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* Mark misc static global variables as constHeikki Linnakangas2024-08-06
| | | | | Reviewed-by: Andres Freund Discussion: https://www.postgresql.org/message-id/54c29fb0-edf2-48ea-9814-44e918bbd6e8@iki.fi
* Allow parallel workers to cope with a newly-created session user ID.Tom Lane2024-08-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Parallel workers failed after a sequence like BEGIN; CREATE USER foo; SET SESSION AUTHORIZATION foo; because check_session_authorization could not see the uncommitted pg_authid row for "foo". This is because we ran RestoreGUCState() in a separate transaction using an ordinary just-created snapshot. The same disease afflicts any other GUC that requires catalog lookups and isn't forgiving about the lookups failing. To fix, postpone RestoreGUCState() into the worker's main transaction after we've set up a snapshot duplicating the leader's. This affects check_transaction_isolation and check_transaction_deferrable, which think they should only run during transaction start. Make them act like check_transaction_read_only, which already knows it should silently accept the value when InitializingParallelWorker. This un-reverts commit f5f30c22e. The original plan was to back-patch that, but the fact that 0ae5b763e proved to be a pre-requisite shows that the subtle API change for GUC hooks might actually break some of them. The problem we're trying to fix seems not worth taking such a risk for in stable branches. Per bug #18545 from Andrey Rachitskiy. Discussion: https://postgr.es/m/18545-feba138862f19aaa@postgresql.org
* Clean up handling of client_encoding GUC in parallel workers.Tom Lane2024-08-06
| | | | | | | | | | | | | | | | | | | | | | | The previous coding here threw an error from assign_client_encoding if it was invoked in a parallel worker. That's a very fundamental violation of the GUC hook API: assign hooks must not throw errors. The place to complain is in the check hook, so move the test to there, and use the regular check-hook API (ie return false) to report it. The reason this coding is a problem is that it breaks GUC rollback, which may occur after we leave InitializingParallelWorker state. That case seems not actually reachable before now, but commit f5f30c22e made it reachable, so we need to fix this before that can be un-reverted. In passing, improve the commentary in ParallelWorkerMain, and add a check for failure of SetClientEncoding. That's another case that can't happen now but might become possible after foreseeable code rearrangements (notably, if the shortcut of skipping PrepareClientEncoding stops being OK). Discussion: https://postgr.es/m/18545-feba138862f19aaa@postgresql.org
* 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
* Add redo LSN to pgstats filesMichael Paquier2024-08-02
| | | | | | | | | | | | | | | | This is used in the startup process to check that the pgstats file we are reading includes the redo LSN referring to the shutdown checkpoint where it has been written. The redo LSN in the pgstats file needs to match with what the control file has. This is intended to be used for an upcoming change that will extend the write of the stats file to happen during checkpoints, rather than only shutdown sequences. Bump PGSTAT_FILE_FORMAT_ID. Reviewed-by: Bertrand Drouvot Discussion: https://postgr.es/m/Zp8o6_cl0KSgsnvS@paquier.xyz
* Revert "Allow parallel workers to cope with a newly-created session user ID."Tom Lane2024-07-31
| | | | | | | | | | | | | | | | This reverts commit f5f30c22ed69fb37b896c4d4546b2ab823c3fd61. Some buildfarm animals are failing with "cannot change "client_encoding" during a parallel operation". It looks like assign_client_encoding is unhappy at being asked to roll back a client_encoding setting after a parallel worker encounters a failure. There must be more to it though: why didn't I see this during local testing? In any case, it's clear that moving the RestoreGUCState() call is not as side-effect-free as I thought. Given that the bug f5f30c22e intended to fix has gone unreported for years, it's not something that's urgent to fix; I'm not willing to risk messing with it further with only days to our next release wrap.
