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* Handle elog(FATAL) during ROLLBACK more robustly.Tom Lane2017-08-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Stress testing by Andreas Seltenreich disclosed longstanding problems that occur if a FATAL exit (e.g. due to receipt of SIGTERM) occurs while we are trying to execute a ROLLBACK of an already-failed transaction. In such a case, xact.c is in TBLOCK_ABORT state, so that AbortOutOfAnyTransaction would skip AbortTransaction and go straight to CleanupTransaction. This led to an assert failure in an assert-enabled build (due to the ROLLBACK's portal still having a cleanup hook) or without assertions, to a FATAL exit complaining about "cannot drop active portal". The latter's not disastrous, perhaps, but it's messy enough to want to improve it. We don't really want to run all of AbortTransaction in this code path. The minimum required to clean up the open portal safely is to do AtAbort_Memory and AtAbort_Portals. It seems like a good idea to do AtAbort_Memory unconditionally, to be entirely sure that we are starting with a safe CurrentMemoryContext. That means that if the main loop in AbortOutOfAnyTransaction does nothing, we need an extra step at the bottom to restore CurrentMemoryContext = TopMemoryContext, which I chose to do by invoking AtCleanup_Memory. This'll result in calling AtCleanup_Memory twice in many of the paths through this function, but that seems harmless and reasonably inexpensive. The original motivation for the assertion in AtCleanup_Portals was that we wanted to be sure that any user-defined code executed as a consequence of the cleanup hook runs during AbortTransaction not CleanupTransaction. That still seems like a valid concern, and now that we've seen one case of the assertion firing --- which means that exactly that would have happened in a production build --- let's replace the Assert with a runtime check. If we see the cleanup hook still set, we'll emit a WARNING and just drop the hook unexecuted. This has been like this a long time, so back-patch to all supported branches. Discussion: https://postgr.es/m/877ey7bmun.fsf@ansel.ydns.eu
* Remove AtEOXact_CatCache().Tom Lane2017-08-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The sole useful effect of this function, to check that no catcache entries have positive refcounts at transaction end, has really been obsolete since we introduced ResourceOwners in PG 8.1. We reduced the checks to assertions years ago, so that the function was a complete no-op in production builds. There have been previous discussions about removing it entirely, but consensus up to now was that it had some small value as a cross-check for bugs in the ResourceOwner logic. However, it now emerges that it's possible to trigger these assertions if you hit an assert-enabled backend with SIGTERM during a call to SearchCatCacheList, because that function temporarily increases the refcounts of entries it's intending to add to a catcache list construct. In a normal ERROR scenario, the extra refcounts are cleaned up by SearchCatCacheList's PG_CATCH block; but in a FATAL exit we do a transaction abort and exit without ever executing PG_CATCH handlers. There's a case to be made that this is a generic hazard and we should consider restructuring elog(FATAL) handling so that pending PG_CATCH handlers do get run. That's pretty scary though: it could easily create more problems than it solves. Preliminary stress testing by Andreas Seltenreich suggests that there are not many live problems of this ilk, so we rejected that idea. There are more-localized ways to fix the problem; the most principled one would be to use PG_ENSURE_ERROR_CLEANUP instead of plain PG_TRY. But adding cycles to SearchCatCacheList isn't very appealing. We could also weaken the assertions in AtEOXact_CatCache in some more or less ad-hoc way, but that just makes its raison d'etre even less compelling. In the end, the most reasonable solution seems to be to just remove AtEOXact_CatCache altogether, on the grounds that it's not worth trying to fix it. It hasn't found any bugs for us in many years. Per report from Jeevan Chalke. Back-patch to all supported branches. Discussion: https://postgr.es/m/CAM2+6=VEE30YtRQCZX7_sCFsEpoUkFBV1gZazL70fqLn8rcvBA@mail.gmail.com
* Fix double shared memory allocation.Teodor Sigaev2017-07-21
| | | | | | | | | | | SLRU buffer lwlocks are allocated twice by oversight in commit fe702a7b3f9f2bc5bf6d173166d7d55226af82c8 where that locks were moved to separate tranche. The bug doesn't have user-visible effects except small overspending of shared memory. Backpatch to 9.6 where it was introduced. Alexander Korotkov with small editorization by me.
