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* Avoid creation of the free space map for small heap relations, take 2.Amit Kapila2019-02-04
| | | | | | | | | | | | | | | | | | | | | | | | Previously, all heaps had FSMs. For very small tables, this means that the FSM took up more space than the heap did. This is wasteful, so now we refrain from creating the FSM for heaps with 4 pages or fewer. If the last known target block has insufficient space, we still try to insert into some other page before giving up and extending the relation, since doing otherwise leads to table bloat. Testing showed that trying every page penalized performance slightly, so we compromise and try every other page. This way, we visit at most two pages. Any pages with wasted free space become visible at next relation extension, so we still control table bloat. As a bonus, directly attempting one or two pages can even be faster than consulting the FSM would have been. Once the FSM is created for a heap we don't remove it even if somebody deletes all the rows from the corresponding relation. We don't think it is a useful optimization as it is quite likely that relation will again grow to the same size. Author: John Naylor, Amit Kapila Reviewed-by: Amit Kapila Tested-by: Mithun C Y Discussion: https://www.postgresql.org/message-id/CAJVSVGWvB13PzpbLEecFuGFc5V2fsO736BsdTakPiPAcdMM5tQ@mail.gmail.com
* Add shared_memory_type GUC.Thomas Munro2019-02-03
| | | | | | | | | | | | | | Since 9.3 we have used anonymous shared mmap for our main shared memory region, except in EXEC_BACKEND builds. Provide a GUC so that users can opt for System V shared memory once again, like in 9.2 and earlier. A later patch proposes to add huge/large page support for AIX, which requires System V shared memory and provided the motivation to revive this possibility. It may also be useful on some BSDs. Author: Andres Freund (revived and documented by Thomas Munro) Discussion: https://postgr.es/m/HE1PR0202MB28126DB4E0B6621CC6A1A91286D90%40HE1PR0202MB2812.eurprd02.prod.outlook.com Discussion: https://postgr.es/m/2AE143D2-87D3-4AD1-AC78-CE2258230C05%40FreeBSD.org
* Revert "Avoid creation of the free space map for small heap relations."Amit Kapila2019-01-28
| | | | This reverts commit ac88d2962a96a9c7e83d5acfc28fe49a72812086.
* Avoid creation of the free space map for small heap relations.Amit Kapila2019-01-28
| | | | | | | | | | | | | | | | | | | | | | | | Previously, all heaps had FSMs. For very small tables, this means that the FSM took up more space than the heap did. This is wasteful, so now we refrain from creating the FSM for heaps with 4 pages or fewer. If the last known target block has insufficient space, we still try to insert into some other page before giving up and extending the relation, since doing otherwise leads to table bloat. Testing showed that trying every page penalized performance slightly, so we compromise and try every other page. This way, we visit at most two pages. Any pages with wasted free space become visible at next relation extension, so we still control table bloat. As a bonus, directly attempting one or two pages can even be faster than consulting the FSM would have been. Once the FSM is created for a heap we don't remove it even if somebody deletes all the rows from the corresponding relation. We don't think it is a useful optimization as it is quite likely that relation will again grow to the same size. Author: John Naylor with design inputs and some code contribution by Amit Kapila Reviewed-by: Amit Kapila Tested-by: Mithun C Y Discussion: https://www.postgresql.org/message-id/CAJVSVGWvB13PzpbLEecFuGFc5V2fsO736BsdTakPiPAcdMM5tQ@mail.gmail.com
* In bootstrap mode, don't allow the creation of files if they don't alreadyAmit Kapila2019-01-28
| | | | | | | | | | | | | | | | | exist. In commit's b9d01fe288 and 3908473c80, we have added some code where we allowed the creation of files during mdopen even if they didn't exist during the bootstrap mode. The later commit obviates the need for same. This was harmless code till now but with an upcoming feature where we don't allow to create FSM for small tables, this will needlessly create FSM files. Author: John Naylor Reviewed-by: Amit Kapila Discussion: https://www.postgresql.org/message-id/CAJVSVGWvB13PzpbLEecFuGFc5V2fsO736BsdTakPiPAcdMM5tQ@mail.gmail.com https://www.postgresql.org/message-id/CAA4eK1KsET6sotf+rzOTQfb83pzVEzVhbQi1nxGFYVstVWXUGw@mail.gmail.com
* Move remaining code from tqual.[ch] to heapam.h / heapam_visibility.c.Andres Freund2019-01-21
| | | | | | | | | | | | | | Given these routines are heap specific, and that there will be more generic visibility support in via table AM, it makes sense to move the prototypes to heapam.h (routines like HeapTupleSatisfiesVacuum will not be exposed in a generic fashion, because they are too storage specific). Similarly, the code in tqual.c is specific to heap, so moving it into access/heap/ makes sense. Author: Andres Freund Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
* Remove superfluous tqual.h includes.Andres Freund2019-01-21
| | | | | | | | | | | | Most of these had been obsoleted by 568d4138c / the SnapshotNow removal. This is is preparation for moving most of tqual.[ch] into either snapmgr.h or heapam.h, which in turn is in preparation for pluggable table AMs. Author: Andres Freund Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
