock was concurrently acquired by another process, it could lead to more serious issues. Fortunately, with the --disable-spinlocks emulation implementation, it caused more visible failures. In the passing, fix a type in comment and add an assertion that the procNumber passed to SendProcSignal looks valid. Discussion: https://www.postgresql.org/message-id/b8ce284c-18a2-4a79-afd3-1991a2e7d246@iki.fi
* Fix compiler warning/error about typedef redefinitionsHeikki Linnakangas2024-07-29
| | | | | | Per buildfarm member 'sifaka': procsignal.c:87:3: error: redefinition of typedef 'ProcSignalHeader' is a C11 feature [-Werror,-Wtypedef-redefinition]
* Move cancel key generation to after forking the backendHeikki Linnakangas2024-07-29
| | | | | | | | | | | | | | | | | | | | | | Move responsibility of generating the cancel key to the backend process. The cancel key is now generated after forking, and the backend advertises it in the ProcSignal array. When a cancel request arrives, the backend handling it scans the ProcSignal array to find the target pid and cancel key. This is similar to how this previously worked in the EXEC_BACKEND case with the ShmemBackendArray, just reusing the ProcSignal array. One notable change is that we no longer generate cancellation keys for non-backend processes. We generated them before just to prevent a malicious user from canceling them; the keys for non-backend processes were never actually given to anyone. There is now an explicit flag indicating whether a process has a valid key or not. I wrote this originally in preparation for supporting longer cancel keys, but it's a nice cleanup on its own. Reviewed-by: Jelte Fennema-Nio Discussion: https://www.postgresql.org/message-id/508d0505-8b7a-4864-a681-e7e5edfe32aa@iki.fi
* Introduce num_os_semaphores GUC.Nathan Bossart2024-07-26
| | | | | | | | | | | | | | | | | | | The documentation for System V IPC parameters provides complicated formulas to determine the appropriate values for SEMMNI and SEMMNS. Furthermore, these formulas have often been wrong because folks forget to update them (e.g., when adding a new auxiliary process). This commit introduces a new runtime-computed GUC named num_os_semaphores that reports the number of semaphores needed for the configured number of allowed connections, worker processes, etc. This new GUC allows us to simplify the formulas in the documentation, and it should help prevent future inaccuracies. Like the other runtime-computed GUCs, users can view it with "postgres -C" before starting the server, which is useful for preconfiguring the necessary operating system resources. Reviewed-by: Tom Lane, Sami Imseih, Andres Freund, Robert Haas Discussion: https://postgr.es/m/20240517164452.GA1914161%40nathanxps13
* Fix lost Windows socket EOF events.Thomas Munro2024-07-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Winsock only signals an FD_CLOSE event once if the other end of the socket shuts down gracefully. Because each WaitLatchOrSocket() call constructs and destroys a new event handle every time, with unlucky timing we can lose it and hang. We get away with this only if the other end disconnects non-gracefully, because FD_CLOSE is repeatedly signaled in that case. To fix this design flaw in our Windows socket support fundamentally, we'd probably need to rearchitect it so that a single event handle exists for the lifetime of a socket, or switch to completely different multiplexing or async I/O APIs. That's going to be a bigger job and probably wouldn't be back-patchable. This brute force kludge closes the race by explicitly polling with MSG_PEEK before sleeping. Back-patch to all supported releases. This should hopefully clear up some random build farm and CI hang failures reported over the years. It might also allow us to try using graceful shutdown in more places again (reverted in commit 29992a6) to fix instability in the transmission of FATAL error messages, but that isn't done by this commit. Reported-by: Tom Lane <tgl@sss.pgh.pa.us> Tested-by: Alexander Lakhin <exclusion@gmail.com> Discussion: https://postgr.es/m/176008.1715492071%40sss.pgh.pa.us
* Introduce pg_signal_autovacuum_worker.Nathan Bossart2024-07-09
| | | | | | | | | | | | | | | | Since commit 3a9b18b309, roles with privileges of pg_signal_backend cannot signal autovacuum workers. Many users treated the ability to signal autovacuum workers as a feature instead of a bug, so we are reintroducing it via a new predefined role. Having privileges of this new role, named pg_signal_autovacuum_worker, only permits signaling autovacuum workers. It does not permit signaling other types of superuser backends. Bumps catversion. Author: Kirill Reshke Reviewed-by: Anthony Leung, Michael Paquier, Andrey Borodin Discussion: https://postgr.es/m/CALdSSPhC4GGmbnugHfB9G0%3DfAxjCSug_-rmL9oUh0LTxsyBfsg%40mail.gmail.com
