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path: root/src/backend/executor/nodeAgg.c
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* Remove unused #include's from backend .c filesPeter Eisentraut2024-03-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | as determined by include-what-you-use (IWYU) While IWYU also suggests to *add* a bunch of #include's (which is its main purpose), this patch does not do that. In some cases, a more specific #include replaces another less specific one. Some manual adjustments of the automatic result: - IWYU currently doesn't know about includes that provide global variable declarations (like -Wmissing-variable-declarations), so those includes are being kept manually. - All includes for port(ability) headers are being kept for now, to play it safe. - No changes of catalog/pg_foo.h to catalog/pg_foo_d.h, to keep the patch from exploding in size. Note that this patch touches just *.c files, so nothing declared in header files changes in hidden ways. As a small example, in src/backend/access/transam/rmgr.c, some IWYU pragma annotations are added to handle a special case there. Discussion: https://www.postgresql.org/message-id/flat/af837490-6b2f-46df-ba05-37ea6a6653fc%40eisentraut.org
* Update copyright for 2024Bruce Momjian2024-01-03
| | | | | | | | Reported-by: Michael Paquier Discussion: https://postgr.es/m/ZZKTDPxBBMt3C0J9@paquier.xyz Backpatch-through: 12
* Remove obsolete executor cleanup codeAmit Langote2023-09-28
| | | | | | | | | | | | | | | | | | | This commit removes unnecessary ExecExprFreeContext() calls in ExecEnd* routines because the actual cleanup is managed by FreeExecutorState(). With no callers remaining for ExecExprFreeContext(), this commit also removes the function. This commit also drops redundant ExecClearTuple() calls, because ExecResetTupleTable() in ExecEndPlan() already takes care of resetting and dropping all TupleTableSlots initialized with ExecInitScanTupleSlot() and ExecInitExtraTupleSlot(). After these modifications, the ExecEnd*() routines for ValuesScan, NamedTuplestoreScan, and WorkTableScan became redundant. So, this commit removes them. Reviewed-by: Robert Haas Discussion: https://postgr.es/m/CA+HiwqFGkMSge6TgC9KQzde0ohpAycLQuV7ooitEEpbKB0O_mg@mail.gmail.com
* Pre-beta mechanical code beautification.Tom Lane2023-05-19
| | | | | | | | | | | | | | | Run pgindent, pgperltidy, and reformat-dat-files. This set of diffs is a bit larger than typical. We've updated to pg_bsd_indent 2.1.2, which properly indents variable declarations that have multi-line initialization expressions (the continuation lines are now indented one tab stop). We've also updated to perltidy version 20230309 and changed some of its settings, which reduces its desire to add whitespace to lines to make assignments etc. line up. Going forward, that should make for fewer random-seeming changes to existing code. Discussion: https://postgr.es/m/20230428092545.qfb3y5wcu4cm75ur@alvherre.pgsql
* Mark internal messages as no longer translatableAlvaro Herrera2023-05-16
| | | | | | | | | | | The problem that these messages protect against can only occur because a corrupted hash spill file was written, i.e., a Postgres bug. There's no reason to have them as translatable. Backpatch to 15, where these messages were changed by commit c4649cce39a4. Reviewed-by: Daniel Gustafsson <daniel@yesql.se> Discussion: https://postgr.es/m/20230510175407.dwa5v477pw62ikyx@alvherre.pgsql
* Fix typos in commentsMichael Paquier2023-05-02
| | | | | | | | | The changes done in this commit impact comments with no direct user-visible changes, with fixes for incorrect function, variable or structure names. Author: Alexander Lakhin Discussion: https://postgr.es/m/e8c38840-596a-83d6-bd8d-cebc51111572@gmail.com
* Rename ExecAggTransReparent, and improve its documentation.Tom Lane2023-04-24
| | | | | | | | | | | | | The name of this function suggests that it ought to reparent R/W expanded objects to be children of the persistent aggcontext, instead of copying them. In fact it does no such thing, and if you try to make it do so you will see multiple regression failures. Rename it to the less-misleading ExecAggCopyTransValue, and add commentary about why that attractive-sounding optimization won't work. Also adjust comments at call sites, some of which were describing logic that has since been moved into ExecAggCopyTransValue. Discussion: https://postgr.es/m/3004282.1681930251@sss.pgh.pa.us
