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2025-04-19Be more wary of corrupt data in pageinspect's heap_page_items().Tom Lane
The original intent in heap_page_items() was to return nulls, not throw an error or crash, if an item was sufficiently corrupt that we couldn't safely extract data from it. However, commit d6061f83a utterly missed that memo, and not only put in an un-length-checked copy of the tuple's data section, but also managed to break the check on sane nulls-bitmap length. Either mistake could possibly lead to a SIGSEGV crash if the tuple is corrupt. Bug: #18896 Reported-by: Dmitry Kovalenko <d.kovalenko@postgrespro.ru> Author: Dmitry Kovalenko <d.kovalenko@postgrespro.ru> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/18896-add267b8e06663e3@postgresql.org Backpatch-through: 13
2025-01-23Convert macros to static inline functions (htup_details.h, itup.h)Peter Eisentraut
Discussion: https://www.postgresql.org/message-id/flat/5b558da8-99fb-0a99-83dd-f72f05388517@enterprisedb.com
2025-01-01Update copyright for 2025Bruce Momjian
Backpatch-through: 13
2024-12-20Optimize alignment calculations in tuple form/deformDavid Rowley
Here we convert CompactAttribute.attalign from a char, which is directly derived from pg_attribute.attalign into a uint8, which stores the number of bytes to align the column's value by in the tuple. This allows tuple deformation and tuple size calculations to move away from using the inefficient att_align_nominal() macro, which manually checks each TYPALIGN_* char to translate that into the alignment bytes for the given type. Effectively, this commit changes those to TYPEALIGN calls, which are branchless and only perform some simple arithmetic with some bit-twiddling. The removed branches were often mispredicted by CPUs, especially so in real-world tables which often contain a mishmash of different types with different alignment requirements. Author: David Rowley Reviewed-by: Andres Freund, Victor Yegorov Discussion: https://postgr.es/m/CAApHDvrBztXP3yx=NKNmo3xwFAFhEdyPnvrDg3=M0RhDs+4vYw@mail.gmail.com
2024-12-20Introduce CompactAttribute array in TupleDesc, take 2David Rowley
The new compact_attrs array stores a few select fields from FormData_pg_attribute in a more compact way, using only 16 bytes per column instead of the 104 bytes that FormData_pg_attribute uses. Using CompactAttribute allows performance-critical operations such as tuple deformation to be performed without looking at the FormData_pg_attribute element in TupleDesc which means fewer cacheline accesses. For some workloads, tuple deformation can be the most CPU intensive part of processing the query. Some testing with 16 columns on a table where the first column is variable length showed around a 10% increase in transactions per second for an OLAP type query performing aggregation on the 16th column. However, in certain cases, the increases were much higher, up to ~25% on one AMD Zen4 machine. This also makes pg_attribute.attcacheoff redundant. A follow-on commit will remove it, thus shrinking the FormData_pg_attribute struct by 4 bytes. Author: David Rowley Reviewed-by: Andres Freund, Victor Yegorov Discussion: https://postgr.es/m/CAApHDvrBztXP3yx=NKNmo3xwFAFhEdyPnvrDg3=M0RhDs+4vYw@mail.gmail.com
2024-10-28Remove unused #include's from contrib, pl, test .c filesPeter Eisentraut
as determined by IWYU Similar to commit dbbca2cf299, but for contrib, pl, and src/test/. Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org> Discussion: https://www.postgresql.org/message-id/flat/0df1d5b1-8ca8-4f84-93be-121081bde049%40eisentraut.org
2024-09-12Reintroduce support for sequences in pgstattuple and pageinspect.Nathan Bossart
Commit 4b82664156 restricted a number of functions provided by contrib modules to only relations that use the "heap" table access method. Sequences always use this table access method, but they do not advertise as such in the pg_class system catalog, so the aforementioned commit also (presumably unintentionally) removed support for sequences from some of these functions. This commit reintroduces said support for sequences to these functions and adds a couple of relevant tests. Co-authored-by: Ayush Vatsa Reviewed-by: Robert Haas, Michael Paquier, Matthias van de Meent Discussion: https://postgr.es/m/CACX%2BKaP3i%2Bi9tdPLjF5JCHVv93xobEdcd_eB%2B638VDvZ3i%3DcQA%40mail.gmail.com Backpatch-through: 12