* Replace uses of heap_open et al with the corresponding table_* function.Andres Freund2019-01-21
| | | | | Author: Andres Freund Discussion: https://postgr.es/m/20190111000539.xbv7s6w7ilcvm7dp@alap3.anarazel.de
* Replace heapam.h includes with {table, relation}.h where applicable.Andres Freund2019-01-21
| | | | | | | | | A lot of files only included heapam.h for relation_open, heap_open etc - replace the heapam.h include in those files with the narrower header. Author: Andres Freund Discussion: https://postgr.es/m/20190111000539.xbv7s6w7ilcvm7dp@alap3.anarazel.de
* Fix grammar mistakes in md.cMichael Paquier2019-01-10
| | | | | Author: Kirk Jamison Discussion: https://postgr.es/m/D09B13F772D2274BB348A310EE3027C640AC54@g01jpexmbkw24
* Update copyright for 2019Bruce Momjian2019-01-02
| | | | Backpatch-through: certain files through 9.4
* Remove configure switch --disable-strong-randomMichael Paquier2019-01-01
| | | | | | | | | | | | | | | | This removes a portion of infrastructure introduced by fe0a0b5 to allow compilation of Postgres in environments where no strong random source is available, meaning that there is no linking to OpenSSL and no /dev/urandom (Windows having its own CryptoAPI). No systems shipped this century lack /dev/urandom, and the buildfarm is actually not testing this switch at all, so just remove it. This simplifies particularly some backend code which included a fallback implementation using shared memory, and removes a set of alternate regression output files from pgcrypto. Author: Michael Paquier Reviewed-by: Tom Lane Discussion: https://postgr.es/m/20181230063219.GG608@paquier.xyz
* Have BufFileSize() ereport() on FileSize() failure.Peter Geoghegan2018-11-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move the responsibility for checking for and reporting a failure from the only current BufFileSize() caller, logtape.c, to BufFileSize() itself. Code within buffile.c is generally responsible for interfacing with fd.c to report irrecoverable failures. This seems like a convention that's worth sticking to. Reorganizing things this way makes it easy to make the error message raised in the event of BufFileSize() failure descriptive of the underlying problem. We're now clear on the distinction between temporary file name and BufFile name, and can show errno, confident that its value actually relates to the error being reported. In passing, an existing, similar buffile.c ereport() + errcode_for_file_access() site is changed to follow the same conventions. The API of the function BufFileSize() is changed by this commit, despite already being in a stable release (Postgres 11). This seems acceptable, since the BufFileSize() ABI was changed by commit aa551830421, which hasn't made it into a point release yet. Besides, it's difficult to imagine a third party BufFileSize() caller not just raising an error anyway, since BufFile state should be considered corrupt when BufFileSize() fails. Per complaint from Tom Lane. Discussion: https://postgr.es/m/26974.1540826748@sss.pgh.pa.us Backpatch: 11-, where shared BufFiles were introduced.
* Don't count zero-filled buffers as 'read' in EXPLAIN.Thomas Munro2018-11-28
| | | | | | | | | | | | | If you extend a relation, it should count as a block written, not read (we write a zero-filled block). If you ask for a zero-filled buffer, it shouldn't be counted as read or written. Later we might consider counting zero-filled buffers with a separate counter, if they become more common due to future work. Author: Thomas Munro Reviewed-by: Haribabu Kommi, Kyotaro Horiguchi, David Rowley Discussion: https://postgr.es/m/CAEepm%3D3JytB3KPpvSwXzkY%2Bdwc5zC8P8Lk7Nedkoci81_0E9rA%40mail.gmail.com
* Add WL_EXIT_ON_PM_DEATH pseudo-event.Thomas Munro2018-11-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Users of the WaitEventSet and WaitLatch() APIs can now choose between asking for WL_POSTMASTER_DEATH and then handling it explicitly, or asking for WL_EXIT_ON_PM_DEATH to trigger immediate exit on postmaster death. This reduces code duplication, since almost all callers want the latter. Repair all code that was previously ignoring postmaster death completely, or requesting the event but ignoring it, or requesting the event but then doing an unconditional PostmasterIsAlive() call every time through its event loop (which is an expensive syscall on platforms for which we don't have USE_POSTMASTER_DEATH_SIGNAL support). Assert that callers of WaitLatchXXX() under the postmaster remember to ask for either WL_POSTMASTER_DEATH or WL_EXIT_ON_PM_DEATH, to prevent future bugs. The only process that doesn't handle postmaster death is syslogger. It waits until all backends holding the write end of the syslog pipe (including the postmaster) have closed it by exiting, to be sure to capture any parting messages. By using the WaitEventSet API directly it avoids the new assertion, and as a by-product it may be slightly more efficient on platforms that have epoll(). Author: Thomas Munro Reviewed-by: Kyotaro Horiguchi, Heikki Linnakangas, Tom Lane Discussion: https://postgr.es/m/CAEepm%3D1TCviRykkUb69ppWLr_V697rzd1j3eZsRMmbXvETfqbQ%40mail.gmail.com, https://postgr.es/m/CAEepm=2LqHzizbe7muD7-2yHUbTOoF7Q+qkSD5Q41kuhttRTwA@mail.gmail.com