* Fix various typos and incorrect/outdated name referencesDavid Rowley2023-04-19
| | | | | Author: Alexander Lakhin Discussion: https://postgr.es/m/699beab4-a6ca-92c9-f152-f559caf6dc25@gmail.com
* Ensure result of an aggregate's finalfunc is made read-only.Tom Lane2023-04-16
| | | | | | | | | | | | | | | The finalfunc might return a read-write expanded object. If we de-duplicate multiple call sites for the aggregate, any function(s) receiving the aggregate result earlier could alter or destroy the value that reaches the ones called later. This is a brown-paper-bag bug in commit 42b746d4c, because we actually considered the need for read-only-ness but failed to realize that it applied to the case with a finalfunc as well as the case without. Per report from Justin Pryzby. New error in HEAD, no need for back-patch. Discussion: https://postgr.es/m/ZDm5TuKsh3tzoEjz@telsasoft.com
* Mop up some undue familiarity with the innards of Bitmapsets.Tom Lane2023-03-02
| | | | | | | | | | | | | | | | | | | | | nodeAppend.c used non-nullness of appendstate->as_valid_subplans as a state flag to indicate whether it'd done ExecFindMatchingSubPlans (or some sufficient approximation to that). This was pretty questionable even in the beginning, since it wouldn't really work right if there are no valid subplans. It got more questionable after commit 27e1f1456 added logic that could reduce as_valid_subplans to an empty set: at that point we were depending on unspecified behavior of bms_del_members, namely that it'd not return an empty set as NULL. It's about to start doing that, which breaks this logic entirely. Hence, add a separate boolean flag to signal whether as_valid_subplans has been computed. Also fix a previously-cosmetic bug in nodeAgg.c, wherein it ignored the return value of bms_del_member instead of updating its pointer. Patch by me; thanks to Nathan Bossart and Richard Guo for review. Discussion: https://postgr.es/m/1159933.1677621588@sss.pgh.pa.us
* Remove bms_first_member().Tom Lane2023-03-02
| | | | | | | | | | | | | | This function has been semi-deprecated ever since we invented bms_next_member(). Its habit of scribbling on the input bitmapset isn't great, plus for sufficiently large bitmapsets it would take O(N^2) time to complete a loop. Now we have the additional problem that reducing the input to empty while leaving it still accessible would violate a planned invariant. So let's just get rid of it, after updating the few extant callers to use bms_next_member(). Patch by me; thanks to Nathan Bossart and Richard Guo for review. Discussion: https://postgr.es/m/1159933.1677621588@sss.pgh.pa.us
* Remove redundant grouping and DISTINCT columns.Tom Lane2023-01-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Avoid explicitly grouping by columns that we know are redundant for sorting, for example we need group by only one of x and y in SELECT ... WHERE x = y GROUP BY x, y This comes up more often than you might think, as shown by the changes in the regression tests. It's nearly free to detect too, since we are just piggybacking on the existing logic that detects redundant pathkeys. (In some of the existing plans that change, it's visible that a sort step preceding the grouping step already didn't bother to sort by the redundant column, making the old plan a bit silly-looking.) To do this, build processed_groupClause and processed_distinctClause lists that omit any provably-redundant sort items, and consult those not the originals where relevant. This means that within the planner, one should usually consult root->processed_groupClause or root->processed_distinctClause if one wants to know which columns are to be grouped on; but to check whether grouping or distinct-ing is happening at all, check non-NIL-ness of parse->groupClause or parse->distinctClause. This is comparable to longstanding rules about handling the HAVING clause, so I don't think it'll be a huge maintenance problem. nodeAgg.c also needs minor mods, because it's now possible to generate AGG_PLAIN and AGG_SORTED Agg nodes with zero grouping columns. Patch by me; thanks to Richard Guo and David Rowley for review. Discussion: https://postgr.es/m/185315.1672179489@sss.pgh.pa.us