2024-01-04Update copyright for 2024Bruce Momjian
Reported-by: Michael Paquier Discussion: https://postgr.es/m/ZZKTDPxBBMt3C0J9@paquier.xyz Backpatch-through: 12
2023-01-02Update copyright for 2023Bruce Momjian
Backpatch-through: 11
2022-09-05Fix incorrect uses of Datum conversion macrosPeter Eisentraut
Since these macros just cast whatever you give them to the designated output type, and many normal uses also cast the output type further, a number of incorrect uses go undiscovered. The fixes in this patch have been discovered by changing these macros to inline functions, which is the subject of a future patch. Reviewed-by: Aleksander Alekseev <aleksander@timescale.com> Discussion: https://www.postgresql.org/message-id/flat/8528fb7e-0aa2-6b54-85fb-0c0886dbd6ed%40enterprisedb.com
2022-07-16Replace many MemSet calls with struct initializationPeter Eisentraut
This replaces all MemSet() calls with struct initialization where that is easily and obviously possible. (For example, some cases have to worry about padding bits, so I left those.) (The same could be done with appropriate memset() calls, but this patch is part of an effort to phase out MemSet(), so it doesn't touch memset() calls.) Reviewed-by: Ranier Vilela <ranier.vf@gmail.com> Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org> Discussion: https://www.postgresql.org/message-id/9847b13c-b785-f4e2-75c3-12ec77a3b05c@enterprisedb.com
2022-07-01Add construct_array_builtin, deconstruct_array_builtinPeter Eisentraut
There were many calls to construct_array() and deconstruct_array() for built-in types, for example, when dealing with system catalog columns. These all hardcoded the type attributes necessary to pass to these functions. To simplify this a bit, add construct_array_builtin(), deconstruct_array_builtin() as wrappers that centralize this hardcoded knowledge. This simplifies many call sites and reduces the amount of hardcoded stuff that is spread around. Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://www.postgresql.org/message-id/flat/2914356f-9e5f-8c59-2995-5997fc48bcba%40enterprisedb.com
2022-01-08Update copyright for 2022Bruce Momjian
Backpatch-through: 10
2021-11-24Fix incorrect format placeholdersPeter Eisentraut
Also choose better types for the underlying variables to make this more consistent.
2021-02-24Fix some typos, grammar and style in docs and commentsMichael Paquier
The portions fixing the documentation are backpatched where needed. Author: Justin Pryzby Discussion: https://postgr.es/m/20210210235557.GQ20012@telsasoft.com backpatch-through: 9.6
2021-01-02Update copyright for 2021Bruce Momjian
Backpatch-through: 9.5
2020-06-29Avoid using %c printf format for potentially non-ASCII characters.Tom Lane
Since %c only passes a C "char" to printf, it's incapable of dealing with multibyte characters. Passing just the first byte of such a character leads to an output string that is visibly not correctly encoded, resulting in undesirable behavior such as encoding conversion failures while sending error messages to clients. We've lived with this issue for a long time because it was inconvenient to avoid in a portable fashion. However, now that we always use our own snprintf code, it's reasonable to use the %.*s format to print just one possibly-multibyte character in a string. (We previously avoided that obvious-looking answer in order to work around glibc's bug #6530, cf commits 54cd4f045 and ed437e2b2.) Hence, run around and fix a bunch of places that used %c to report a character found in a user-supplied string. For simplicity, I did not touch places that were emitting non-user-facing debug messages, or reporting catalog data that should always be ASCII. (It's also unclear how useful this approach could be in frontend code, where it's less certain that we know what encoding we're dealing with.) In passing, improve a couple of poorly-written error messages in pageinspect/heapfuncs.c. This is a longstanding issue, but I'm hesitant to back-patch because of the impact on translatable message strings. In any case this fix would not work reliably before v12. Tom Lane and Quan Zongliang Discussion: https://postgr.es/m/a120087c-4c88-d9d4-1ec5-808d7a7f133d@gmail.com