* Allow parallel workers to cope with a newly-created session user ID.Tom Lane2024-07-31
| | | | | | | | | | | | | | | | | | | | | | | | Parallel workers failed after a sequence like BEGIN; CREATE USER foo; SET SESSION AUTHORIZATION foo; because check_session_authorization could not see the uncommitted pg_authid row for "foo". This is because we ran RestoreGUCState() in a separate transaction using an ordinary just-created snapshot. The same disease afflicts any other GUC that requires catalog lookups and isn't forgiving about the lookups failing. To fix, postpone RestoreGUCState() into the worker's main transaction after we've set up a snapshot duplicating the leader's. This affects check_transaction_isolation and check_transaction_deferrable, which think they should only run during transaction start. Make them act like check_transaction_read_only, which already knows it should silently accept the value when InitializingParallelWorker. Per bug #18545 from Andrey Rachitskiy. Back-patch to all supported branches, because this has been wrong for awhile. Discussion: https://postgr.es/m/18545-feba138862f19aaa@postgresql.org
* Replace static buf with a stack-allocated one in ReadControlFileHeikki Linnakangas2024-07-30
| | | | | | | It's only used very locally within the function. Reviewed-by: Robert Haas Discussion: https://www.postgresql.org/message-id/7f86e06a-98c5-4ce3-8ec9-3885c8de0358@iki.fi
* Replace static buf with palloc in str_time()Heikki Linnakangas2024-07-30
| | | | | | | | | | The function is used only once in the startup process, so the leak into current memory context is harmless. This is a tiny step in making the server thread-safe. Reviewed-by: Robert Haas Discussion: https://www.postgresql.org/message-id/7f86e06a-98c5-4ce3-8ec9-3885c8de0358@iki.fi
* Fix more holes with SLRU code in need of int64 for segment numbersMichael Paquier2024-07-27
| | | | | | | | | | This is a continuation of 3937cadfd438, taking care of more areas I have managed to miss previously. Reported-by: Noah Misch Reviewed-by: Noah Misch Discussion: https://postgr.es/m/20240724130059.1f.nmisch@google.com Backpatch-through: 17
* Wait for WAL summarization to catch up before creating .partial file.Robert Haas2024-07-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a standby is promoted, CleanupAfterArchiveRecovery() may decide to rename the final WAL file from the old timeline by adding ".partial" to the name. If WAL summarization is enabled and this file is renamed before its partial contents are summarized, WAL summarization breaks: the summarizer gets stuck at that point in the WAL stream and just errors out. To fix that, first make the startup process wait for WAL summarization to catch up before renaming the file. Generally, this should be quick, and if it's not, the user can shut off summarize_wal and try again. To make this fix work, also teach the WAL summarizer that after a promotion has occurred, no more WAL can appear on the previous timeline: previously, the WAL summarizer wouldn't switch to the new timeline until we actually started writing WAL there, but that meant that when the startup process was waiting for the WAL summarizer, it was waiting for an action that the summarizer wasn't yet prepared to take. In the process of fixing these bugs, I realized that the logic to wait for WAL summarization to catch up was spread out in a way that made it difficult to reuse properly, so this code refactors things to make it easier. Finally, add a test case that would have caught this bug and the previously-fixed bug that WAL summarization sometimes needs to back up when the timeline changes. Discussion: https://postgr.es/m/CA+TgmoZGEsZodXC4f=XZNkAeyuDmWTSkpkjCEOcF19Am0mt_OA@mail.gmail.com
* Allow altering of two_phase option of a SUBSCRIPTION.Amit Kapila2024-07-24
| | | | | | | | | | | | | | | | | | | | The two_phase option is controlled by both the publisher (as a slot option) and the subscriber (as a subscription option), so the slot option must also be modified. Changing the 'two_phase' option for a subscription from 'true' to 'false' is permitted only when there are no pending prepared transactions corresponding to that subscription. Otherwise, the changes of already prepared transactions can be replicated again along with their corresponding commit leading to duplicate data or errors. To avoid data loss, the 'two_phase' option for a subscription can only be changed from 'false' to 'true' once the initial data synchronization is completed. Therefore this is performed later by the logical replication worker. Author: Hayato Kuroda, Ajin Cherian, Amit Kapila Reviewed-by: Peter Smith, Hou Zhijie, Amit Kapila, Vitaly Davydov, Vignesh C Discussion: https://postgr.es/m/8fab8-65d74c80-1-2f28e880@39088166
* Use more consistently int64 for page numbers in SLRU-related codeMichael Paquier2024-07-23
| | | | | | | | | | | | | | clog.c, async.c and predicate.c included some SLRU page numbers still handled as 4-byte integers, while int64 should be used for this purpose. These holes have been introduced in 4ed8f0913bfd, that has introduced the use of 8-byte integers for SLRU page numbers, still forgot about the code paths updated by this commit. Reported-by: Noah Misch Author: Aleksander Alekseev, Michael Paquier Discussion: https://postgr.es/m/20240626002747.dc.nmisch@google.com Backpatch-through: 17
* Get rid of a global variablePeter Eisentraut2024-07-23
| | | | | | | | bootstrap_data_checksum_version can just as easily be passed to where it is used via function arguments. Reviewed-by: Andres Freund <andres@anarazel.de> Discussion: https://www.postgresql.org/message-id/flat/e0a62134-83da-4ba4-8cdb-ceb0111c95ce@eisentraut.org
* Improve comments in slru.{c,h} about segment name formatMichael Paquier2024-07-23
| | | | | | | | | | | | slru.h described incorrectly how SLRU segment names are formatted depending on the segment number and if long or short segment names are used. This commit closes the gap with a better description, fitting with the reality. Reported-by: Noah Misch Author: Aleksander Alekseev Discussion: https://postgr.es/m/20240626002747.dc.nmisch@google.com Backpatch-through: 17
* Initialize wal_level in the initial checkpoint record.Robert Haas2024-07-22
| | | | | | As per Coverity and Tom Lane, commit 402b586d0 (back-patched to v17 as 2b5819e2b) forgot to initialize this new structure member in this code path.