* Remove an extra period in code commentRichard Guo2024-07-08
| | | | | Author: Junwang Zhao Discussion: https://postgr.es/m/CAEG8a3L9GgfKc+XT+NMHPY7atAOVYqjUqKEFQKhcPHFYRW=PuQ@mail.gmail.com
* Optimize memory access in GetRunningTransactionData()Alexander Korotkov2024-07-04
| | | | | | | | | | e85662df44 made GetRunningTransactionData() calculate the oldest running transaction id within the current database. This commit optimized this calculation by performing a cheap transaction id comparison before fetching the process database id, while the latter could cause extra cache misses. Reported-by: Noah Misch Discussion: https://postgr.es/m/20240630231816.bf.nmisch%40google.com
* Fix typo in GetRunningTransactionData()Alexander Korotkov2024-07-04
| | | | | | | | | | | | e85662df44 made GetRunningTransactionData() calculate the oldest running transaction id within the current database. However, because of the typo, the new code uses oldestRunningXid instead of oldestDatabaseRunningXid in comparison before updating oldestDatabaseRunningXid. This commit fixes that issue. Reported-by: Noah Misch Discussion: https://postgr.es/m/20240630231816.bf.nmisch%40google.com Backpatch-through: 17
* Add wait event type "InjectionPoint", a custom type like "Extension".Noah Misch2024-06-27
| | | | | | | | | Both injection points and customization of type "Extension" are new in v17, so this just changes a detail of an unreleased feature. Reported by Robert Haas. Reviewed by Michael Paquier. Discussion: https://postgr.es/m/CA+TgmobfMU5pdXP36D5iAwxV5WKE_vuDLtp_1QyH+H5jMMt21g@mail.gmail.com
* Fix MVCC bug with prepared xact with subxacts on standbyHeikki Linnakangas2024-06-27
| | | | | | | | | | | | | | | | | | We did not recover the subtransaction IDs of prepared transactions when starting a hot standby from a shutdown checkpoint. As a result, such subtransactions were considered as aborted, rather than in-progress. That would lead to hint bits being set incorrectly, and the subtransactions suddenly becoming visible to old snapshots when the prepared transaction was committed. To fix, update pg_subtrans with prepared transactions's subxids when starting hot standby from a shutdown checkpoint. The snapshots taken from that state need to be marked as "suboverflowed", so that we also check the pg_subtrans. Backport to all supported versions. Discussion: https://www.postgresql.org/message-id/6b852e98-2d49-4ca1-9e95-db419a2696e0@iki.fi
* Fix documentation about DROP DATABASE FORCE process termination rights.Noah Misch2024-05-16
| | | | | | | | | | | Specifically, it terminates a background worker even if the caller couldn't terminate the background worker with pg_terminate_backend(). Commit 3a9b18b3095366cd0c4305441d426d04572d88c1 neglected to update this. Back-patch to v13, which introduced DROP DATABASE FORCE. Reviewed by Amit Kapila. Reported by Kirill Reshke. Discussion: https://postgr.es/m/20240429212756.60.nmisch@google.com
* Remove GlobalVisTestNonRemovable[Full]Horizon, not used anymoreAndres Freund2024-04-17
| | | | | | | | | GlobalVisTestNonRemovableHorizon() was only used for the implementation of snapshot_too_old, which was removed in f691f5b80a8. As using GlobalVisTestNonRemovableHorizon() is not particularly efficient, no new uses for it should be added. Therefore remove. Discussion: https://postgr.es/m/20240415185720.q4dg4dlcyvvrabz4@awork3.anarazel.de
* Revert: Implement pg_wal_replay_wait() stored procedureAlexander Korotkov2024-04-11
| | | | | | | This commit reverts 06c418e163, e37662f221, bf1e650806, 25f42429e2, ee79928441, and 74eaf66f98 per review by Heikki Linnakangas. Discussion: https://postgr.es/m/b155606b-e744-4218-bda5-29379779da1a%40iki.fi
* Combine freezing and pruning steps in VACUUMHeikki Linnakangas2024-04-03