2020-03-04Introduce macros for typalign and typstorage constants.Tom Lane
Our usual practice for "poor man's enum" catalog columns is to define macros for the possible values and use those, not literal constants, in C code. But for some reason lost in the mists of time, this was never done for typalign/attalign or typstorage/attstorage. It's never too late to make it better though, so let's do that. The reason I got interested in this right now is the need to duplicate some uses of the TYPSTORAGE constants in an upcoming ALTER TYPE patch. But in general, this sort of change aids greppability and readability, so it's a good idea even without any specific motivation. I may have missed a few places that could be converted, and it's even more likely that pending patches will re-introduce some hard-coded references. But that's not fatal --- there's no expectation that we'd actually change any of these values. We can clean up stragglers over time. Discussion: https://postgr.es/m/16457.1583189537@sss.pgh.pa.us
2020-01-30Clean up newlines following left parenthesesAlvaro Herrera
We used to strategically place newlines after some function call left parentheses to make pgindent move the argument list a few chars to the left, so that the whole line would fit under 80 chars. However, pgindent no longer does that, so the newlines just made the code vertically longer for no reason. Remove those newlines, and reflow some of those lines for some extra naturality. Reviewed-by: Michael Paquier, Tom Lane Discussion: https://postgr.es/m/20200129200401.GA6303@alvherre.pgsql
2020-01-30Remove excess parens in ereport() callsAlvaro Herrera
Cosmetic cleanup, not worth backpatching. Discussion: https://postgr.es/m/20200129200401.GA6303@alvherre.pgsql Reviewed-by: Tom Lane, Michael Paquier
2020-01-01Update copyrights for 2020Bruce Momjian
Backpatch-through: update all files in master, backpatch legal files through 9.4
2019-10-24Make the order of the header file includes consistent in contrib modules.Amit Kapila
The basic rule we follow here is to always first include 'postgres.h' or 'postgres_fe.h' whichever is applicable, then system header includes and then Postgres header includes.  In this, we also follow that all the Postgres header includes are in order based on their ASCII value.  We generally follow these rules, but the code has deviated in many places. This commit makes it consistent just for contrib modules. The later commits will enforce similar rules in other parts of code. Author: Vignesh C Reviewed-by: Amit Kapila Discussion: https://postgr.es/m/CALDaNm2Sznv8RR6Ex-iJO6xAdsxgWhCoETkaYX=+9DW3q0QCfA@mail.gmail.com
2019-09-19Redesign pageinspect function printing infomask bitsMichael Paquier
After more discussion, the new function added by ddbd5d8 could have been designed in a better way. Based on an idea from Álvaro, instead of returning one column which includes both the raw and combined flags, use two columns, with one for the raw flags and one for the combined flags. This also takes care of some issues with HEAP_LOCKED_UPGRADED and HEAP_XMAX_IS_LOCKED_ONLY which are not really combined flags as they depend on conditions defined by other raw bits, as mentioned by Amit. While on it, fix an extra issue with combined flags. A combined flag was returned if at least one of its bits was set, but all its bits need to be set to include it in the result. Author: Michael Paquier Reviewed-by: Álvaro Herrera, Amit Kapila Discussion: https://postgr.es/m/20190913114950.GA3824@alvherre.pgsql
2019-09-12Add to pageinspect function to make t_infomask/t_infomask2 human-readableMichael Paquier
Flags of t_infomask and t_infomask2 for each tuple are already included in the information returned by heap_page_items as integers, and we lacked a way to make that information human-readable. Per discussion, the function includes an option which controls if combined flags should be decomposed or not. The default is false, to not decompose combined flags. The module is bumped to version 1.8. Author: Craig Ringer, Sawada Masahiko Reviewed-by: Peter Geoghegan, Robert Haas, Álvaro Herrera, Moon Insung, Amit Kapila, Michael Paquier, Tomas Vondra Discussion: https://postgr.es/m/CAMsr+YEY7jeaXOb+oX+RhDyOFuTMdmHjGsBxL=igCm03J0go9Q@mail.gmail.com