* Do not summarize WAL if generated with wal_level=minimal.Robert Haas2024-07-18
| | | | | | | | | | | | | | | | | | | | | | | | | | To do this, we must include the wal_level in the first WAL record covered by each summary file; so add wal_level to struct Checkpoint and the payload of XLOG_CHECKPOINT_REDO and XLOG_END_OF_RECOVERY. This, in turn, requires bumping XLOG_PAGE_MAGIC and, since the Checkpoint is also stored in the control file, also PG_CONTROL_VERSION. It's not great to do that so late in the release cycle, but the alternative seems to ship v17 without robust protections against this scenario, which could result in corrupted incremental backups. A side effect of this patch is that, when a server with wal_level=replica is started with summarize_wal=on for the first time, summarization will no longer begin with the oldest WAL that still exists in pg_wal, but rather from the first checkpoint after that. This change should be harmless, because a WAL summary for a partial checkpoint cycle can never make an incremental backup possible when it would otherwise not have been. Report by Fujii Masao. Patch by me. Review and/or testing by Jakub Wartak and Fujii Masao. Discussion: http://postgr.es/m/6e30082e-041b-4e31-9633-95a66de76f5d@oss.nttdata.com
* Assign error codes where missing for user-facing failuresMichael Paquier2024-07-04
| | | | | | | | | | | | | | | | | | All the errors triggered in the code paths patched here would cause the backend to issue an internal_error errcode, which is a state that should be used only for "can't happen" situations. However, these code paths are reachable by the regression tests, and could be seen by users in valid cases. Some regression tests expect internal errcodes as they manipulate the backend state to cause corruption (like checksums), or use elog() because it is more convenient (like injection points), these have no need to change. This reduces the number of internal failures triggered in a check-world by more than half, while providing correct errcodes for these valid cases. Reviewed-by: Robert Haas Discussion: https://postgr.es/m/Zic_GNgos5sMxKoa@paquier.xyz
* Use safe string copy routineDaniel Gustafsson2024-07-02
| | | | | | | | | | | Using memcpy with strlen as the size parameter will not take the NULL terminator into account, relying instead on the destination buffer being properly initialized. Replace with strlcpy which is a safer alternative, and more in line with how we handle copying strings elsewhere. Author: Ranier Vilela <ranier.vf@gmail.com> Discussion: https://postgr.es/m/CAEudQApAsbLsQ+gGiw-hT+JwGhgogFa_=5NUkgFO6kOPxyNidQ@mail.gmail.com
* Preserve CurrentMemoryContext across Start/CommitTransactionCommand.Tom Lane2024-07-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Up to now, committing a transaction has caused CurrentMemoryContext to get set to TopMemoryContext. Most callers did not pay any particular heed to this, which is problematic because TopMemoryContext is a long-lived context that never gets reset. If the caller assumes it can leak memory because it's running in a limited-lifespan context, that behavior translates into a session-lifespan memory leak. The first-reported instance of this involved ProcessIncomingNotify, which is called from the main processing loop that normally runs in MessageContext. That outer-loop code assumes that whatever it allocates will be cleaned up when we're done processing the current client message --- but if we service a notify interrupt, then whatever gets allocated before the next switch to MessageContext will be permanently leaked in TopMemoryContext. sinval catchup interrupts have a similar problem, and I strongly suspect that some places in logical replication do too. To fix this in a generic way, let's redefine the behavior as "CommitTransactionCommand restores the memory context that was current at entry to StartTransactionCommand". This clearly fixes the issue for the notify and sinval cases, and it seems to match the mental model that's in use in the logical replication code, to the extent that anybody thought about it there at all. For consistency, likewise make subtransaction exit restore the context that was current at subtransaction start (rather than always selecting the CurTransactionContext of the parent transaction level). This case has less risk of resulting in a permanent leak than the outer-level behavior has, but it would not meet the principle of least surprise for some