| | | | | | | | | | | | | | | | | | | | | | | | Execute both freezing and pruning of tuples in the same heap_page_prune() function, now called heap_page_prune_and_freeze(), and emit a single WAL record containing all changes. That reduces the overall amount of WAL generated. This moves the freezing logic from vacuumlazy.c to the heap_page_prune_and_freeze() function. The main difference in the coding is that in vacuumlazy.c, we looked at the tuples after the pruning had already happened, but in heap_page_prune_and_freeze() we operate on the tuples before pruning. The heap_prepare_freeze_tuple() function is now invoked after we have determined that a tuple is not going to be pruned away. VACUUM no longer needs to loop through the items on the page after pruning. heap_page_prune_and_freeze() does all the work. It now returns the list of dead offsets, including existing LP_DEAD items, to the caller. Similarly it's now responsible for tracking 'all_visible', 'all_frozen', and 'hastup' on the caller's behalf. Author: Melanie Plageman <melanieplageman@gmail.com> Discussion: https://www.postgresql.org/message-id/20240330055710.kqg6ii2cdojsxgje@liskov
* Move WaitLSNShmemInit() to CreateOrAttachShmemStructs()Alexander Korotkov2024-04-03
| | | | | | | Thanks to Andres Freund, Thomas Munrom and David Rowley for investigating this issue. Discussion: https://postgr.es/m/CAPpHfdvap5mMLikt8CUjA0osAvCJHT0qnYeR3f84EJ_Kvse0mg%40mail.gmail.com
* Implement pg_wal_replay_wait() stored procedureAlexander Korotkov2024-04-02
| | | | | | | | | | | | | | | | | | | | | | | | pg_wal_replay_wait() is to be used on standby and specifies waiting for the specific WAL location to be replayed before starting the transaction. This option is useful when the user makes some data changes on primary and needs a guarantee to see these changes on standby. The queue of waiters is stored in the shared memory array sorted by LSN. During replay of WAL waiters whose LSNs are already replayed are deleted from the shared memory array and woken up by setting of their latches. pg_wal_replay_wait() 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 it is only possible to implement pg_wal_replay_wait() as a procedure working in a non-atomic context, not a function. Catversion is bumped. Discussion: https://postgr.es/m/eb12f9b03851bb2583adab5df9579b4b%40postgrespro.ru Author: Kartyshov Ivan, Alexander Korotkov Reviewed-by: Michael Paquier, Peter Eisentraut, Dilip Kumar, Amit Kapila Reviewed-by: Alexander Lakhin, Bharath Rupireddy, Euler Taveira
* Fix false reports in pg_visibilityAlexander Korotkov2024-03-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, pg_visibility computes its xid horizon using the GetOldestNonRemovableTransactionId(). The problem is that this horizon can sometimes go backward. That can lead to reporting false errors. In order to fix that, this commit implements a new function GetStrictOldestNonRemovableTransactionId(). This function computes the xid horizon, which would be guaranteed to be newer or equal to any xid horizon computed before. We have to do the following to achieve this. 1. Ignore processes xmin's, because they consider connection to other databases that were ignored before. 2. Ignore KnownAssignedXids, because they are not database-aware. At the same time, the primary could compute its horizons database-aware. 3. Ignore walsender xmin, because it could go backward if some replication connections don't use replication slots. As a result, we're using only currently running xids to compute the horizon. Surely these would significantly sacrifice accuracy. But we have to do so to avoid reporting false errors. Inspired by earlier patch by Daniel Shelepanov and the following discussion with Robert Haas and Tom Lane. Discussion: https://postgr.es/m/1649062270.289865713%40f403.i.mail.ru Reviewed-by: Alexander Lakhin, Dmitry Koval
* Make the order of the header file includes consistentPeter Eisentraut2024-03-13
| | | | | | | | Similar to commit 7e735035f20. Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAMbWs4-WhpCFMbXCjtJ%2BFzmjfPrp7Hw1pk4p%2BZpU95Kh3ofZ1A%40mail.gmail.com
* Remove the adminpack contrib extensionDaniel Gustafsson2024-03-04
| | | | | | | | | | | | The adminpack extension was only used to support pgAdmin III, which in turn was declared EOL many years ago. Removing the extension also allows us to remove functions from core as well which were only used to support old version of adminpack. Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Reviewed-by: Nathan Bossart <nathandbossart@gmail.com> Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Discussion: https://postgr.es/m/CALj2ACUmL5TraYBUBqDZBi1C+Re8_=SekqGYqYprj_W8wygQ8w@mail.gmail.com