* Fix typo in commentAlvaro Herrera2017-06-22
| | | | | | | | Once upon a time, WAL pointers could be NULL, but no longer. We talk about "valid" now. Reported-by: Amit Langote Discussion: https://postgr.es/m/33e9617d-27f1-eee8-3311-e27af98eaf2b@lab.ntt.co.jp
* Fix possibility of creating a "phantom" segment after promotion.Andres Freund2017-06-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When promoting a standby just after a XLOG_SWITCH record was replayed, and next segment(s) are already are locally available (via walsender, restore_command + trigger/recovery target), that segment could accidentally be recycled onto the past of the new timeline. Later checkpointer would create a .ready file for it, assuming there was an error during creation, and it would get archived. That causes trouble if another standby is later brought up from a basebackup from before the timeline creation, because it would try to read the segment, because XLogFileReadAnyTLI just tries all possible timelines, which doesn't have valid contents. Thus replay would fail. The problem, if already occurred, can be fixed by removing the segment and/or having restore_command filter it out. The reason for the creation of such "phantom" segments was, that after an XLOG_SWITCH record the EndOfLog variable points to the beginning of the next segment, and RemoveXlogFile() used XLByteToPrevSeg(). Normally RemoveXlogFile() doing so is harmless, because the last segment will still exist preventing InstallXLogFileSegment() from causing harm, but just after promotion there's no previous segment on the new timeline. Fix that by using XLByteToSeg() instead of XLByteToPrevSeg(). Author: Andres Freund Reported-By: Greg Burek Discussion: https://postgr.es/m/20170619073026.zcwpe6mydsaz5ygd@alap3.anarazel.de Backpatch: 9.2-, bug older than all supported versions
* Prevent possibility of panics during shutdown checkpoint.Andres Freund2017-06-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the checkpointer writes the shutdown checkpoint, it checks afterwards whether any WAL has been written since it started and throws a PANIC if so. At that point, only walsenders are still active, so one might think this could not happen, but walsenders can also generate WAL, for instance in BASE_BACKUP and logical decoding related commands (e.g. via hint bits). So they can trigger this panic if such a command is run while the shutdown checkpoint is being written. To fix this, divide the walsender shutdown into two phases. First, checkpointer, itself triggered by postmaster, sends a PROCSIG_WALSND_INIT_STOPPING signal to all walsenders. If the backend is idle or runs an SQL query this causes the backend to shutdown, if logical replication is in progress all existing WAL records are processed followed by a shutdown. Otherwise this causes the walsender to switch to the "stopping" state. In this state, the walsender will reject any further replication commands. The checkpointer begins the shutdown checkpoint once all walsenders are confirmed as stopping. When the shutdown checkpoint finishes, the postmaster sends us SIGUSR2. This instructs walsender to send any outstanding WAL, including the shutdown checkpoint record, wait for it to be replicated to the standby, and then exit. Author: Andres Freund, based on an earlier patch by Michael Paquier Reported-By: Fujii Masao, Andres Freund Reviewed-By: Michael Paquier Discussion: https://postgr.es/m/20170602002912.tqlwn4gymzlxpvs2@alap3.anarazel.de Backpatch: 9.4, where logical decoding was introduced
* Fix new warnings from GCC 7Peter Eisentraut2017-05-16
| | | | | This addresses the new warning types -Wformat-truncation -Wformat-overflow that are part of -Wall, via -Wformat, in GCC 7.