* Remove WITH OIDS support, change oid catalog column visibility.Andres Freund2018-11-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously tables declared WITH OIDS, including a significant fraction of the catalog tables, stored the oid column not as a normal column, but as part of the tuple header. This special column was not shown by default, which was somewhat odd, as it's often (consider e.g. pg_class.oid) one of the more important parts of a row. Neither pg_dump nor COPY included the contents of the oid column by default. The fact that the oid column was not an ordinary column necessitated a significant amount of special case code to support oid columns. That already was painful for the existing, but upcoming work aiming to make table storage pluggable, would have required expanding and duplicating that "specialness" significantly. WITH OIDS has been deprecated since 2005 (commit ff02d0a05280e0). Remove it. Removing includes: - CREATE TABLE and ALTER TABLE syntax for declaring the table to be WITH OIDS has been removed (WITH (oids[ = true]) will error out) - pg_dump does not support dumping tables declared WITH OIDS and will issue a warning when dumping one (and ignore the oid column). - restoring an pg_dump archive with pg_restore will warn when restoring a table with oid contents (and ignore the oid column) - COPY will refuse to load binary dump that includes oids. - pg_upgrade will error out when encountering tables declared WITH OIDS, they have to be altered to remove the oid column first. - Functionality to access the oid of the last inserted row (like plpgsql's RESULT_OID, spi's SPI_lastoid, ...) has been removed. The syntax for declaring a table WITHOUT OIDS (or WITH (oids = false) for CREATE TABLE) is still supported. While that requires a bit of support code, it seems unnecessary to break applications / dumps that do not use oids, and are explicit about not using them. The biggest user of WITH OID columns was postgres' catalog. This commit changes all 'magic' oid columns to be columns that are normally declared and stored. To reduce unnecessary query breakage all the newly added columns are still named 'oid', even if a table's column naming scheme would indicate 'reloid' or such. This obviously requires adapting a lot code, mostly replacing oid access via HeapTupleGetOid() with access to the underlying Form_pg_*->oid column. The bootstrap process now assigns oids for all oid columns in genbki.pl that do not have an explicit value (starting at the largest oid previously used), only oids assigned later by oids will be above FirstBootstrapObjectId. As the oid column now is a normal column the special bootstrap syntax for oids has been removed. Oids are not automatically assigned during insertion anymore, all backend code explicitly assigns oids with GetNewOidWithIndex(). For the rare case that insertions into the catalog via SQL are called for the new pg_nextoid() function can be used (which only works on catalog tables). The fact that oid columns on system tables are now normal columns means that they will be included in the set of columns expanded by * (i.e. SELECT * FROM pg_class will now include the table's oid, previously it did not). It'd not technically be hard to hide oid column by default, but that'd mean confusing behavior would either have to be carried forward forever, or it'd cause breakage down the line. While it's not unlikely that further adjustments are needed, the scope/invasiveness of the patch makes it worthwhile to get merge this now. It's painful to maintain externally, too complicated to commit after the code code freeze, and a dependency of a number of other patches. Catversion bump, for obvious reasons. Author: Andres Freund, with contributions by John Naylor Discussion: https://postgr.es/m/20180930034810.ywp2c7awz7opzcfr@alap3.anarazel.de
* Handle EPIPE more sanely when we close a pipe reading from a program.Tom Lane2018-11-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously, any program launched by COPY TO/FROM PROGRAM inherited the server's setting of SIGPIPE handling, i.e. SIG_IGN. Hence, if we were doing COPY FROM PROGRAM and closed the pipe early, the child process would see EPIPE on its output file and typically would treat that as a fatal error, in turn causing the COPY to report error. Similarly, one could get a failure report from a query that didn't read all of the output from a contrib/file_fdw foreign table that uses file_fdw's PROGRAM option. To fix, ensure that child programs inherit SIG_DFL not SIG_IGN processing of SIGPIPE. This seems like an all-around better situation since if the called program wants some non-default treatment of SIGPIPE, it would expect to have to set that up for itself. Then in COPY, if it's COPY FROM PROGRAM and we stop reading short of detecting EOF, treat a SIGPIPE exit from the called program as a non-error condition. This still allows us to report an error for any case where the called program gets SIGPIPE on some other file descriptor. As coded, we won't report a SIGPIPE if we stop reading as a result of seeing an in-band EOF marker (e.g. COPY BINARY EOF marker). It's somewhat debatable whether