* Avoid reference to nonexistent array element in ExecInitAgg().Tom Lane2023-01-02
| | | | | | | | | | | | | | | | When considering an empty grouping set, we fetched phasedata->eqfunctions[-1]. Because the eqfunctions array is palloc'd, that would always be an aset pointer in released versions, and thus the code accidentally failed to malfunction (since it would do nothing unless it found a null pointer). Nonetheless this seems like trouble waiting to happen, so add a check for length == 0. It's depressing that our valgrind testing did not catch this. Maybe we should reconsider the choice to not mark that word NOACCESS? Richard Guo Discussion: https://postgr.es/m/CAMbWs4-vZuuPOZsKOYnSAaPYGKhmacxhki+vpOKk0O7rymccXQ@mail.gmail.com
* Update copyright for 2023Bruce Momjian2023-01-02
| | | | Backpatch-through: 11
* Remove unnecessary castsPeter Eisentraut2022-12-30
| | | | | | | | Some code carefully cast all data buffer arguments for data write and read function calls to void *, even though the respective arguments are already void *. Remove this unnecessary clutter. Discussion: https://www.postgresql.org/message-id/flat/11dda853-bb5b-59ba-a746-e168b1ce4bdb%40enterprisedb.com
* Refactor aclcheck functionsPeter Eisentraut2022-11-13
| | | | | | | | | | | | | | | | | | Instead of dozens of mostly-duplicate pg_foo_aclcheck() functions, write one common function object_aclcheck() that can handle almost all of them. We already have all the information we need, such as which system catalog corresponds to which catalog table and which column is the ACL column. There are a few pg_foo_aclcheck() that don't work via the generic function and have special APIs, so those stay as is. I also changed most pg_foo_aclmask() functions to static functions, since they are not used outside of aclchk.c. Reviewed-by: Corey Huinker <corey.huinker@gmail.com> Reviewed-by: Antonin Houska <ah@cybertec.at> Discussion: https://www.postgresql.org/message-id/flat/95c30f96-4060-2f48-98b5-a4392d3b6066@enterprisedb.com
* Allow nodeSort to perform Datum sorts for byref typesDavid Rowley2022-10-28
| | | | | | | | | | | | | | | | | | | | | | | | Here we add a new 'copy' parameter to tuplesort_getdatum so that we can instruct the function not to datumCopy() byref Datums before returning. Similar to 91e9e89dc, this can provide significant performance improvements in nodeSort when sorting by a single byref column and the sort's targetlist contains only that column. This allows us to re-enable Datum sorts for byref types which was disabled in 3a5817695 due to a reported memory leak. Additionally, here we slightly optimize DISTINCT aggregates so that we no longer perform any datumCopy() when we find the current value not to be distinct from the previous value. Previously the code would always take a copy of the most recent Datum and pfree the previous value, even when the values were the same. Testing shows a small but noticeable performance increase when aggregate transitions are skipped due to the current transition value being the same as the prior one. Author: David Rowley Discussion: https://postgr.es/m/CAApHDvqS6wC5U==k9Hd26E4EQXH3QR67-T4=Q1rQ36NGvjfVSg@mail.gmail.com Discussion: https://postgr.es/m/CAApHDvqHonfe9G1cVaKeHbDx70R_zCrM3qP2AGXpGrieSKGnhA@mail.gmail.com
* Remove uses of MemoryContextContains in nodeAgg.c and nodeWindowAgg.c.Tom Lane2022-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | MemoryContextContains is no longer reliable in the wake of c6e0fe1f2, so we need to get rid of these uses. It appears that there's no really good reason to force the result of an aggregate's finalfn or serialfn to be allocated in the per-tuple context. The only other plausible case is that the result points to or into the aggregate's transition value, and that's fine because it will last as long as we need it to. (This conclusion depends on the assumption that finalfns are not allowed to scribble on the transition value, but we've long required that.) So we can just drop the MemoryContextContains plus datumCopy business, although we do need to take care to not return a read-write pointer when