* Fix order of arguments to SubTransSetParent().Tom Lane2017-04-23
| | | | | | | | | | | | | | ProcessTwoPhaseBuffer (formerly StandbyRecoverPreparedTransactions) mixed up the parent and child XIDs when calling SubTransSetParent to record the transactions' relationship in pg_subtrans. Remarkably, analysis by Simon Riggs suggests that this doesn't lead to visible problems (at least, not in non-Assert builds). That might explain why we'd not noticed it before. Nonetheless, it's surely wrong. This code was born broken, so back-patch to all supported branches. Discussion: https://postgr.es/m/20110.1492905318@sss.pgh.pa.us
* Avoid passing function pointers across process boundaries.Tom Lane2017-04-15
| | | | | | | | | | | | This back-patches commit 32470825d36d99a81347ee36c181d609c952c061 into 9.6, primarily to make buildfarm member culicidae happy. Unlike the HEAD patch, avoid changing the existing API of CreateParallelContext; instead we just switch to using CreateParallelContextForExternalFunction, even for core functions. Petr Jelinek, with a bunch of basically-cosmetic adjustments by me Discussion: https://postgr.es/m/548f9c1d-eafa-e3fa-9da8-f0cc2f654e60@2ndquadrant.com
* Don't use bgw_main even to specify in-core bgworker entrypoints.Robert Haas2017-03-31
| | | | | | | | | | | | | | | On EXEC_BACKEND builds, this can fail if ASLR is in use. Backpatch to 9.5. On master, completely remove the bgw_main field completely, since there is no situation in which it is safe for an EXEC_BACKEND build. On 9.6 and 9.5, leave the field intact to avoid breaking things for third-party code that doesn't care about working under EXEC_BACKEND. Prior to 9.5, there are no in-core bgworker entrypoints. Petr Jelinek, reviewed by me. Discussion: http://postgr.es/m/09d8ad33-4287-a09b-a77f-77f8761adb5e@2ndquadrant.com
* Suppress implicit-conversion warnings seen with newer clang versions.Tom Lane2017-03-28
| | | | | | | | | | | | | | | We were assigning values near 255 through "char *" pointers. On machines where char is signed, that's not entirely kosher, and it's reasonable for compilers to warn about it. A better solution would be to change the pointer type to "unsigned char *", but that would be vastly more invasive. For the moment, let's just apply this simple backpatchable solution. Aleksander Alekseev Discussion: https://postgr.es/m/20170220141239.GD12278@e733.localdomain Discussion: https://postgr.es/m/2839.1490714708@sss.pgh.pa.us
* Fix backup cancelingTeodor Sigaev2017-03-24
| | | | | | | | | | | | | | | | | Assert-enabled build crashes but without asserts it works by wrong way: it may not reset forcing full page write and preventing from starting exclusive backup with the same name as cancelled. Patch replaces pair of booleans nonexclusive_backup_running/exclusive_backup_running to single enum to correctly describe backup state. Backpatch to 9.6 where bug was introduced Reported-by: David Steele Authors: Michael Paquier, David Steele Reviewed-by: Anastasia Lubennikova https://commitfest.postgresql.org/13/1068/
* Spelling fixesPeter Eisentraut2017-03-14
| | | | From: Josh Soref <jsoref@gmail.com>
* Fix incorrect variable datatypeMagnus Hagander2017-02-28
| | | | | | | Both datatypes map to the same underlying one which is why it still worked, but we should use the correct type. Author: Kyotaro HORIGUCHI
* Fix typos in comments.Heikki Linnakangas2017-02-06
| | | | | | | | | Backpatch to all supported versions, where applicable, to make backpatching of future fixes go more smoothly. Josh Soref Discussion: https://www.postgresql.org/message-id/CACZqfqCf+5qRztLPgmmosr-B0Ye4srWzzw_mo4c_8_B_mtjmJQ@mail.gmail.com
* Don't count background workers against a user's connection limit.Andrew Dunstan2017-02-01
| | | | | | | | | | Doing so doesn't seem to be within the purpose of the per user connection limits, and has particularly unfortunate effects in conjunction with parallel queries. Backpatch to 9.6 where parallel queries were introduced. David Rowley, reviewed by Robert Haas and Albe Laurenz.