* Remove unused #include's from backend .c filesPeter Eisentraut2024-03-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | as determined by include-what-you-use (IWYU) While IWYU also suggests to *add* a bunch of #include's (which is its main purpose), this patch does not do that. In some cases, a more specific #include replaces another less specific one. Some manual adjustments of the automatic result: - IWYU currently doesn't know about includes that provide global variable declarations (like -Wmissing-variable-declarations), so those includes are being kept manually. - All includes for port(ability) headers are being kept for now, to play it safe. - No changes of catalog/pg_foo.h to catalog/pg_foo_d.h, to keep the patch from exploding in size. Note that this patch touches just *.c files, so nothing declared in header files changes in hidden ways. As a small example, in src/backend/access/transam/rmgr.c, some IWYU pragma annotations are added to handle a special case there. Discussion: https://www.postgresql.org/message-id/flat/af837490-6b2f-46df-ba05-37ea6a6653fc%40eisentraut.org
* Use MyBackendType in more places to check what process this isHeikki Linnakangas2024-03-04
| | | | | | | | | | Remove IsBackgroundWorker, IsAutoVacuumLauncherProcess(), IsAutoVacuumWorkerProcess(), and IsLogicalSlotSyncWorker() in favor of new Am*Process() macros that use MyBackendType. For consistency with the existing Am*Process() macros. Reviewed-by: Andres Freund Discussion: https://www.postgresql.org/message-id/f3ecd4cb-85ee-4e54-8278-5fabfb3a4ed0@iki.fi
* Replace BackendIds with 0-based ProcNumbersHeikki Linnakangas2024-03-03
| | | | | | | | | | | | | | | | | | Now that BackendId was just another index into the proc array, it was redundant with the 0-based proc numbers used in other places. Replace all usage of backend IDs with proc numbers. The only place where the term "backend id" remains is in a few pgstat functions that expose backend IDs at the SQL level. Those IDs are now in fact 0-based ProcNumbers too, but the documentation still calls them "backend ids". That term still seems appropriate to describe what the numbers are, so I let it be. One user-visible effect is that pg_temp_0 is now a valid temp schema name, for backend with ProcNumber 0. Reviewed-by: Andres Freund Discussion: https://www.postgresql.org/message-id/8171f1aa-496f-46a6-afc3-c46fe7a9b407@iki.fi
* Redefine backend ID to be an index into the proc arrayHeikki Linnakangas2024-03-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously, backend ID was an index into the ProcState array, in the shared cache invalidation manager (sinvaladt.c). The entry in the ProcState array was reserved at backend startup by scanning the array for a free entry, and that was also when the backend got its backend ID. Things become slightly simpler if we redefine backend ID to be the index into the PGPROC array, and directly use it also as an index to the ProcState array. This uses a little more memory, as we reserve a few extra slots in the ProcState array for aux processes that don't need them, but the simplicity is worth it. Aux processes now also have a backend ID. This simplifies the reservation of BackendStatusArray and ProcSignal slots. You can now convert a backend ID into an index into the PGPROC array simply by subtracting 1. We still use 0-based "pgprocnos" in various places, for indexes into the PGPROC array, but the only difference now is that backend IDs start at 1 while pgprocnos start at 0. (The next commmit will get rid of the term "backend ID" altogether and make everything 0-based.) There is still a 'backendId' field in PGPROC, now part of 'vxid' which encapsulates the backend ID and local transaction ID together. It's needed for prepared xacts. For regular backends, the backendId is always equal to pgprocno + 1, but for prepared xact PGPROC entries, it's the ID of the original backend that processed the transaction. Reviewed-by: Andres Freund, Reid Thompson Discussion: https://www.postgresql.org/message-id/8171f1aa-496f-46a6-afc3-c46fe7a9b407@iki.fi