the transition value is an expanded datum. Likewise, we don't really need to force the result of a window function to be in the output context. In this case, the plausible alternative is that it's pointing into the temporary tuple slot used by WinGetFuncArgInPartition or WinGetFuncArgInFrame (since those functions could return such a pointer, which might become the window function's result). That will hold still for long enough, unless there is another window function using the same WindowObject. I'm content to always perform a datumCopy when there's more than one such function. On net, these changes should provide small speed improvements as well as removing problematic code. Tom Lane and David Rowley Discussion: https://postgr.es/m/1913788.1664898906@sss.pgh.pa.us
* Rename shadowed local variablesDavid Rowley2022-10-05
| | | | | | | | | | | | In a similar effort to f01592f91, here we mostly rename shadowed local variables to remove the warnings produced when compiling with -Wshadow=compatible-local. This fixes 63 warnings and leaves just 5. Author: Justin Pryzby, David Rowley Reviewed-by: Justin Pryzby Discussion https://postgr.es/m/20220817145434.GC26426%40telsasoft.com
* Harmonize parameter names in storage and AM code.Peter Geoghegan2022-09-19
| | | | | | | | | | | | | | | Make sure that function declarations use names that exactly match the corresponding names from function definitions in storage, catalog, access method, executor, and logical replication code, as well as in miscellaneous utility/library code. Like other recent commits that cleaned up function parameter names, this commit was written with help from clang-tidy. Later commits will do the same for other parts of the codebase. Author: Peter Geoghegan <pg@bowt.ie> Reviewed-By: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com
* Further reduce warnings with -Wshadow=compatible-localDavid Rowley2022-08-24
| | | | | | | | | | | | | | | | | | | | | | | In a similar effort to f01592f91, here we're targetting fixing the warnings that -Wshadow=compatible-local produces that we can fix by moving a variable to an inner scope to stop that variable from being shadowed by another variable declared somewhere later in the function. All of the warnings being fixed here are changing the scope of variables which are being used as an iterator for a "for" loop. In each instance, the fix happens to be changing the for loop to use the C99 type initialization. Much of this code likely pre-dates our use of C99. Reducing the scope of the outer scoped variable seems like the safest way to fix these. Renaming seems more likely to risk patches using the wrong variable. Reducing the scope is more likely to result in a compilation failure after applying some future patch rather than introducing bugs with it. By my count, this takes the warning count from 129 down to 114. Author: Justin Pryzby Discussion: https://postgr.es/m/CAApHDvrwLGBP%2BYw9vriayyf%3DXR4uPWP5jr6cQhP9au_kaDUhbA%40mail.gmail.com
* Improve performance of ORDER BY / DISTINCT aggregatesDavid Rowley2022-08-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ORDER BY / DISTINCT aggreagtes have, since implemented in Postgres, been executed by always performing a sort in nodeAgg.c to sort the tuples in the current group into the correct order before calling the transition function on the sorted tuples. This was not great as often there might be an index that could have provided pre-sorted input and allowed the transition functions to be called as the rows come in, rather than having to store them in a tuplestore in order to sort them once all the tuples for the group have arrived. Here we change the planner so it requests a path with a sort order which supports the most amount of ORDER BY / DISTINCT aggregate functions and add new code to the executor to allow it to support the processing of ORDER BY / DISTINCT aggregates where the tuples are already sorted in the correct order. Since there can be many ORDER BY / DISTINCT aggregates in any given query level, it's very possible that we can't find an order that suits all of these aggregates. The sort order that the planner chooses is simply the one that suits the most aggregate functions. We take the most strictly sorted variation of each order