* Fix an assertion failure related to an exclusive backup.Fujii Masao2017-01-17
| | | | | | | | | | | | | | | | | | | | | | Previously multiple sessions could execute pg_start_backup() and pg_stop_backup() to start and stop an exclusive backup at the same time. This could trigger the assertion failure of "FailedAssertion("!(XLogCtl->Insert.exclusiveBackup)". This happend because, even while pg_start_backup() was starting an exclusive backup, other session could run pg_stop_backup() concurrently and mark the backup as not-in-progress unconditionally. This patch introduces ExclusiveBackupState indicating the state of an exclusive backup. This state is used to ensure that there is only one session running pg_start_backup() or pg_stop_backup() at the same time, to avoid the assertion failure. Back-patch to all supported versions. Author: Michael Paquier Reviewed-By: Kyotaro Horiguchi and me Reported-By: Andreas Seltenreich Discussion: <87mvktojme.fsf@credativ.de>
* Bring some clarity to the defaults for the xxx_flush_after parameters.Tom Lane2016-11-25
| | | | | | | | | | | | | | | | | | | | | | | | | | Instead of confusingly stating platform-dependent defaults for these parameters in the comments in postgresql.conf.sample (with the main entry being a lie on Linux), teach initdb to install the correct platform-dependent value in postgresql.conf, similarly to the way we handle other platform-dependent defaults. This won't do anything for existing 9.6 installations, but since it's effectively only a documentation improvement, that seems OK. Since this requires initdb to have access to the default values, move the #define's for those to pg_config_manual.h; the original placement in bufmgr.h is unworkable because that file can't be included by frontend programs. Adjust the default value for wal_writer_flush_after so that it is 1MB regardless of XLOG_BLCKSZ, conforming to what is stated in both the SGML docs and postgresql.conf. (We could alternatively make it scale with XLOG_BLCKSZ, but I'm not sure I see the point.) Copy-edit related SGML documentation. Fabien Coelho and Tom Lane, per a gripe from Tomas Vondra. Discussion: <30ebc6e3-8358-09cf-44a8-578252938424@2ndquadrant.com>
* Fix commit_ts for FrozenXid and BootstrapXidAlvaro Herrera2016-11-24
| | | | | | | | | | | | | | | | Previously, requesting commit timestamp for transactions FrozenTransactionId and BootstrapTransactionId resulted in an error. But since those values can validly appear in committed tuples' Xmin, this behavior is unhelpful and error prone: each caller would have to special-case those values before requesting timestamp data for an Xid. We already have a perfectly good interface for returning "the Xid you requested is too old for us to have commit TS data for it", so let's use that instead. Backpatch to 9.5, where commit timestamps appeared. Author: Craig Ringer Discussion: https://www.postgresql.org/message-id/CAMsr+YFM5Q=+ry3mKvWEqRTxrB0iU3qUSRnS28nz6FJYtBwhJg@mail.gmail.com
* Fix possible pg_basebackup failure on standby with "include WAL".Robert Haas2016-10-27
| | | | | | | | | | | | | | | If a restartpoint flushed no dirty buffers, it could fail to update the minimum recovery point, leading to a minimum recovery point prior to the starting REDO location. perform_base_backup() would interpret that as meaning that no WAL files at all needed to be included in the backup, failing an internal sanity check. To fix, have restartpoints always update the minimum recovery point to just after the checkpoint record itself, so that the file (or files) containing the checkpoint record will always be included in the backup. Code by Amit Kapila, per a design suggestion by me, with some additional work on the code comment by me. Test case by Michael Paquier. Report by Kyotaro Horiguchi.