CommitTransactionCommand calls to restore the previous context while others don't. While we're here, also change xact.c so that we reset TopTransactionContext at transaction exit and then re-use it in later transactions, rather than dropping and recreating it in each cycle. This probably doesn't save a lot given the context recycling mechanism in aset.c, but it should save a little bit. Per suggestion from David Rowley. (Parenthetically, the text in src/backend/utils/mmgr/README implies that this is how I'd planned to implement it as far back as commit 1aebc3618 --- but the code actually added in that commit just drops and recreates it each time.) This commit also cleans up a few places outside xact.c that were needlessly making TopMemoryContext current, and thus risking more leaks of the same kind. I don't think any of them represent significant leak risks today, but let's deal with them while the issue is top-of-mind. Per bug #18512 from wizardbrony. Commit to HEAD only, as this change seems to have some risk of breaking things for some callers. We'll apply a narrower fix for the known-broken cases in the back branches. Discussion: https://postgr.es/m/3478884.1718656625@sss.pgh.pa.us
* Prevent summarizer hang when summarize_wal turned off and back on.Robert Haas2024-06-28
| | | | | | | | | | | | | | | Before this commit, when the WAL summarizer started up or recovered from an error, it would resume summarization from wherever it left off. That was OK normally, but wrong if summarize_wal=off had been turned off temporary, allowing some WAL to be removed, and then turned back on again. In such cases, the WAL summarizer would simply hang forever. This commit changes the reinitialization sequence for WAL summarizer to rederive the starting position in the way we were already doing at initial startup, fixing the problem. Per report from Israel Barth Rubio. Reviewed by Tom Lane. Discussion: http://postgr.es/m/CA+TgmoYN6x=YS+FoFOS6=nr6=qkXZFWhdiL7k0oatGwug2hcuA@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 bugs in MultiXact truncationHeikki Linnakangas2024-06-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1. TruncateMultiXact() performs the SLRU truncations in a critical section. Deleting the SLRU segments calls ForwardSyncRequest(), which will try to compact the request queue if it's full (CompactCheckpointerRequestQueue()). That in turn allocates memory, which is not allowed in a critical section. Backtrace: TRAP: failed Assert("CritSectionCount == 0 || (context)->allowInCritSection"), File: "../src/backend/utils/mmgr/mcxt.c", Line: 1353, PID: 920981 postgres: autovacuum worker template0(ExceptionalCondition+0x6e)[0x560a501e866e] postgres: autovacuum worker template0(+0x5dce3d)[0x560a50217e3d] postgres: autovacuum worker template0(ForwardSyncRequest+0x8e)[0x560a4ffec95e] postgres: autovacuum worker template0(RegisterSyncRequest+0x2b)[0x560a50091eeb] postgres: autovacuum worker template0(+0x187b0a)[0x560a4fdc2b0a] postgres: autovacuum worker template0(SlruDeleteSegment+0x101)[0x560a4fdc2ab1] postgres: autovacuum worker template0(TruncateMultiXact+0x2fb)[0x560a4fdbde1b] postgres: autovacuum worker template0(vac_update_datfrozenxid+0x4b3)[0x560a4febd2f3] postgres: autovacuum worker template0(+0x3adf66)[0x560a4ffe8f66] postgres: autovacuum worker template0(AutoVacWorkerMain+0x3ed)[0x560a4ffe7c2d] postgres: autovacuum worker template0(+0x3b1ead)[0x560a4ffecead] postgres: autovacuum worker template0(+0x3b620e)[0x560a4fff120e] postgres: autovacuum worker template0(+0x3b3fbb)[0x560a4ffeefbb] postgres: autovacuum worker template0(+0x2f724e)[0x560a4ff3224e] /lib/x86_64-linux-gnu/libc.so.6(+0x27c8a)[0x7f62cc642c8a] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x85)[0x7f62cc642d45] postgres: autovacuum worker template0(_start+0x21)[0x560a4fd16f31] To fix, bail out in CompactCheckpointerRequestQueue() without doing anything, if it's called in a critical section. That covers the above call path, as well as any other similar cases where RegisterSyncRequest might be called in a critical section. 