2019-04-01Only allow heap in a number of contrib modules.Andres Freund
Contrib modules pgrowlocks, pgstattuple and some functionality in pageinspect currently only supports the heap table AM. As they are all concerned with low-level details that aren't reasonably exposed via tableam, error out if invoked on a non heap relation. Author: Andres Freund Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
2019-01-21Replace heapam.h includes with {table, relation}.h where applicable.Andres Freund
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
2019-01-15Don't include heapam.h from others headers.Andres Freund
heapam.h previously was included in a number of widely used headers (e.g. execnodes.h, indirectly in executor.h, ...). That's problematic on its own, as heapam.h contains a lot of low-level details that don't need to be exposed that widely, but becomes more problematic with the upcoming introduction of pluggable table storage - it seems inappropriate for heapam.h to be included that widely afterwards. heapam.h was largely only included in other headers to get the HeapScanDesc typedef (which was defined in heapam.h, even though HeapScanDescData is defined in relscan.h). The better solution here seems to be to just use the underlying struct (forward declared where necessary). Similar for BulkInsertState. Another problem was that LockTupleMode was used in executor.h - parts of the file tried to cope without heapam.h, but due to the fact that it indirectly included it, several subsequent violations of that goal were not not noticed. We could just reuse the approach of declaring parameters as int, but it seems nicer to move LockTupleMode to lockoptions.h - that's not a perfect location, but also doesn't seem bad. As a number of files relied on implicitly included heapam.h, a significant number of files grew an explicit include. It's quite probably that a few external projects will need to do the same. Author: Andres Freund Reviewed-By: Alvaro Herrera Discussion: https://postgr.es/m/20190114000701.y4ttcb74jpskkcfb@alap3.anarazel.de
2019-01-02Update copyright for 2019Bruce Momjian
Backpatch-through: certain files through 9.4
2018-11-21Remove WITH OIDS support, change oid catalog column visibility.Andres Freund
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
2018-10-01Fix tuple_data_split() to not open a relation without any lock.Tom Lane
contrib/pageinspect's tuple_data_split() function thought it could get away with opening the referenced relation with NoLock. In practice there's no guarantee that the current session holds any lock on that rel (even if we just read a page from it), so that this is unsafe. Switch to using AccessShareLock. Also, postpone closing the relation, so that we needn't copy its tupdesc. Also, fix unsafe use of att_isnull() for attributes past the end of the tuple. Per testing with a patch that complains if we open a relation without holding any lock on it. I don't plan to back-patch that patch, but we should close the holes it identifies in all supported branches. Discussion: https://postgr.es/m/2038.1538335244@sss.pgh.pa.us
2018-01-04Fix incorrect computations of length of null bitmap in pageinspect.Tom Lane
Instead of using our standard macro for this calculation, this code did it itself ... and got it wrong, leading to incorrect display of the null bitmap in some cases. Noted and fixed by Maksim Milyutin. In passing, remove a uselessly duplicative error check. Errors were introduced in commit d6061f83a; back-patch to 9.6 where that came in. Maksim Milyutin, reviewed by Andrey Borodin Discussion: https://postgr.es/m/ec295792-a69f-350f-6287-25a20e8f31d5@gmail.com
2018-01-03Update copyright for 2018Bruce Momjian
Backpatch-through: certain files through 9.3
2017-08-20Change tupledesc->attrs[n] to TupleDescAttr(tupledesc, n).Andres Freund
This is a mechanical change in preparation for a later commit that will change the layout of TupleDesc. Introducing a macro to abstract the details of where attributes are stored will allow us to change that in separate step and revise it in future. Author: Thomas Munro, editorialized by Andres Freund Reviewed-By: Andres Freund Discussion: https://postgr.es/m/CAEepm=0ZtQ-SpsgCyzzYpsXS6e=kZWqk3g5Ygn3MDV7A8dabUA@mail.gmail.com