* Preserve commit timestamps across clean restartAlvaro Herrera2016-10-24
| | | | | | | | | An oversight in setting the boundaries of known commit timestamps during startup caused old commit timestamps to become inaccessible after a server restart. Author and reporter: Julien Rouhaud Review, test code: Craig Ringer
* Fix corruption of 2PC recovery with subxactsSimon Riggs2016-09-09
| | | | | | | | Reading 2PC state files during recovery was borked, causing corruptions during recovery. Effect limited to servers with 2PC, subtransactions and recovery/replication. Stas Kelvich, reviewed by Michael Paquier and Pavan Deolasee
* Fix minor memory leak in Standby startupSimon Riggs2016-09-08
| | | | | | | | | | StandbyRecoverPreparedTransactions() leaked the buffer used for two phase state file. This was leaked once at startup and at every shutdown checkpoint seen. Backpatch to 9.6 Stas Kelvich
* Prevent starting a standalone backend with standby_mode on.Tom Lane2016-08-31
| | | | | | | | | | | | | | | | | | | This can't really work because standby_mode expects there to be more WAL arriving, which there will not ever be because there's no WAL receiver process to fetch it. Moreover, if standby_mode is on then hot standby might also be turned on, causing even more strangeness because that expects read-only sessions to be executing in parallel. Bernd Helmle reported a case where btree_xlog_delete_get_latestRemovedXid got confused, but rather than band-aiding individual problems it seems best to prevent getting anywhere near this state in the first place. Back-patch to all supported branches. In passing, also fix some omissions of errcodes in other ereport's in readRecoveryCommandFile(). Michael Paquier (errcode hacking by me) Discussion: <00F0B2CEF6D0CEF8A90119D4@eje.credativ.lan>
* Fix pg_xlogdump so that it handles cross-page XLP_FIRST_IS_CONTRECORD record.Fujii Masao2016-08-29
| | | | | | | | | | | | | | | | | | Previously pg_xlogdump failed to dump the contents of the WAL file if the file starts with the continuation WAL record which spans more than one pages. Since pg_xlogdump assumed that the continuation record always fits on a page, it could not find the valid WAL record to start reading from in that case. This patch changes pg_xlogdump so that it can handle a continuation WAL record which crosses a page boundary and find the valid record to start reading from. Back-patch to 9.3 where pg_xlogdump was introduced. Author: Pavan Deolasee Reviewed-By: Michael Paquier and Craig Ringer Discussion: CABOikdPsPByMiG6J01DKq6om2+BNkxHTPkOyqHM2a4oYwGKsqQ@mail.gmail.com
* Add macros to make AllocSetContextCreate() calls simpler and safer.Tom Lane2016-08-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I found that half a dozen (nearly 5%) of our AllocSetContextCreate calls had typos in the context-sizing parameters. While none of these led to especially significant problems, they did create minor inefficiencies, and it's now clear that expecting people to copy-and-paste those calls accurately is not a great idea. Let's reduce the risk of future errors by introducing single macros that encapsulate the common use-cases. Three such macros are enough to cover all but two special-purpose contexts; those two calls can be left as-is, I think. While this patch doesn't in itself improve matters for third-party extensions, it doesn't break anything for them either, and they can gradually adopt the simplified notation over time. In passing, change TopMemoryContext to use the default allocation parameters. Formerly it could only be extended 8K at a time. That was probably reasonable when this code was written; but nowadays we create many more contexts than we did then, so that it's not unusual to have a couple hundred K in TopMemoryContext, even without considering various dubious code that sticks other things there. There seems no good reason not to let it use growing blocks like most other contexts. Back-patch to 9.6, mostly because that's still close enough to HEAD that it's easy to do so, and keeping the branches in sync can be expected to avoid some future back-patching pain. The bugs fixed by these changes don't seem to be significant enough to justify fixing them further back. Discussion: <21072.1472321324@sss.pgh.pa.us>
* Fix potential memory leakage from HandleParallelMessages().Tom Lane2016-08-26