* Add helper functions for dshash tables with string keys.Nathan Bossart2024-02-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Presently, string keys are not well-supported for dshash tables. The dshash code always copies key_size bytes into new entries' keys, and dshash.h only provides compare and hash functions that forward to memcmp() and tag_hash(), both of which do not stop at the first NUL. This means that callers must pad string keys so that the data beyond the first NUL does not adversely affect the results of copying, comparing, and hashing the keys. To better support string keys in dshash tables, this commit does a couple things: * A new copy_function field is added to the dshash_parameters struct. This function pointer specifies how the key should be copied into new table entries. For example, we only want to copy up to the first NUL byte for string keys. A dshash_memcpy() helper function is provided and used for all existing in-tree dshash tables without string keys. * A set of helper functions for string keys are provided. These helper functions forward to strcmp(), strcpy(), and string_hash(), all of which ignore data beyond the first NUL. This commit also adjusts the DSM registry's dshash table to use the new helper functions for string keys. Reviewed-by: Andy Fan Discussion: https://postgr.es/m/20240119215941.GA1322079%40nathanxps13
* Remove superfluous 'pgprocno' field from PGPROCHeikki Linnakangas2024-02-22
| | | | | | | | | It was always just the index of the PGPROC entry from the beginning of the proc array. Introduce a macro to compute it from the pointer instead. Reviewed-by: Andres Freund Discussion: https://www.postgresql.org/message-id/8171f1aa-496f-46a6-afc3-c46fe7a9b407@iki.fi
* Centralize logic for restoring errno in signal handlers.Nathan Bossart2024-02-14
| | | | | | | | | | | | | | | | Presently, we rely on each individual signal handler to save the initial value of errno and then restore it before returning if needed. This is easily forgotten and, if missed, often goes undetected for a long time. In commit 3b00fdba9f, we introduced a wrapper signal handler function that checks whether MyProcPid matches getpid(). This commit moves the aforementioned errno restoration code from the individual signal handlers to the new wrapper handler so that we no longer need to worry about missing it. Reviewed-by: Andres Freund, Noah Misch Discussion: https://postgr.es/m/20231121212008.GA3742740%40nathanxps13
* Add a slot synchronization function.Amit Kapila2024-02-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit introduces a new SQL function pg_sync_replication_slots() which is used to synchronize the logical replication slots from the primary server to the physical standby so that logical replication can be resumed after a failover or planned switchover. A new 'synced' flag is introduced in pg_replication_slots view, indicating whether the slot has been synchronized from the primary server. On a standby, synced slots cannot be dropped or consumed, and any attempt to perform logical decoding on them will result in an error. The logical replication slots on the primary can be synchronized to the hot standby by using the 'failover' parameter of pg-create-logical-replication-slot(), or by using the 'failover' option of CREATE SUBSCRIPTION during slot creation, and then calling pg_sync_replication_slots() on standby. For the synchronization to work, it is mandatory to have a physical replication slot between the primary and the standby aka 'primary_slot_name' should be configured on the standby, and 'hot_standby_feedback' must be enabled on the standby. It is also necessary to specify a valid 'dbname' in the 'primary_conninfo'. If a logical slot is invalidated on the primary, then that slot on the standby is also invalidated. If a logical slot on the primary is valid but is invalidated on the standby, then that slot is dropped but will be recreated on the standby in the next pg_sync_replication_slots() call provided the slot still exists on the primary server. It is okay to recreate such slots as long as these are not consumable on standby (which is the case currently). This situation may occur due to the following reasons: - The 'max_slot_wal_keep_size' on the standby is insufficient to retain WAL records from the restart_lsn of the slot. - 'primary_slot_name' is temporarily reset to null and the physical slot is removed. The slot synchronization status on the standby can be monitored using the 'synced' column of pg_replication_slots view. A functionality to automatically synchronize slots by a background worker and allow logical walsenders to wait for the physical will be done in subsequent commits. Author: Hou Zhijie, Shveta Malik, Ajin Cherian based on an earlier version by Peter Eisentraut Reviewed-by: Masahiko Sawada, Bertrand Drouvot, Peter Smith, Dilip Kumar, Nisha Moond, Kuroda Hayato, Amit Kapila Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
* Fix 'mmap' DSM implementation with allocations larger than 4 GBHeikki Linnakangas2024-02-13
| | | | | | Fixes bug #18341. Backpatch to all supported versions. Discussion: https://www.postgresql.org/message-id/18341-ce16599e7fd6228c@postgresql.org