2. After fixing that, another problem became apparent: Autovacuum process doing that truncation can deadlock with the checkpointer process. TruncateMultiXact() sets "MyProc->delayChkptFlags |= DELAY_CHKPT_START". If the sync request queue is full and cannot be compacted, the process will repeatedly sleep and retry, until there is room in the queue. However, if the checkpointer is trying to start a checkpoint at the same time, and is waiting for the DELAY_CHKPT_START processes to finish, the queue will never shrink. More concretely, the autovacuum process is stuck here: #0 0x00007fc934926dc3 in epoll_wait () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x000056220b24348b in WaitEventSetWaitBlock (set=0x56220c2e4b50, occurred_events=0x7ffe7856d040, nevents=1, cur_timeout=<optimized out>) at ../src/backend/storage/ipc/latch.c:1570 #2 WaitEventSetWait (set=0x56220c2e4b50, timeout=timeout@entry=10, occurred_events=<optimized out>, occurred_events@entry=0x7ffe7856d040, nevents=nevents@entry=1, wait_event_info=wait_event_info@entry=150994949) at ../src/backend/storage/ipc/latch.c:1516 #3 0x000056220b243224 in WaitLatch (latch=<optimized out>, latch@entry=0x0, wakeEvents=wakeEvents@entry=40, timeout=timeout@entry=10, wait_event_info=wait_event_info@entry=150994949) at ../src/backend/storage/ipc/latch.c:538 #4 0x000056220b26cf46 in RegisterSyncRequest (ftag=ftag@entry=0x7ffe7856d0a0, type=type@entry=SYNC_FORGET_REQUEST, retryOnError=true) at ../src/backend/storage/sync/sync.c:614 #5 0x000056220af9db0a in SlruInternalDeleteSegment (ctl=ctl@entry=0x56220b7beb60 <MultiXactMemberCtlData>, segno=segno@entry=11350) at ../src/backend/access/transam/slru.c:1495 #6 0x000056220af9dab1 in SlruDeleteSegment (ctl=ctl@entry=0x56220b7beb60 <MultiXactMemberCtlData>, segno=segno@entry=11350) at ../src/backend/access/transam/slru.c:1566 #7 0x000056220af98e1b in PerformMembersTruncation (oldestOffset=<optimized out>, newOldestOffset=<optimized out>) at ../src/backend/access/transam/multixact.c:3006 #8 TruncateMultiXact (newOldestMulti=newOldestMulti@entry=3221225472, newOldestMultiDB=newOldestMultiDB@entry=4) at ../src/backend/access/transam/multixact.c:3201 #9 0x000056220b098303 in vac_truncate_clog (frozenXID=749, minMulti=<optimized out>, lastSaneFrozenXid=749, lastSaneMinMulti=3221225472) at ../src/backend/commands/vacuum.c:1917 #10 vac_update_datfrozenxid () at ../src/backend/commands/vacuum.c:1760 #11 0x000056220b1c3f76 in do_autovacuum () at ../src/backend/postmaster/autovacuum.c:2550 #12 0x000056220b1c2c3d in AutoVacWorkerMain (startup_data=<optimized out>, startup_data_len=<optimized out>) at ../src/backend/postmaster/autovacuum.c:1569 and the checkpointer is stuck here: #0 0x00007fc9348ebf93 in clock_nanosleep () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x00007fc9348fe353 in nanosleep () from /lib/x86_64-linux-gnu/libc.so.6 #2 0x000056220b40ecb4 in pg_usleep (microsec=microsec@entry=10000) at ../src/port/pgsleep.c:50 #3 0x000056220afb43c3 in CreateCheckPoint (flags=flags@entry=108) at ../src/backend/access/transam/xlog.c:7098 #4 0x000056220b1c6e86 in CheckpointerMain (startup_data=<optimized out>, startup_data_len=<optimized out>) at ../src/backend/postmaster/checkpointer.c:464 To fix, add AbsorbSyncRequests() to the loops where the checkpointer waits for DELAY_CHKPT_START or DELAY_CHKPT_COMPLETE operations to finish. Backpatch to v14. Before that, SLRU deletion didn't call RegisterSyncRequest, which avoided this failure. I'm not sure if there are other similar scenarios on older versions, but we haven't had any such reports. Discussion: https://www.postgresql.org/message-id/ccc66933-31c1-4f6a-bf4b-45fef0d4f22e@iki.fi
* Convert confusing macros in multixact.c to static inline functionsHeikki Linnakangas2024-06-16
| | | | | | | | | | | | | The macros were confused about the argument data types. All the arguments were called 'xid', and some of the macros included casts to TransactionId, even though the arguments were actually either MultiXactIds or MultiXactOffsets. It compiles to the same thing, because TransactionId, MultiXactId and MultiXactOffset are all typedefs of uint32, but it was highly misleading. Author: Maxim Orlov <orlovmg@gmail.com> Discussion: https://www.postgresql.org/message-id/CACG%3DezbLUG-OD1osAW3OchOMxZtdxHh2itYR9Zhh-a13wEBEQw%40mail.gmail.com Discussion: https://www.postgresql.org/message-id/ff143b24-a093-40da-9833-d36b83726bdf%40iki.fi
* Clamp result of MultiXactMemberFreezeThresholdHeikki Linnakangas2024-06-13
| | | | | | | | | | | | The purpose of the function is to reduce the effective autovacuum_multixact_freeze_max_age if the multixact members SLRU is approaching wraparound, to make multixid freezing more aggressive. The returned value should therefore never be greater than plain autovacuum_multixact_freeze_max_age. Reviewed-by: Robert Haas Discussion: https://www.postgresql.org/message-id/85fb354c-f89f-4d47-b3a2-3cbd461c90a3@iki.fi Backpatch-through: 12, all supported versions