we should complain if the called program continues to transmit data after an EOF marker. However, it seems like we should avoid throwing error in any questionable cases, especially in a back-patched fix, and anyway it would take additional code to make such an error get reported consistently. Back-patch to v10. We could go further back, since COPY FROM PROGRAM has been around awhile, but AFAICS the only way to reach this situation using core or contrib is via file_fdw, which has only supported PROGRAM sources since v10. The COPY statement per se has no feature whereby it'd stop reading without having hit EOF or an error already. Therefore, I don't see any upside to back-patching further that'd outweigh the risk of complaints about behavioral change. Per bug #15449 from Eric Cyr. Patch by me, review by Etsuro Fujita and Kyotaro Horiguchi Discussion: https://postgr.es/m/15449-1cf737dd5929450e@postgresql.org
* PANIC on fsync() failure.Thomas Munro2018-11-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On some operating systems, it doesn't make sense to retry fsync(), because dirty data cached by the kernel may have been dropped on write-back failure. In that case the only remaining copy of the data is in the WAL. A subsequent fsync() could appear to succeed, but not have flushed the data. That means that a future checkpoint could apparently complete successfully but have lost data. Therefore, violently prevent any future checkpoint attempts by panicking on the first fsync() failure. Note that we already did the same for WAL data; this change extends that behavior to non-temporary data files. Provide a GUC data_sync_retry to control this new behavior, for users of operating systems that don't eject dirty data, and possibly forensic/testing uses. If it is set to on and the write-back error was transient, a later checkpoint might genuinely succeed (on a system that does not throw away buffers on failure); if the error is permanent, later checkpoints will continue to fail. The GUC defaults to off, meaning that we panic. Back-patch to all supported releases. There is still a narrow window for error-loss on some operating systems: if the file is closed and later reopened and a write-back error occurs in the intervening time, but the inode has the bad luck to be evicted due to memory pressure before we reopen, we could miss the error. A later patch will address that with a scheme for keeping files with dirty data open at all times, but we judge that to be too complicated to back-patch. Author: Craig Ringer, with some adjustments by Thomas Munro Reported-by: Craig Ringer Reviewed-by: Robert Haas, Thomas Munro, Andres Freund Discussion: https://postgr.es/m/20180427222842.in2e4mibx45zdth5%40alap3.anarazel.de
* Don't forget about failed fsync() requests.Thomas Munro2018-11-19
| | | | | | | | | | | | If fsync() fails, md.c must keep the request in its bitmap, so that future attempts will try again. Back-patch to all supported releases. Author: Thomas Munro Reviewed-by: Amit Kapila Reported-by: Andrew Gierth Discussion: https://postgr.es/m/87y3i1ia4w.fsf%40news-spur.riddles.org.uk
* Use 64 bit type for BufFileSize().Thomas Munro2018-11-15
| | | | | | | | | | | | | | | | | | | | | | | BufFileSize() can't use off_t, because it's only 32 bits wide on some systems. BufFile objects can have many 1GB segments so the total size can exceed 2^31. The only known client of the function is parallel CREATE INDEX, which was reported to fail when building large indexes on Windows. Though this is technically an ABI break on platforms with a 32 bit off_t and we might normally avoid back-patching it, the function is brand new and thus unlikely to have been discovered by extension authors yet, and it's fairly thoroughly broken on those platforms anyway, so just fix it. Defect in 9da0cc35. Bug #15460. Back-patch to 11, where this function landed. Author: Thomas Munro Reported-by: Paul van der Linden, Pavel Oskin Reviewed-by: Peter Geoghegan Discussion: https://postgr.es/m/15460-b6db80de822fa0ad%40postgresql.org Discussion: https://postgr.es/m/CAHDGBJP_GsESbTt4P3FZA8kMUKuYxjg57XHF7NRBoKnR%3DCAR-g%40mail.gmail.com
* Fix the initialization of atomic variables introduced by theAmit Kapila2018-11-13
| | | | | | | | | | | | | | group clearing mechanism. Commits 0e141c0fbb and baaf272ac9 introduced initialization of atomic variables in InitProcess which means that it's not safe to look at those for backends that aren't currently in use. Fix that by initializing them during postmaster startup. Reported-by: Andres Freund Author: Amit Kapila Backpatch-through: 9.6 Discussion: https://postgr.es/m/20181027104138.qmbbelopvy7cw2qv@alap3.anarazel.de
* Remove volatiles from {procarray,volatile}.c and fix memory ordering issue.Andres Freund2018-11-10