and see how many aggregate functions can use that, then we try again with the order of the remaining aggregates to see if another order would suit more aggregate functions. For example: SELECT agg(a ORDER BY a),agg2(a ORDER BY a,b) ... would request the sort order to be {a, b} because {a} is a subset of the sort order of {a,b}, but; SELECT agg(a ORDER BY a),agg2(a ORDER BY c) ... would just pick a plan ordered by {a} (we give precedence to aggregates which are earlier in the targetlist). SELECT agg(a ORDER BY a),agg2(a ORDER BY b),agg3(a ORDER BY b) ... would choose to order by {b} since two aggregates suit that vs just one that requires input ordered by {a}. Author: David Rowley Reviewed-by: Ronan Dunklau, James Coleman, Ranier Vilela, Richard Guo, Tom Lane Discussion: https://postgr.es/m/CAApHDvpHzfo92%3DR4W0%2BxVua3BUYCKMckWAmo-2t_KiXN-wYH%3Dw%40mail.gmail.com
* Remove stray references to lefttree/righttree in the executor.Tom Lane2022-07-07
| | | | | | | | | | | | | The general convention in the executor is to refer to child plans and planstates via the outerPlan[State] and innerPlan[State] macros, but a few places didn't do it like that. For consistency and readability, convert all the stragglers to use the macros. (See also commit 40f42d2a3, which did some similar cleanup a few years ago, but missed these cases.) Richard Guo Discussion: https://postgr.es/m/CAMbWs4-vYhh1xsa_veah4PUed2Xq=Ed_YH3=Mqt5A3Y=EgfCEg@mail.gmail.com
* Clean up newlines following left parenthesesAlvaro Herrera2022-05-13
| | | | Like commit c9d297751959.
* Remove extraneous blank lines before block-closing bracesAlvaro Herrera2022-04-13
| | | | | | | | | These are useless and distracting. We wouldn't have written the code with them to begin with, so there's no reason to keep them. Author: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20220411020336.GB26620@telsasoft.com Discussion: https://postgr.es/m/attachment/133167/0016-Extraneous-blank-lines.patch
* Adjust tuplesort API to have bitwise option flagsDavid Rowley2022-04-04
| | | | | | | | | | | | | | | | This replaces the bool flag for randomAccess. An upcoming patch requires adding another option, so instead of breaking the API for that, then breaking it again one day if we add more options, let's just break it once. Any boolean options we add in the future will just make use of an unused bit in the flags. Any extensions making use of tuplesorts will need to update their code to pass TUPLESORT_RANDOMACCESS instead of true for randomAccess. TUPLESORT_NONE can be used for a set of empty options. Author: David Rowley Reviewed-by: Justin Pryzby Discussion: https://postgr.es/m/CAApHDvoH4ASzsAOyHcxkuY01Qf%2B%2B8JJ0paw%2B03dk%2BW25tQEcNQ%40mail.gmail.com
* Update copyright for 2022Bruce Momjian2022-01-07
| | | | Backpatch-through: 10
* Avoid some other O(N^2) hazards in list manipulation.Tom Lane2021-11-01
| | | | | | | | | | | | In the same spirit as 6301c3ada, fix some more places where we were using list_delete_first() in a loop and thereby risking O(N^2) behavior. It's not clear that the lists manipulated in these spots can get long enough to be really problematic ... but it's not clear that they can't, either, and the fixes are simple enough. As before, back-patch to v13. Discussion: https://postgr.es/m/CD2F0E7F-9822-45EC-A411-AE56F14DEA9F@amazon.com
* Refactor LogicalTapeSet/LogicalTape interface.Heikki Linnakangas2021-10-18
| | | | | | | | | | | | All the tape functions, like LogicalTapeRead and LogicalTapeWrite, now take a LogicalTape as argument, instead of LogicalTapeSet+tape number. You can create any number of LogicalTapes in a single LogicalTapeSet, and you don't need to decide the number upfront, when you create the tape set. This makes the tape management in hash agg spilling in nodeAgg.c simpler. Discussion: https://www.postgresql.org/message-id/420a0ec7-602c-d406-1e75-1ef7ddc58d83%40iki.fi Reviewed-by: Peter Geoghegan, Zhihong Yu, John Naylor