* Make RelationFlushRelation() work without ResourceOwner during abortHeikki Linnakangas2024-06-06
| | | | | | | | | | | | | | | | | | | | | ReorderBufferImmediateInvalidation() executes invalidation messages in an aborted transaction. However, RelationFlushRelation sometimes required a valid resource owner, to temporarily increment the refcount of the relache entry. Commit b8bff07daa worked around that in the main subtransaction abort function, AbortSubTransaction(), but missed this similar case in ReorderBufferImmediateInvalidation(). To fix, introduce a separate function to invalidate a relcache entry. It does the same thing as RelationClearRelation(rebuild==true) does when outside a transaction, but can be called without incrementing the refcount. Add regression test. Before this fix, it failed with: ERROR: ResourceOwnerEnlarge called after release started Reported-by: Alexander Lakhin <exclusion@gmail.com> Discussion: https://www.postgresql.org/message-id/e56be7d9-14b1-664d-0bfc-00ce9772721c@gmail.com
* Revise GUC names quoting in messages againPeter Eisentraut2024-05-17
| | | | | | | | | | | | | | | After further review, we want to move in the direction of always quoting GUC names in error messages, rather than the previous (PG16) wildly mixed practice or the intermittent (mid-PG17) idea of doing this depending on how possibly confusing the GUC name is. This commit applies appropriate quotes to (almost?) all mentions of GUC names in error messages. It partially supersedes a243569bf65 and 8d9978a7176, which had moved things a bit in the opposite direction but which then were abandoned in a partial state. Author: Peter Smith <smithpb2250@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAHut%2BPv-kSN8SkxSdoHano_wPubqcg5789ejhCDZAcLFceBR-w%40mail.gmail.com
* Fix an assortment of typosDavid Rowley2024-05-04
| | | | | Author: Alexander Lakhin Discussion: https://postgr.es/m/ae9f2fcb-4b24-5bb0-4240-efbbbd944ca1@gmail.com
* Refactoring for CommitTransactionCommand()/AbortCurrentTransaction()Alexander Korotkov2024-04-18
| | | | | | | | | | | | | | | fefd9a3fed turned tail recursion of CommitTransactionCommand() and AbortCurrentTransaction() into iteration. However, it splits the handling of cases between different functions. This commit puts the handling of all the cases into AbortCurrentTransactionInternal() and CommitTransactionCommandInternal(). Now CommitTransactionCommand() and AbortCurrentTransaction() are just doing the repeated calls of internal functions. Reported-by: Andres Freund Discussion: https://postgr.es/m/20240415224834.w6piwtefskoh32mv%40awork3.anarazel.de Author: Andres Freund
* 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
* Use conditional variable to wait for next MultiXact offsetAlvaro Herrera2024-04-07
| | | | | | | | | | | | | | | In one multixact.c edge case, we need a mechanism to wait for one multixact offset to be written before being allowed to read the next one. We used to handle this case by sleeping for one millisecond and retrying, but such sleeps have been reported as problematic in production cases. We can avoid the problem by using a condition variable: readers sleep on it and then every creator of multixacts broadcasts into the CV when creation is sufficiently far along. Author: Kyotaro Horiguchi <horikyotajntt@gmail.com> Reviewed-by: Andrey Borodin <amborodin@acm.org> Discussion: https://postgr.es/m/47A598F4-B4E7-4029-8FEC-A06A6C3CB4B5@yandex-team.ru Discussion: https://postgr.es/m/20200515.090333.24867479329066911.horikyota.ntt
* Add XLogCtl->logInsertResultAlvaro Herrera2024-04-07
| | | | | | | | | | | | | | | | | | This tracks the position of WAL that's been fully copied into WAL buffers by all processes emitting WAL. (For some reason we call that "WAL insertion"). This is updated using atomic monotonic advance during WaitXLogInsertionsToFinish, which is not when the insertions actually occur, but it's the only place where we know where have all the insertions have completed. This value is useful in WALReadFromBuffers, which can verify that callers don't try to read past what has been inserted. (However, more infrastructure is needed in order to actually use WAL after the flush point, since it could be lost.) The value is also useful in WaitXLogInsertionsToFinish() itself, since we can now exit quickly when all WAL has been already inserted, without even having to take any locks.