2017-06-21Phase 3 of pgindent updates.Tom Lane
Don't move parenthesized lines to the left, even if that means they flow past the right margin. By default, BSD indent lines up statement continuation lines that are within parentheses so that they start just to the right of the preceding left parenthesis. However, traditionally, if that resulted in the continuation line extending to the right of the desired right margin, then indent would push it left just far enough to not overrun the margin, if it could do so without making the continuation line start to the left of the current statement indent. That makes for a weird mix of indentations unless one has been completely rigid about never violating the 80-column limit. This behavior has been pretty universally panned by Postgres developers. Hence, disable it with indent's new -lpl switch, so that parenthesized lines are always lined up with the preceding left paren. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-02-03In pageinspect/hashfuncs.c, avoid crashes on alignment-picky machines.Tom Lane
On machines with MAXALIGN = 8, the payload of a bytea is not maxaligned, since it will start 4 bytes into a palloc'd value. On alignment-picky hardware, this will cause failures in accesses to 8-byte-wide values within the page. We already encountered this problem when we introduced GIN index inspection functions, and fixed it in commit 84ad68d64. Make use of the same function for hash indexes. A small difficulty is that up to now contrib/pageinspect has not shared any functions at all across files. To support that, introduce a common header file "pageinspect.h" for the module. Also, move get_page_from_raw() out of ginfuncs.c, where it didn't especially belong, and put it in rawpage.c which seems a more natural home. Per buildfarm. Discussion: https://postgr.es/m/17311.1486134714@sss.pgh.pa.us
2017-01-03Update copyright via script for 2017Bruce Momjian
2016-10-26Fix typo in comment.Heikki Linnakangas
Daniel Gustafsson
2016-06-09pgindent run for 9.6Robert Haas
2016-05-03Tweak a few more things in preparation for upcoming pgindent run.Robert Haas
These adjustments adjust code and comments in minor ways to prevent pgindent from mangling them. Among other things, I tried to avoid situations where pgindent would emit "a +b" instead of "a + b", and I tried to avoid having it break up inline comments across multiple lines.
2016-04-08Replace printf format %i by %dPeter Eisentraut
see also ce8d7bb6440710058503d213b2aafcdf56a5b481
2016-04-08Fix printf formatPeter Eisentraut
2016-01-02Update copyright for 2016Bruce Momjian
Backpatch certain files through 9.1
2015-11-25Improve pageinspect moduleTeodor Sigaev
Now pageinspect can show data stored in the heap tuple. Nikolay Shaplov
2015-02-21Use FLEXIBLE_ARRAY_MEMBER for HeapTupleHeaderData.t_bits[].Tom Lane
This requires changing quite a few places that were depending on sizeof(HeapTupleHeaderData), but it seems for the best. Michael Paquier, some adjustments by me
2015-01-06Update copyright for 2015Bruce Momjian
Backpatch certain files through 9.0
2014-04-18Create function prototype as part of PG_FUNCTION_INFO_V1 macroPeter Eisentraut
Because of gcc -Wmissing-prototypes, all functions in dynamically loadable modules must have a separate prototype declaration. This is meant to detect global functions that are not declared in header files, but in cases where the function is called via dfmgr, this is redundant. Besides filling up space with boilerplate, this is a frequent source of compiler warnings in extension modules. We can fix that by creating the function prototype as part of the PG_FUNCTION_INFO_V1 macro, which such modules have to use anyway. That makes the code of modules cleaner, because there is one less place where the entry points have to be listed, and creates an additional check that functions have the right prototype. Remove now redundant prototypes from contrib and other modules.
2014-01-07Update copyright for 2014Bruce Momjian
Update all files in head, and files COPYRIGHT and legal.sgml in all back branches.