* Fix possible NULL pointer dereference in GetNamedDSMSegment().Nathan Bossart2024-01-22
| | | | | | | | | | | | GetNamedDSMSegment() doesn't check whether dsm_attach() returns NULL, which creates the possibility of a NULL pointer dereference soon after. To fix, emit an ERROR if dsm_attach() returns NULL. This shouldn't happen, but it would be nice to avoid a segfault if it does. In passing, tidy up the surrounding code. Reported-by: Tom Lane Reviewed-by: Michael Paquier, Bharath Rupireddy Discussion: https://postgr.es/m/3348869.1705854106%40sss.pgh.pa.us
* Add backend support for injection pointsMichael Paquier2024-01-22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Injection points are a new facility that makes possible for developers to run custom code in pre-defined code paths. Its goal is to provide ways to design and run advanced tests, for cases like: - Race conditions, where processes need to do actions in a controlled ordered manner. - Forcing a state, like an ERROR, FATAL or even PANIC for OOM, to force recovery, etc. - Arbitrary sleeps. This implements some basics, and there are plans to extend it more in the future depending on what's required. Hence, this commit adds a set of routines in the backend that allows developers to attach, detach and run injection points: - A code path calling an injection point can be declared with the macro INJECTION_POINT(name). - InjectionPointAttach() and InjectionPointDetach() to respectively attach and detach a callback to/from an injection point. An injection point name is registered in a shmem hash table with a library name and a function name, which will be used to load the callback attached to an injection point when its code path is run. Injection point names are just strings, so as an injection point can be declared and run by out-of-core extensions and modules, with callbacks defined in external libraries. This facility is hidden behind a dedicated switch for ./configure and meson, disabled by default. Note that backends use a local cache to store callbacks already loaded, cleaning up their cache if a callback has found to be removed on a best-effort basis. This could be refined further but any tests but what we have here was fine with the tests I've written while implementing these backend APIs. Author: Michael Paquier, with doc suggestions from Ashutosh Bapat. Reviewed-by: Ashutosh Bapat, Nathan Bossart, Álvaro Herrera, Dilip Kumar, Amul Sul, Nazir Bilal Yavuz Discussion: https://postgr.es/m/ZTiV8tn_MIb_H2rE@paquier.xyz
* Introduce the dynamic shared memory registry.Nathan Bossart2024-01-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | Presently, the most straightforward way for a shared library to use shared memory is to request it at server startup via a shmem_request_hook, which requires specifying the library in shared_preload_libraries. Alternatively, the library can create a dynamic shared memory (DSM) segment, but absent a shared location to store the segment's handle, other backends cannot use it. This commit introduces a registry for DSM segments so that these other backends can look up existing segments with a library-specified string. This allows libraries to easily use shared memory without needing to request it at server startup. The registry is accessed via the new GetNamedDSMSegment() function. This function handles allocating the segment and initializing it via a provided callback. If another backend already created and initialized the segment, it simply attaches the segment. GetNamedDSMSegment() locks the registry appropriately to ensure that only one backend initializes the segment and that all other backends just attach it. The registry itself is comprised of a dshash table that stores the DSM segment handles keyed by a library-specified string. Reviewed-by: Michael Paquier, Andrei Lepikhov, Nikita Malakhov, Robert Haas, Bharath Rupireddy, Zhang Mingli, Amul Sul Discussion: https://postgr.es/m/20231205034647.GA2705267%40nathanxps13
* Fix name collision in c64086b79dbaAlexander Korotkov2024-01-19
| | | | | Reported-by: Erik Rijkers, Tom Lane Discussion: https://postgr.es/m/E1rQqeS-002A0s-Qm%40gemulon.postgresql.org
* Reorder actions in ProcArrayApplyRecoveryInfo()Alexander Korotkov2024-01-19