| | | | | | | | | | | | | | | | HandleParallelMessages leaked memory into the caller's context. Since it's called from ProcessInterrupts, there is basically zero certainty as to what CurrentMemoryContext is, which means we could be leaking into long-lived contexts. Over the processing of many worker messages that would grow to be a problem. Things could be even worse than just a leak, if we happened to service the interrupt while ErrorContext is current: elog.c thinks it can reset that on its own whim, possibly yanking storage out from under HandleParallelMessages. Give HandleParallelMessages its own dedicated context instead, which we can reset during each call to ensure there's no accumulation of wasted memory. Discussion: <16610.1472222135@sss.pgh.pa.us>
* Fix logic for adding "parallel worker" context line to worker errors.Tom Lane2016-08-26
| | | | | | | | | The previous coding here was capable of adding a "parallel worker" context line to errors that were not, in fact, returned from a parallel worker. Instead of using an errcontext callback to add that annotation, just paste it onto the message by hand; this looks uglier but is more reliable. Discussion: <19757.1472151987@sss.pgh.pa.us>
* Fix typosPeter Eisentraut2016-08-16
| | | | From: Alexander Law <exclusion@gmail.com>
* Block interrupts during HandleParallelMessages().Tom Lane2016-08-02
| | | | | | | | | | | | | | | | As noted by Alvaro, there are CHECK_FOR_INTERRUPTS() calls in the shm_mq.c functions called by HandleParallelMessages(). I believe they're all unreachable since we always pass nowait = true, but it doesn't seem like a great idea to assume that no such call will ever be reachable from HandleParallelMessages(). If that did happen, there would be a risk of a recursive call to HandleParallelMessages(), which it does not appear to be designed for --- for example, there's nothing that would prevent out-of-order processing of received messages. And certainly such cases cannot easily be tested. So let's prevent it by holding off interrupts for the duration of the function. Back-patch to 9.5 which contains identical code. Discussion: <14869.1470083848@sss.pgh.pa.us>
* Minor cleanup for access/transam/parallel.c.Tom Lane2016-08-01
| | | | | | | | | | | | | | | | | | | | ParallelMessagePending *must* be marked volatile, because it's set by a signal handler. On the other hand, it's pointless for HandleParallelMessageInterrupt to save/restore errno; that must be, and is, done at the outer level of the SIGUSR1 signal handler. Calling CHECK_FOR_INTERRUPTS() inside HandleParallelMessages, which itself is called from CHECK_FOR_INTERRUPTS(), seems both useless and hazardous. The comment claiming that this is needed to handle the error queue going away is certainly misguided, in any case. Improve a couple of error message texts, and use ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE to report loss of parallel worker connection, since that's what's used in e.g. tqueue.c. (Maybe it would be worth inventing a dedicated ERRCODE for this type of failure? But I do not think ERRCODE_INTERNAL_ERROR is appropriate.) Minor stylistic cleanups.
* Message style improvementsPeter Eisentraut2016-07-28
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* Remove unused structure member.Robert Haas2016-07-21
| | | | Michael Paquier
* Fix start WAL filename for concurrent backups from standbyMagnus Hagander2016-07-11
| | | | | | | | | | On a standby, ThisTimelineID is always 0, so we would generate a filename in timeline 0 even for other timelines. Instead, use starttli which we have retreived from the controlfile. Report by: Francesco Canovai in bug #14230 Author: Marco Nenciarini Reviewed by: Michael Paquier and Amit Kapila
* Fix several mistakes around parallel workers and client_encoding.Robert Haas2016-06-30
| | | | | | | | | | | | | | | | | | | | | | | | | Previously, workers sent data to the leader using the client encoding. That mostly worked, but the leader the converted the data back to the server encoding. Since not all encoding conversions are reversible, that could provoke failures. Fix by using the database encoding for all communication between worker and leader. Also, while temporary changes to GUC settings, as from the SET clause of a function, are in general OK for parallel query, changing client_encoding this way inside of a parallel worker is not OK. Previously, that would have confused the leader; with these changes, it would not confuse the leader, but it wouldn't do anything either. So refuse such changes in parallel workers. Also, the previous code naively assumed that when it received a NotifyResonse from the worker, it could pass that directly back to the user. But now that worker-to-leader communication always uses the database encoding, that's clearly no longer correct - though, actually, the old way was always broken for V2 clients. So disassemble and reconstitute the message instead. Issues reported by Peter Eisentraut. Patch by me, reviewed by Peter Eisentraut.