2013-12-22Change the way we mark tuples as frozen.Robert Haas
Instead of changing the tuple xmin to FrozenTransactionId, the combination of HEAP_XMIN_COMMITTED and HEAP_XMIN_INVALID, which were previously never set together, is now defined as HEAP_XMIN_FROZEN. A variety of previous proposals to freeze tuples opportunistically before vacuum_freeze_min_age is reached have foundered on the objection that replacing xmin by FrozenTransactionId might hinder debugging efforts when things in this area go awry; this patch is intended to solve that problem by keeping the XID around (but largely ignoring the value to which it is set). Third-party code that checks for HEAP_XMIN_INVALID on tuples where HEAP_XMIN_COMMITTED might be set will be broken by this change. To fix, use the new accessor macros in htup_details.h rather than consulting the bits directly. HeapTupleHeaderGetXmin has been modified to return FrozenTransactionId when the infomask bits indicate that the tuple is frozen; use HeapTupleHeaderGetRawXmin when you already know that the tuple isn't marked commited or frozen, or want the raw value anyway. We currently do this in routines that display the xmin for user consumption, in tqual.c where it's known to be safe and important for the avoidance of extra cycles, and in the function-caching code for various procedural languages, which shouldn't invalidate the cache just because the tuple gets frozen. Robert Haas and Andres Freund
2013-01-23Improve concurrency of foreign key lockingAlvaro Herrera
This patch introduces two additional lock modes for tuples: "SELECT FOR KEY SHARE" and "SELECT FOR NO KEY UPDATE". These don't block each other, in contrast with already existing "SELECT FOR SHARE" and "SELECT FOR UPDATE". UPDATE commands that do not modify the values stored in the columns that are part of the key of the tuple now grab a SELECT FOR NO KEY UPDATE lock on the tuple, allowing them to proceed concurrently with tuple locks of the FOR KEY SHARE variety. Foreign key triggers now use FOR KEY SHARE instead of FOR SHARE; this means the concurrency improvement applies to them, which is the whole point of this patch. The added tuple lock semantics require some rejiggering of the multixact module, so that the locking level that each transaction is holding can be stored alongside its Xid. Also, multixacts now need to persist across server restarts and crashes, because they can now represent not only tuple locks, but also tuple updates. This means we need more careful tracking of lifetime of pg_multixact SLRU files; since they now persist longer, we require more infrastructure to figure out when they can be removed. pg_upgrade also needs to be careful to copy pg_multixact files over from the old server to the new, or at least part of multixact.c state, depending on the versions of the old and new servers. Tuple time qualification rules (HeapTupleSatisfies routines) need to be careful not to consider tuples with the "is multi" infomask bit set as being only locked; they might need to look up MultiXact values (i.e. possibly do pg_multixact I/O) to find out the Xid that updated a tuple, whereas they previously were assured to only use information readily available from the tuple header. This is considered acceptable, because the extra I/O would involve cases that would previously cause some commands to block waiting for concurrent transactions to finish. Another important change is the fact that locking tuples that have previously been updated causes the future versions to be marked as locked, too; this is essential for correctness of foreign key checks. This causes additional WAL-logging, also (there was previously a single WAL record for a locked tuple; now there are as many as updated copies of the tuple there exist.) With all this in place, contention related to tuples being checked by foreign key rules should be much reduced. As a bonus, the old behavior that a subtransaction grabbing a stronger tuple lock than the parent (sub)transaction held on a given tuple and later aborting caused the weaker lock to be lost, has been fixed. Many new spec files were added for isolation tester framework, to ensure overall behavior is sane. There's probably room for several more tests. There were several reviewers of this patch; in particular, Noah Misch and Andres Freund spent considerable time in it. Original idea for the patch came from Simon Riggs, after a problem report by Joel Jacobson. Most code is from me, with contributions from Marti Raudsepp, Alexander Shulgin, Noah Misch and Andres Freund. This patch was discussed in several pgsql-hackers threads; the most important start at the following message-ids: AANLkTimo9XVcEzfiBR-ut3KVNDkjm2Vxh+t8kAmWjPuv@mail.gmail.com 1290721684-sup-3951@alvh.no-ip.org 1294953201-sup-2099@alvh.no-ip.org 1320343602-sup-2290@alvh.no-ip.org 1339690386-sup-8927@alvh.no-ip.org 4FE5FF020200002500048A3D@gw.wicourts.gov 4FEAB90A0200002500048B7D@gw.wicourts.gov
2013-01-01Update copyrights for 2013Bruce Momjian
Fully update git head, and update back branches in ./COPYRIGHT and legal.sgml files.