* Call WaitLSNCleanup() in AbortTransaction()Alexander Korotkov2024-04-07
| | | | | | | | | | | Even though waiting for replay LSN happens without explicit transaction, AbortTransaction() is responsible for the cleanup of the shared memory if the error is thrown in a stored procedure. So, we need to do WaitLSNCleanup() there to clean up after some unexpected error happened while waiting for replay LSN. Discussion: https://postgr.es/m/202404051815.eri4u5q6oj26%40alvherre.pgsql Author: Alvaro Herrera
* Operate XLogCtl->log{Write,Flush}Result with atomicsAlvaro Herrera2024-04-05
| | | | | | | | | | | | | | | | | This removes the need to hold both the info_lck spinlock and WALWriteLock to update them. We use stock atomic write instead, with WALWriteLock held. Readers can use atomic read, without any locking. This allows for some code to be reordered: some places were a bit contorted to avoid repeated spinlock acquisition, but that's no longer a concern, so we can turn them to more natural coding. Some further changes are possible (maybe to performance wins), but in this commit I did rather minimal ones only, to avoid increasing the blast radius. Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Reviewed-by: Jeff Davis <pgsql@j-davis.com> Reviewed-by: Andres Freund <andres@anarazel.de> (earlier versions) Discussion: https://postgr.es/m/20200831182156.GA3983@alvherre.pgsql
* Split XLogCtl->LogwrtResult into separate struct membersAlvaro Herrera2024-04-03
| | | | | | | | | | | | | | | | | | | After this change we have XLogCtl->logWriteResult and ->logFlushResult. There's no functional change, other than the fact that the assignment from shared memory to local is no longer done via struct assignment, but instead using a macro that copies each member separately. The current representation is inconvenient going forward; notably, we would like to add a new member "Copy" (to keep track of the last position copied into WAL buffers), so the symmetry between the values in shared memory vs. those in local would be lost. This also gives us freedom to later change the concurrency model for the values in shared memory: we can make them use atomics instead of relying on the info_lck spinlock. Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Discussion: https://postgr.es/m/202404031119.cd2kugjk2vho@alvherre.pgsql
* Use the pairing heap instead of a flat array for LSN replay waitersAlexander Korotkov2024-04-03
| | | | | | | | | | | | | | 06c418e163 introduced pg_wal_replay_wait() procedure allowing to wait for the particular LSN to be replayed on standby. The waiters were stored in the flat array. Even though scanning small arrays is fast, that might be a problem at scale (a lot of waiting processes). This commit replaces the flat shared memory array with the pairing heap, which holds the waiter with the least LSN at the top. This gives us O(log N) complexity for both inserting and removing waiters. Reported-by: Alvaro Herrera Discussion: https://postgr.es/m/202404030658.hhj3vfxeyhft%40alvherre.pgsql
* Add error codes to some PANIC/FATAL errors reportsDaniel Gustafsson2024-04-03
| | | | | | | | | | | This adds errcodes to a set of PANIC and FATAL errors in xlog.c and relcache.c, which previously had no errcode at all set, in order to make fleetwide analysis of errorlogs easier. There are many more ereport/elogs left which could benefit from having an errcode but this at least makes a dent in the issue. Author: Nazir Bilal Yavuz <byavuz81@gmail.com> Discussion: https://postgr.es/m/CAN55FZ1k8LgLEqncPGmz_fWnrobV6bjABOTH4tOWta6xNcPQig@mail.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
* Allow "internal" subtransactions in parallel mode.Tom Lane2024-03-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Allow use of BeginInternalSubTransaction() in parallel mode, so long as the subtransaction doesn't attempt to acquire an XID or increment the command counter. Given those restrictions, the other parallel processes don't need to know about the subtransaction at all, so this should be safe. The benefit is that it allows subtransactions intended for error recovery, such as pl/pgsql exception blocks, to be used in PARALLEL SAFE functions. Another reason for doing this is that the API of BeginInternalSubTransaction() doesn't allow reporting failure. pl/python for one, and perhaps other PLs, copes very poorly with an error longjmp out of BeginInternalSubTransaction(). The headline feature of this patch removes the only easily-triggerable failure case within that function. There remain some resource-exhaustion and similar cases, which we now deal with by promoting them to FATAL errors, so that callers need not try to clean up. (It is likely that such errors would leave us with corrupted transaction state inside xact.c, making recovery difficult if not impossible anyway.) Although this work started because of a report of a pl/python crash, we're not going to do anything about that in the back branches. Back-patching this particular fix is obviously not very wise. While we could contemplate some narrower band-aid, pl/python is already an untrusted language, so it seems okay to classify this as a "so don't do that" case. Patch by me, per report from Hao Zhang. Thanks to Robert Haas for review. Discussion: https://postgr.es/m/CALY6Dr-2yLVeVPhNMhuBnRgOZo1UjoTETgtKBx1B2gUi8yy+3g@mail.gmail.com
* 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
* Add some checkpoint and redo LSNs to a couple of recovery errorsMichael Paquier2024-03-11