| | | | | | | | | | | | | | | | | | | | | | | The use of volatiles in procarray.c largely originated from the time when postgres did not have reliable compiler and memory barriers. That's not the case anymore, so we can do better. Several of the functions in procarray.c can be bottlenecks, and removal of volatile yields mildly better code. The new state, with explicit memory barriers, is also more correct. The previous use of volatile did not actually deliver sufficient guarantees on weakly ordered machines, in particular the logic in GetNewTransactionId() does not look safe. It seems unlikely to be a problem in practice, but worth fixing. Thomas and I independently wrote a patch for this. Reported-By: Andres Freund and Thomas Munro Author: Andres Freund, with cherrypicked changes from a patch by Thomas Munro Discussion: https://postgr.es/m/20181005172955.wyjb4fzcdzqtaxjq@alap3.anarazel.de https://postgr.es/m/CAEepm=1nff0x=7i3YQO16jLA2qw-F9O39YmUew4oq-xcBQBs0g@mail.gmail.com
* Combine two flag tests in GetSnapshotData().Andres Freund2018-11-09
| | | | | | | | | | | | | | | Previously the code checked PROC_IN_LOGICAL_DECODING and PROC_IN_VACUUM separately. As the relevant variable is marked as volatile, the compiler cannot combine the two tests. As GetSnapshotData() is pretty hot in a number of workloads, it's worthwhile to fix that. It'd also be a good idea to get rid of the volatiles altogether. But for one that's a larger patch, and for another, the code after this change still seems at least as easy to read as before. Author: Andres Freund Discussion: https://postgr.es/m/20181005172955.wyjb4fzcdzqtaxjq@alap3.anarazel.de
* Remove set-but-unused variable.Thomas Munro2018-11-07
| | | | | | | Clean-up for commit c24dcd0c. Reported-by: Andrew Dunstan Discussion: https://postgr.es/m/2d52ff4a-5440-f6f1-7806-423b0e6370cb%402ndQuadrant.com
* Use pg_pread() and pg_pwrite() for data files and WAL.Thomas Munro2018-11-07
| | | | | | | | | | | | | Cut down on system calls by doing random I/O using offset-based OS routines where available. Remove the code for tracking the 'virtual' seek position. The only reason left to call FileSeek() was to get the file's size, so provide a new function FileSize() instead. Author: Oskari Saarenmaa, Thomas Munro Reviewed-by: Thomas Munro, Jesper Pedersen, Tom Lane, Alvaro Herrera Discussion: https://postgr.es/m/CAEepm=02rapCpPR3ZGF2vW=SBHSdFYO_bz_f-wwWJonmA3APgw@mail.gmail.com Discussion: https://postgr.es/m/b8748d39-0b19-0514-a1b9-4e5a28e6a208%40gmail.com Discussion: https://postgr.es/m/a86bd200-ebbe-d829-e3ca-0c4474b2fcb7%40ohmu.fi
* Remove some remaining traces of dsm_resize().Thomas Munro2018-11-06
| | | | | | | A couple of obsolete comments and unreachable blocks remained after commit 3c60d0fa. Discussion: https://postgr.es/m/CAA4eK1%2B%3DyAFUvpFoHXFi_gm8YqmXN-TtkFH%2BVYjvDLS6-SFq-Q%40mail.gmail.com
* Remove dsm_resize() and dsm_remap().Thomas Munro2018-11-06
| | | | | | | | | | These interfaces were never used in core, didn't handle failure of posix_fallocate() correctly and weren't supported on all platforms. We agreed to remove them in 12. Author: Thomas Munro Reported-by: Andres Freund Discussion: https://postgr.es/m/CAA4eK1%2B%3DyAFUvpFoHXFi_gm8YqmXN-TtkFH%2BVYjvDLS6-SFq-Q%40mail.gmail.com
* Fix spelling errors and typos in commentsMagnus Hagander2018-11-02
| | | | Author: Daniel Gustafsson <daniel@yesql.se>
* Correct constness of a few variables.Andres Freund2018-10-15
| | | | | | | | | | | | This allows the compiler / linker to mark affected pages as read-only. There's other cases, but they're a bit more invasive, and should go through some review. These are easy. They were found with objdump -j .data -t src/backend/postgres|awk '{print $4, $5, $6}'|sort -r|less Discussion: https://postgr.es/m/20181015200754.7y7zfuzsoux2c4ya@alap3.anarazel.de
* Avoid duplicate XIDs at recovery when building initial snapshotMichael Paquier2018-10-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On a primary, sets of XLOG_RUNNING_XACTS records are generated on a periodic basis to allow recovery to build the initial state of transactions for a hot standby. The set of transaction IDs is created by scanning all the entries in ProcArray. However it happens that its logic never counted on the fact that two-phase transactions finishing to prepare can put ProcArray in a state where there are two entries with the same transaction ID, one for the initial transaction which gets cleared when prepare finishes, and a second, dummy, entry to track that the transaction is still running after prepare finishes. This way ensures a continuous presence of the transaction so as callers of for example TransactionIdIsInProgress() are always able to see it as alive. So, if a XLOG_RUNNING_XACTS takes a standby snapshot while a two-phase transaction finishes to prepare, the record can finish with duplicated XIDs, which is a state expected by design. If this record gets applied on a standby to initial its recovery state, then it would simply fail, so the odds of facing this failure are very low in practice. It would be tempting to change the generation of XLOG_RUNNING_XACTS so as duplicates are removed on the source, but this requires to hold on ProcArrayLock for longer and this would impact all workloads, particularly those using heavily two-phase transactions. XLOG_RUNNING_XACTS is also actually used only to initialize the standby state at recovery, so instead the solution is taken to discard duplicates when applying the initial snapshot. Diagnosed-by: Konstantin Knizhnik Author: Michael Paquier Discussion: https://postgr.es/m/0c96b653-4696-d4b4-6b5d-78143175d113@postgrespro.ru Backpatch-through: 9.3
* Refactor user-facing SQL functions signalling backendsMichael Paquier2018-10-04