| | | | | | | | | | | | | | Since 5a1dfde8334b, 2PC filenames use FullTransactionId. Thus, it needs to convert TransactionId to FullTransactionId in StandbyTransactionIdIsPrepared() using TransamVariables->nextXid. However, ProcArrayApplyRecoveryInfo() first releases locks with usage StandbyTransactionIdIsPrepared(), then advances TransamVariables->nextXid. This sequence of actions could cause errors. This commit makes ProcArrayApplyRecoveryInfo() advance TransamVariables->nextXid before releasing locks. Reported-by: Thomas Munro, Michael Paquier Discussion: https://postgr.es/m/CA%2BhUKGLj_ve1_pNAnxwYU9rDcv7GOhsYXJt7jMKSA%3D5-6ss-Cw%40mail.gmail.com Discussion: https://postgr.es/m/Zadp9f4E1MYvMJqe%40paquier.xyz
* Update copyright for 2024Bruce Momjian2024-01-03
| | | | | | | | Reported-by: Michael Paquier Discussion: https://postgr.es/m/ZZKTDPxBBMt3C0J9@paquier.xyz Backpatch-through: 12
* Add support for incremental backup.Robert Haas2023-12-20
| | | | | | | | | | | | | | | | | | | | | | To take an incremental backup, you use the new replication command UPLOAD_MANIFEST to upload the manifest for the prior backup. This prior backup could either be a full backup or another incremental backup. You then use BASE_BACKUP with the INCREMENTAL option to take the backup. pg_basebackup now has an --incremental=PATH_TO_MANIFEST option to trigger this behavior. An incremental backup is like a regular full backup except that some relation files are replaced with files with names like INCREMENTAL.${ORIGINAL_NAME}, and the backup_label file contains additional lines identifying it as an incremental backup. The new pg_combinebackup tool can be used to reconstruct a data directory from a full backup and a series of incremental backups. Patch by me. Reviewed by Matthias van de Meent, Dilip Kumar, Jakub Wartak, Peter Eisentraut, and Álvaro Herrera. Thanks especially to Jakub for incredibly helpful and extensive testing. Discussion: http://postgr.es/m/CA+TgmoYOYZfMCyOXFyC-P+-mdrZqm5pP2N7S-r0z3_402h9rsA@mail.gmail.com
* Remove trace_recovery_messagesMichael Paquier2023-12-11
| | | | | | | | | | | | This GUC was intended as a debugging help in the 9.0 area when hot standby and streaming replication were being developped, able to offer more information at LOG level rather than DEBUGn. There are more tools available these days that are able to offer rather equivalent information, like pg_waldump introduced in 9.3. It is not obvious how this facility is useful these days, so let's remove it. Author: Bharath Rupireddy Discussion: https://postgr.es/m/ZXEXEAUVFrvpquSd@paquier.xyz
* Rename ShmemVariableCache to TransamVariablesHeikki Linnakangas2023-12-08
| | | | | | | | The old name was misleading: It's not a cache, the values kept in the struct are the authoritative source. Reviewed-by: Tristan Partin, Richard Guo Discussion: https://www.postgresql.org/message-id/6537d63d-4bb5-46f8-9b5d-73a8ba4720ab@iki.fi
* Initialize ShmemVariableCache like other shmem areasHeikki Linnakangas2023-12-08
| | | | | | | For sake of consistency. Reviewed-by: Tristan Partin, Richard Guo Discussion: https://www.postgresql.org/message-id/6537d63d-4bb5-46f8-9b5d-73a8ba4720ab@iki.fi
* Refactor CreateSharedMemoryAndSemaphoresHeikki Linnakangas2023-12-03
| | | | | | | | | | | | For clarity, have separate functions for *creating* the shared memory and semaphores at postmaster or single-user backend startup, and for *attaching* to existing shared memory structures in EXEC_BACKEND case. CreateSharedMemoryAndSemaphores() is now called only at postmaster startup, and a new AttachSharedMemoryStructs() function is called at backend startup in EXEC_BACKEND mode. Reviewed-by: Tristan Partin, Andres Freund Discussion: https://www.postgresql.org/message-id/7a59b073-5b5b-151e-7ed3-8b01ff7ce9ef@iki.fi
* Use ResourceOwner to track WaitEventSets.Heikki Linnakangas2023-11-23
| | | | | | | | | | | | | | | | | | | | | | | A WaitEventSet holds file descriptors or event handles (on Windows). If FreeWaitEventSet is not called, those fds or handles are leaked. Use ResourceOwners to track WaitEventSets, to clean those up automatically on error. This was a live bug in async Append nodes, if a FDW's ForeignAsyncRequest function failed. (In back branches, I will apply a more localized fix for that based on PG_TRY-PG_FINALLY.) The added test doesn't check for leaking resources, so it passed even before this commit. But at least it covers the code path. In the passing, fix misleading comment on what the 'nevents' argument to WaitEventSetWait means. Report by Alexander Lakhin, analysis and suggestion for the fix by Tom Lane. Fixes bug #17828. Reviewed-by: Alexander Lakhin, Thomas Munro Discussion: https://www.postgresql.org/message-id/472235.1678387869@sss.pgh.pa.us