| | | | | | | | | | | | | | | | | | Two FATALs and one PANIC gain details about the LSNs they fail at: - When restoring from a backup_label, the FATAL log generated when not finding the checkpoint record now reports its LSN. - When restoring from a backup_label, the FATAL log generated when not finding the redo record referenced by a checkpoint record now shows both the redo and checkpoint record LSNs. - When not restoring from a backup_label, the PANIC error generated when not finding the checkpoint record now reports its LSN. This information is useful when debugging corruption issues, and these LSNs may not show up in the logs depending on the level of logging configured in the backend. Author: David Steele Discussion: https://postgr.es/m/0e90da89-77ca-4ccf-872c-9626d755e288@pgmasters.net
* Avoid stack overflow in ShowTransactionStateRec()Alexander Korotkov2024-03-08
| | | | | | | | | | | | | | | | | | | | | The function recurses, but didn't perform stack-depth checks. It's just a debugging aid, so instead of the usual check_stack_depth() call, stop the printing if we'd risk stack overflow. Here's an example of how to test this: (n=1000000; printf "BEGIN;"; for ((i=1;i<=$n;i++)); do printf "SAVEPOINT s$i;"; done; printf "SET log_min_messages = 'DEBUG5'; SAVEPOINT sp;") | psql >/dev/null In the passing, swap building the list of child XIDs and recursing to parent. That saves memory while recursing, reducing the risk of out of memory errors with lots of subtransactions. The saving is not very significant in practice, but this order seems more logical anyway. Report by Egor Chindyaskin and Alexander Lakhin. Discussion: https://www.postgresql.org/message-id/1672760457.940462079%40f306.i.mail.ru Author: Heikki Linnakangas Reviewed-by: Robert Haas, Andres Freund, Alexander Korotkov
* Turn tail recursion into iteration in CommitTransactionCommand()Alexander Korotkov2024-03-08
| | | | | | | | | | | | | | | Usually the compiler will optimize away the tail recursion anyway, but if it doesn't, you can drive the function into stack overflow. For example: (n=1000000; printf "BEGIN;"; for ((i=1;i<=$n;i++)); do printf "SAVEPOINT s$i;"; done; printf "ERROR; COMMIT;") | psql >/dev/null In order to get better readability and less changes to the existing code the recursion-replacing loop is implemented as a wrapper function. Report by Egor Chindyaskin and Alexander Lakhin. Discussion: https://postgr.es/m/1672760457.940462079%40f306.i.mail.ru Author: Alexander Korotkov, Heikki Linnakangas
* Fix misspelled assertionsAlvaro Herrera2024-03-05
| | | | | | | Remove an extra & operator, per Tom Lane. My bugs, introduced with commit 53c2a97a9266. Discussion: https://postgr.es/m/3885480.1709590472@sss.pgh.pa.us
* Rework redundant code in subtrans.cAlvaro Herrera2024-03-05
| | | | | | | | | When this code was written the duplicity didn't matter, but with all the SLRU-bank stuff we just added, it has become excessive. Turn it into a simpler loop with no code duplication. Also add a test so that this code becomes covered. Discussion: https://postgr.es/m/202403041517.3a35jw53os65@alvherre.pgsql
* Rework locking code in GetMultiXactIdMembersAlvaro Herrera2024-03-04
| | | | | | | | | | After commit 53c2a97a9266, the code flow around the "retry" goto label in GetMultiXactIdMembers was confused about what was possible: we never return there with a held lock, so there's no point in testing for one. This realization lets us simplify the code a bit. While at it, make the scope of a couple of local variables in the same function a bit tighter. Per Coverity.
* Simplify coding in slru.cAlvaro Herrera2024-03-04
| | | | | | | | | New code in 53c2a97a9266 uses direct array access to shared->bank_locks[bankno].lock which can be made a little bit more legible by using the SimpleLruGetBankLock helper function. Nothing terribly serious, but let's add some clarity. Discussion: https://postgr.es/m/202403041517.3a35jw53os65@alvherre.pgsql
* 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
* Remove unused ParallelWorkerInfo.pid fieldHeikki Linnakangas2024-03-04
| | | | | | | The pid was originally used in error context of messages propagated from parallel workers, but commit 292794f82b removed that. If the need arises in the future, you can also get the pid with "shm_mq_get_sender(pcxt->worker[i].error_mqh)->pid".
* Add regression test for restart points during promotionMichael Paquier2024-03-04
| | | | | | | | | | | | | | | | | | | | | | | | | | This test serves as a way to demonstrate how to use the features introduced in 37b369dc67bc, while providing coverage for 7863ee4def65 that caused the startup process to throw "PANIC: could not locate a valid checkpoint record" when starting recovery. The test checks that a node is able to properly restart following a crash when a restart point was finishing across a promotion, with an injection point added in the middle of CreateRestartPoint() to stop the restartpoint in flight. Note that this test fails when 7863ee4def65 is reverted. Kyotaro Horiguchi is the original author of this test, that has been originally posted on the thread where 7863ee4def65 was discussed. I have just upgraded and polished it to rely on injection points, making it much cheaper to reproduce the failure. This test requires injection points to be enabled in the builds, hence meson and ./configure need an update to pass this knowledge down to the test. The name of the new injection point follows the same naming convention as 6a1ea02c491d. The Makefile's EXTRA_INSTALL of recovery TAP tests is updated to include modules/injection_points. Author: Kyotaro Horiguchi, Michael Paquier Reviewed-by: Andrey Borodin, Bertrand Drouvot Discussion: https://postgr.es/m/ZdLuxBk5hGpol91B@paquier.xyz
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