| | | | | | | | | | This moves the system administration functions for signalling backends from backend/utils/adt/misc.c into a separate file dedicated to backend signalling. No new functionality is introduced in this commit. Author: Daniel Gustafsson Reviewed-by: Michael Paquier, Álvaro Herrera Discussion: https://postgr.es/m/C2C7C3EC-CC5F-44B6-9C78-637C88BD7D14@yesql.se
* Add assertions that we hold some relevant lock during relation open.Tom Lane2018-10-01
| | | | | | | | | | | | | | | | | | | | | | | | | Opening a relation with no lock at all is unsafe; there's no guarantee that we'll see a consistent state of the relevant catalog entries. While use of MVCC scans to read the catalogs partially addresses that complaint, it's still possible to switch to a new catalog snapshot partway through loading the relcache entry. Moreover, whether or not you trust the reasoning behind sometimes using less than AccessExclusiveLock for ALTER TABLE, that reasoning is certainly not valid if concurrent users of the table don't hold a lock corresponding to the operation they want to perform. Hence, add some assertion-build-only checks that require any caller of relation_open(x, NoLock) to hold at least AccessShareLock. This isn't a full solution, since we can't verify that the lock level is semantically appropriate for the action --- but it's definitely of some use, because it's already caught two bugs. We can also assert that callers of addRangeTableEntryForRelation() hold at least the lock level specified for the new RTE. Amit Langote and Tom Lane Discussion: https://postgr.es/m/16565.1538327894@sss.pgh.pa.us
* Replace CAS loop with single TAS in ProcArrayGroupClearXid()Alexander Korotkov2018-09-22
| | | | | | | | | Single pg_atomic_exchange_u32() is expected to be faster than loop of pg_atomic_compare_exchange_u32(). Also, it would be consistent with clog group update code. Discussion: https://postgr.es/m/CAPpHfdtxLsC-bqfxFcHswZ91OxXcZVNDBBVfg9tAWU0jvn1tQA%40mail.gmail.com Reviewed-by: Amit Kapila
* Don't ignore locktable-full failures in StandbyAcquireAccessExclusiveLock.Tom Lane2018-09-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 37c54863c removed the code in StandbyAcquireAccessExclusiveLock that checked the return value of LockAcquireExtended. That created a bug, because it's still passing reportMemoryError = false to LockAcquireExtended, meaning that LOCKACQUIRE_NOT_AVAIL will be returned if we're out of shared memory for the lock table. In such a situation, the startup process would believe it had acquired an exclusive lock even though it hadn't, with potentially dire consequences. To fix, just drop the use of reportMemoryError = false, which allows us to simplify the call into a plain LockAcquire(). It's unclear that the locktable-full situation arises often enough that it's worth having a better recovery method than crash-and-restart. (I strongly suspect that the only reason the code path existed at all was that it was relatively simple to do in the pre-37c54863c implementation. But now it's not.) LockAcquireExtended's reportMemoryError parameter is now dead code and could be removed. I refrained from doing so, however, because there was some interest in resurrecting the behavior if we do get reports of locktable-full failures in the field. Also, it seems unwise to remove the parameter concurrently with shipping commit f868a8143, which added a parameter; if there are any third-party callers of LockAcquireExtended, we want them to get a wrong-number-of-parameters compile error rather than a possibly-silent misinterpretation of its last parameter. Back-patch to 9.6 where the bug was introduced. Discussion: https://postgr.es/m/6202.1536359835@sss.pgh.pa.us
* Allow DSM allocation to be interrupted.Thomas Munro2018-09-18
| | | | | | | | | | | | | | | | Chris Travers reported that the startup process can repeatedly try to cancel a backend that is in a posix_fallocate()/EINTR loop and cause it to loop forever. Teach the retry loop to give up if an interrupt is pending. Don't actually check for interrupts in that loop though, because a non-local exit would skip some clean-up code in the caller. Back-patch to 9.4 where DSM was added (and posix_fallocate() was later back-patched). Author: Chris Travers Reviewed-by: Ildar Musin, Murat Kabilov, Oleksii Kliukin Tested-by: Oleksii Kliukin Discussion: https://postgr.es/m/CAN-RpxB-oeZve_J3SM_6%3DHXPmvEG%3DHX%2B9V9pi8g2YR7YW0rBBg%40mail.gmail.com
* Remove duplicated words split across lines in commentsMichael Paquier2018-09-08
| | | | | | | | This has been detected using some interesting tricks with sed, and the method used is mentioned in details in the discussion below. Author: Justin Pryzby Discussion: https://postgr.es/m/20180908013109.GB15350@telsasoft.com