* Fix handling of multixacts predating pg_upgradeAlvaro Herrera2016-06-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After pg_upgrade, it is possible that some tuples' Xmax have multixacts corresponding to the old installation; such multixacts cannot have running members anymore. In many code sites we already know not to read them and clobber them silently, but at least when VACUUM tries to freeze a multixact or determine whether one needs freezing, there's an attempt to resolve it to its member transactions by calling GetMultiXactIdMembers, and if the multixact value is "in the future" with regards to the current valid multixact range, an error like this is raised: ERROR: MultiXactId 123 has not been created yet -- apparent wraparound and vacuuming fails. Per discussion with Andrew Gierth, it is completely bogus to try to resolve multixacts coming from before a pg_upgrade, regardless of where they stand with regards to the current valid multixact range. It's possible to get from under this problem by doing SELECT FOR UPDATE of the problem tuples, but if tables are large, this is slow and tedious, so a more thorough solution is desirable. To fix, we realize that multixacts in xmax created in 9.2 and previous have a specific bit pattern that is never used in 9.3 and later (we already knew this, per comments and infomask tests sprinkled in various places, but we weren't leveraging this knowledge appropriately). Whenever the infomask of the tuple matches that bit pattern, we just ignore the multixact completely as if Xmax wasn't set; or, in the case of tuple freezing, we act as if an unwanted value is set and clobber it without decoding. This guarantees that no errors will be raised, and that the values will be progressively removed until all tables are clean. Most callers of GetMultiXactIdMembers are patched to recognize directly that the value is a removable "empty" multixact and avoid calling GetMultiXactIdMembers altogether. To avoid changing the signature of GetMultiXactIdMembers() in back branches, we keep the "allow_old" boolean flag but rename it to "from_pgupgrade"; if the flag is true, we always return an empty set instead of looking up the multixact. (I suppose we could remove the argument in the master branch, but I chose not to do so in this commit). This was broken all along, but the error-facing message appeared first because of commit 8e9a16ab8f7f and was partially fixed in a25c2b7c4db3. This fix, backpatched all the way back to 9.3, goes approximately in the same direction as a25c2b7c4db3 but should cover all cases. Bug analysis by Andrew Gierth and Álvaro Herrera. A number of public reports match this bug: https://www.postgresql.org/message-id/20140330040029.GY4582@tamriel.snowman.net https://www.postgresql.org/message-id/538F3D70.6080902@publicrelay.com https://www.postgresql.org/message-id/556439CF.7070109@pscs.co.uk https://www.postgresql.org/message-id/SG2PR06MB0760098A111C88E31BD4D96FB3540@SG2PR06MB0760.apcprd06.prod.outlook.com https://www.postgresql.org/message-id/20160615203829.5798.4594@wrigleys.postgresql.org
* Finish up XLOG_HINT renamingAlvaro Herrera2016-06-17
| | | | | | | Commit b8fd1a09f3 renamed XLOG_HINT to XLOG_FPI, but neglected two places. Backpatch to 9.3, like that commit.
* Remove PID from 'parallel worker' context message.Robert Haas2016-06-17
| | | | Discussion: <bfd204ab-ab1a-792a-b345-0274a09a4b5f@2ndquadrant.com>
* Fix fuzzy thinking in ReinitializeParallelDSM().Tom Lane2016-06-16
| | | | | | | | | The fact that no workers were successfully launched in the previous iteration does not excuse us from setting up properly to try again. This appears to explain crashes I saw in parallel regression testing due to error_mqh being NULL when it shouldn't be. Minor other cosmetic fixes too.
* Improve the situation for parallel query versus temp relations.Tom Lane2016-06-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Transmit the leader's temp-namespace state to workers. This is important because without it, the workers do not really have the same search path as the leader. For example, there is no good reason (and no extant code either) to prevent a worker from executing a temp function that the leader created previously; but as things stood it would fail to find the temp function, and then either fail or execute the wrong function entirely. We still prohibit a worker from creating a temp namespace on its own. In effect, a worker can only see the session's temp namespace if the leader had created it before starting the worker, which seems like the right semantics. Also, transmit the leader's BackendId to workers, and arrange for workers to use that when determining the physical file path of a temp relation belonging to their session. While the original intent was to prevent such accesses entirely, there were a number of holes in that, notably in places like dbsize.c which assume they can safely access temp rels of other sessions anyway. We might as well get this right, as a small down payment on someday allowing workers to access the leader's temp tables. (With this change, directly using "MyBackendId" as a relation or buffer backend ID is deprecated; you should use BackendIdForTempRelations() instead. I left a couple of such uses alone though, as they're not going to be reachable in parallel workers until we do something about localbuf.c.) Move the thou-shalt-not-access-thy-leader's-temp-tables prohibition down into localbuf.c, which is where it actually matters, instead of having it in relation_open(). This amounts to recognizing that access to temp tables' catalog entries is perfectly safe in a worker, it's only the data in local buffers that is problematic. Having done all that, we can get rid of the test in has_parallel_hazard() that says that use of a temp table's rowtype is unsafe in parallel workers. That test was unduly expensive, and if we really did need such a prohibition, that was not even close to being a bulletproof guard for it. (For example, any user-defined function executed in a parallel worker might have attempted such access.)