* Fix longstanding recursion hazard in sinval message processing.Tom Lane2018-09-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | LockRelationOid and sibling routines supposed that, if our session already holds the lock they were asked to acquire, they could skip calling AcceptInvalidationMessages on the grounds that we must have already read any remote sinval messages issued against the relation being locked. This is normally true, but there's a critical special case where it's not: processing inside AcceptInvalidationMessages might attempt to access system relations, resulting in a recursive call to acquire a relation lock. Hence, if the outer call had acquired that same system catalog lock, we'd fall through, despite the possibility that there's an as-yet-unread sinval message for that system catalog. This could, for example, result in failure to access a system catalog or index that had just been processed by VACUUM FULL. This is the explanation for buildfarm failures we've been seeing intermittently for the past three months. The bug is far older than that, but commits a54e1f158 et al added a new recursion case within AcceptInvalidationMessages that is apparently easier to hit than any previous case. To fix this, we must not skip calling AcceptInvalidationMessages until we have *finished* a call to it since acquiring a relation lock, not merely acquired the lock. (There's already adequate logic inside AcceptInvalidationMessages to deal with being called recursively.) Fortunately, we can implement that at trivial cost, by adding a flag to LOCALLOCK hashtable entries that tracks whether we know we have completed such a call. There is an API hazard added by this patch for external callers of LockAcquire: if anything is testing for LOCKACQUIRE_ALREADY_HELD, it might be fooled by the new return code LOCKACQUIRE_ALREADY_CLEAR into thinking the lock wasn't already held. This should be a fail-soft condition, though, unless something very bizarre is being done in response to the test. Also, I added an additional output argument to LockAcquireExtended, assuming that that probably isn't called by any outside code given the very limited usefulness of its additional functionality. Back-patch to all supported branches. Discussion: https://postgr.es/m/12259.1532117714@sss.pgh.pa.us
* Avoid using potentially-under-aligned page buffers.Tom Lane2018-09-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | There's a project policy against using plain "char buf[BLCKSZ]" local or static variables as page buffers; preferred style is to palloc or malloc each buffer to ensure it is MAXALIGN'd. However, that policy's been ignored in an increasing number of places. We've apparently got away with it so far, probably because (a) relatively few people use platforms on which misalignment causes core dumps and/or (b) the variables chance to be sufficiently aligned anyway. But this is not something to rely on. Moreover, even if we don't get a core dump, we might be paying a lot of cycles for misaligned accesses. To fix, invent new union types PGAlignedBlock and PGAlignedXLogBlock that the compiler must allocate with sufficient alignment, and use those in place of plain char arrays. I used these types even for variables where there's no risk of a misaligned access, since ensuring proper alignment should make kernel data transfers faster. I also changed some places where we had been palloc'ing short-lived buffers, for coding style uniformity and to save palloc/pfree overhead. Since this seems to be a live portability hazard (despite the lack of field reports), back-patch to all supported versions. Patch by me; thanks to Michael Paquier for review. Discussion: https://postgr.es/m/1535618100.1286.3.camel@credativ.de
* Introduce minimal C99 usage to verify compiler support.Andres Freund2018-08-23
| | | | | | | | | This just converts a few for loops in postgres.c to declare variables in the loop initializer, and uses designated initializers in smgr.c's definition of smgr callbacks. Author: Andres Freund Discussion: https://postgr.es/m/97d4b165-192d-3605-749c-f614a0c4e783@2ndquadrant.com
* Make autovacuum more aggressive to remove orphaned temp tablesMichael Paquier2018-08-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit dafa084, added in 10, made the removal of temporary orphaned tables more aggressive. This commit makes an extra step into the aggressiveness by adding a flag in each backend's MyProc which tracks down any temporary namespace currently in use. The flag is set when the namespace gets created and can be reset if the temporary namespace has been created in a transaction or sub-transaction which is aborted. The flag value assignment is assumed to be atomic, so this can be done in a lock-less fashion like other flags already present in PGPROC like databaseId or backendId, still the fact that the temporary namespace and table created are still locked until the transaction creating those commits acts as a barrier for other backends. This new flag gets used by autovacuum to discard more aggressively orphaned tables by additionally checking for the database a backend is connected to as well as its temporary namespace in-use, removing orphaned temporary relations even if a backend reuses the same slot as one which created temporary relations in a past session. The base idea of this patch comes from Robert Haas, has been written in its first version by Tsunakawa Takayuki, then heavily reviewed by me. Author: Tsunakawa Takayuki Reviewed-by: Michael Paquier, Kyotaro Horiguchi, Andres Freund Discussion: https://postgr.es/m/0A3221C70F24FB45833433255569204D1F8A4DC6@G01JPEXMBYT05 Backpatch: 11-, as PGPROC gains a new flag and we don't want silent ABI breakages on already released versions.