* pgindent run for 9.6Robert Haas2016-06-09
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* Message style and wording fixesPeter Eisentraut2016-06-07
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* Fix various common mispellings.Greg Stark2016-06-03
| | | | | | | | | | Mostly these are just comments but there are a few in documentation and a handful in code and tests. Hopefully this doesn't cause too much unnecessary pain for backpatching. I relented from some of the most common like "thru" for that reason. The rest don't seem numerous enough to cause problems. Thanks to Kevin Lyda's tool https://pypi.python.org/pypi/misspellings
* Allocate all page images at once in generic wal interfaceTeodor Sigaev2016-05-17
| | | | | | That reduces number of allocation. Per gripe from Michael Paquier and Tom Lane suggestion.
* Correctly align page's images in generic wal APITeodor Sigaev2016-05-17
| | | | | | | Page image should be MAXALIGN'ed because existing code could directly align pointers in page instead of align offset from beginning of page. Found during play with indexes as extenstion, Alexander Korotkov and me
* Fix bogus commentsAlvaro Herrera2016-05-12
| | | | | | Some comments mentioned XLogReplayBuffer, but there's no such function: that was an interim name for a function that got renamed to XLogReadBufferForRedo, before commit 2c03216d831160 was pushed.
* Fix poorly-worded log message.Tom Lane2016-05-08
| | | | Euler Taveira
* Use mul_size when multiplying by the number of parallel workers.Robert Haas2016-05-06
| | | | | | | | | | That way, if the result overflows size_t, you'll get an error instead of undefined behavior, which seems like a plus. This also has the effect of casting the number of workers from int to Size, which is better because it's harder to overflow int than size_t. Dilip Kumar reported this issue and provided a patch upon which this patch is based, but his version did use mul_size.
* Revert timeline following in replication slotsAlvaro Herrera2016-05-04
| | | | | | | | | This reverts commits f07d18b6e94d, 82c83b337202, 3a3b309041b0, and 24c5f1a103ce. This feature has shown enough immaturity that it was deemed better to rip it out before rushing some more fixes at the last minute. There are discussions on larger changes in this area for the next release.
* Emit invalidations to standby for transactions without xid.Andres Freund2016-04-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | So far, when a transaction with pending invalidations, but without an assigned xid, committed, we simply ignored those invalidation messages. That's problematic, because those are actually sent for a reason. Known symptoms of this include that existing sessions on a hot-standby replica sometimes fail to notice new concurrently built indexes and visibility map updates. The solution is to WAL log such invalidations in transactions without an xid. We considered to alternatively force-assign an xid, but that'd be problematic for vacuum, which might be run in systems with few xids. Important: This adds a new WAL record, but as the patch has to be back-patched, we can't bump the WAL page magic. This means that standbys have to be updated before primaries; otherwise "PANIC: standby_redo: unknown op code 32" errors can be encountered. XXX: Reported-By: Васильев Дмитрий, Masahiko Sawada Discussion: CAB-SwXY6oH=9twBkXJtgR4UC1NqT-vpYAtxCseME62ADwyK5OA@mail.gmail.com CAD21AoDpZ6Xjg=gFrGPnSn4oTRRcwK1EBrWCq9OqOHuAcMMC=w@mail.gmail.com