* Fix inadequate buffer locking in FSM and VM page re-initialization.Tom Lane2018-07-13
| | | | | | | | | | | | | | | | | | | When reading an existing FSM or VM page that was found to be corrupt by the buffer manager, the code applied PageInit() to reinitialize the page, but did so without any locking. There is thus a hazard that two backends might concurrently do PageInit, which in itself would still be OK, but the slower one might then zero over subsequent data changes applied by the faster one. Even that is unlikely to be fatal; but it's not desirable, so add locking to prevent it. This does not add any locking overhead in the normal code path where the page is OK. It's not immediately obvious that that's safe, but I believe it is, for reasons explained in the added comments. Problem noted by R P Asim. It's been like this for a long time, so back-patch to all supported branches. Discussion: https://postgr.es/m/CANXE4Te4G0TGq6cr0-TvwP0H4BNiK_-hB5gHe8mF+nz0mcYfMQ@mail.gmail.com
* Reset shmem_exit_inprogress after shmem_exit()Peter Eisentraut2018-07-12
| | | | | | | | | In ad9a274778d2d88c46b90309212b92ee7fdf9afe, shmem_exit_inprogress was introduced. But we need to reset it after shmem_exit(), because unlike the similar proc_exit(), shmem_exit() can also be called for cleanup when the process will not exit. Reported-by: Andrew Gierth <andrew@tao11.riddles.org.uk>
* Fix wrong file path in header commentAlexander Korotkov2018-07-11
| | | | | | Header comment of shm_mq.c was mistakenly specifying path to shm_mq.h. It was introduced in ec9037df. So, theoretically it could be backpatched to 9.4, but it doesn't seem to worth it.
* Use signals for postmaster death on FreeBSD.Thomas Munro2018-07-11
| | | | | | | | | Use FreeBSD 11.2's new support for detecting parent process death to make PostmasterIsAlive() very cheap, as was done for Linux in an earlier commit. Author: Thomas Munro Discussion: https://postgr.es/m/7261eb39-0369-f2f4-1bb5-62f3b6083b5e@iki.fi
* Use signals for postmaster death on Linux.Thomas Munro2018-07-11
| | | | | | | | | | | | Linux provides a way to ask for a signal when your parent process dies. Use that to make PostmasterIsAlive() very cheap. Based on a suggestion from Andres Freund. Author: Thomas Munro, Heikki Linnakangas Reviewed-By: Michael Paquier Discussion: https://postgr.es/m/7261eb39-0369-f2f4-1bb5-62f3b6083b5e%40iki.fi Discussion: https://postgr.es/m/20180411002643.6buofht4ranhei7k%40alap3.anarazel.de
* Remove dynamic_shared_memory_type=nonePeter Eisentraut2018-07-10
| | | | | | | | | PostgreSQL nowadays offers some kind of dynamic shared memory feature on all supported platforms. Having the choice of "none" prevents us from relying on DSM in core features. So this patch removes the choice of "none". Author: Kyotaro Horiguchi <horiguchi.kyotaro@lab.ntt.co.jp>
* Improve the performance of relation deletes during recovery.Fujii Masao2018-07-05
| | | | | | | | | | | | | | | | | | | | | | When multiple relations are deleted at the same transaction, the files of those relations are deleted by one call to smgrdounlinkall(), which leads to scan whole shared_buffers only one time. OTOH, previously, during recovery, smgrdounlink() (not smgrdounlinkall()) was called for each file to delete, which led to scan shared_buffers multiple times. Obviously this could cause to increase the WAL replay time very much especially when shared_buffers was huge. To alleviate this situation, this commit changes the recovery so that it also calls smgrdounlinkall() only one time to delete multiple relation files. This is just fix for oversight of commit 279628a0a7, not new feature. So, per discussion on pgsql-hackers, we concluded to backpatch this to all supported versions. Author: Fujii Masao Reviewed-by: Michael Paquier, Andres Freund, Thomas Munro, Kyotaro Horiguchi, Takayuki Tsunakawa Discussion: https://postgr.es/m/CAHGQGwHVQkdfDqtvGVkty+19cQakAydXn1etGND3X0PHbZ3+6w@mail.gmail.com
* pgindent run prior to branchingAndrew Dunstan2018-06-30
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* Move RecoveryLockList into a hash table.Thomas Munro2018-06-26
| | | | | | | | | | | | | | | | | | Standbys frequently need to release all locks held by a given xid. Instead of searching one big list linearly, let's create one list per xid and put them in a hash table, so we can find what we need in O(1) time. Earlier analysis and a prototype were done by David Rowley, though this isn't his patch. Back-patch all the way. Author: Thomas Munro Diagnosed-by: David Rowley, Andres Freund Reviewed-by: Andres Freund, Tom Lane, Robert Haas Discussion: https://postgr.es/m/CAEepm%3D1mL0KiQ2KJ4yuPpLGX94a4Ns_W6TL4EGRouxWibu56pA%40mail.gmail.com Discussion: https://postgr.es/m/CAKJS1f9vJ841HY%3DwonnLVbfkTWGYWdPN72VMxnArcGCjF3SywA%40mail.gmail.com
* Remove AELs from subxids correctly on standbySimon Riggs2018-06-16
| | | | | | | | | | | | | | | | | | | | Issues relate only to subtransactions that hold AccessExclusiveLocks when replayed on standby. Prior to PG10, aborting subtransactions that held an AccessExclusiveLock failed to release the lock until top level commit or abort. 49bff5300d527 fixed that. However, 49bff5300d527 also introduced a similar bug where subtransaction commit would fail to release an AccessExclusiveLock, leaving the lock to be removed sometimes early and sometimes late. This commit fixes that bug also. Backpatch to PG10 needed. Tested by observation. Note need for multi-node isolationtester to improve test coverage for this and other HS cases. Reported-by: Simon Riggs Author: Simon Riggs
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