* Get rid of artificial restriction on hash table sizes on Windows.Tom Lane2021-07-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The point of introducing the hash_mem_multiplier GUC was to let users reproduce the old behavior of hash aggregation, i.e. that it could use more than work_mem at need. However, the implementation failed to get the job done on Win64, where work_mem is clamped to 2GB to protect various places that calculate memory sizes using "long int". As written, the same clamp was applied to hash_mem. This resulted in severe performance regressions for queries requiring a bit more than 2GB for hash aggregation, as they now spill to disk and there's no way to stop that. Getting rid of the work_mem restriction seems like a good idea, but it's a big job and could not conceivably be back-patched. However, there's only a fairly small number of places that are concerned with the hash_mem value, and it turns out to be possible to remove the restriction there without too much code churn or any ABI breaks. So, let's do that for now to fix the regression, and leave the larger task for another day. This patch does introduce a bit more infrastructure that should help with the larger task, namely pg_bitutils.h support for working with size_t values. Per gripe from Laurent Hasson. Back-patch to v13 where the behavior change came in. Discussion: https://postgr.es/m/997817.1627074924@sss.pgh.pa.us Discussion: https://postgr.es/m/MN2PR15MB25601E80A9B6D1BA6F592B1985E39@MN2PR15MB2560.namprd15.prod.outlook.com
* Cleanup some aggregate code in the executorDavid Rowley2021-07-04
| | | | | | | | | | | | | | | | | | | | | Here we alter the code that calls build_pertrans_for_aggref() so that the function no longer needs to special-case whether it's dealing with an aggtransfn or an aggcombinefn. This allows us to reuse the build_aggregate_transfn_expr() function and just get rid of the build_aggregate_combinefn_expr() completely. All of the special case code that was in build_pertrans_for_aggref() has been moved up to the calling functions. This saves about a dozen lines of code in nodeAgg.c and a few dozen more in parse_agg.c Also, rename a few variables in nodeAgg.c to try to make it more clear that we're working with either a aggtransfn or an aggcombinefn. Some of the old names would have you believe that we were always working with an aggtransfn. Discussion: https://postgr.es/m/CAApHDvptMQ9FmF0D67zC_w88yVnoNVR2+kkOQGUrCmdxWxLULQ@mail.gmail.com
* Initial pgindent and pgperltidy run for v14.Tom Lane2021-05-12
| | | | | | | | Also "make reformat-dat-files". The only change worthy of note is that pgindent messed up the formatting of launcher.c's struct LogicalRepWorkerId, which led me to notice that that struct wasn't used at all anymore, so I just took it out.
* Fix some typos, grammar and style in docs and commentsMichael Paquier2021-02-24
| | | | | | | | 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
* Fix bug in HashAgg's selective-column-spilling logic.Tom Lane2021-02-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 230230223 taught nodeAgg.c that, when spilling tuples from memory in an oversized hash aggregation, it only needed to spill input columns referenced in the node's tlist and quals. Unfortunately, that's wrong: we also have to save the grouping columns. The error is masked in common cases because the grouping columns also appear in the tlist, but that's not necessarily true. The main category of plans where it's not true seem to come from semijoins ("WHERE outercol IN (SELECT innercol FROM innertable)") where the innercol needs an implicit promotion to make it comparable to the outercol. The grouping column will be "innercol::promotedtype", but that expression appears nowhere in the Agg node's own tlist and quals; only the bare "innercol" is found in the tlist. I spent quite a bit of time looking for a suitable regression test case for this, without much success. If the number of distinct values of the innercol is large enough to make spilling happen, the planner tends to prefer a non-HashAgg plan, at least for problem sizes that are reasonable to use in the regression tests. So, no new regression test. However, this patch does demonstrably fix the originally-reported test case. Per report from s.p.e (at) gmx-topmail.de. Backpatch to v13 where the troublesome code came in. Discussion: https://postgr.es/m/trinity-1c565d44-159f-488b-a518-caf13883134f-1611835701633@3c-app-gmx-bap78
* Update copyright for 2021Bruce Momjian2021-01-02
| | | | Backpatch-through: 9.5
* Fix bug #16784 in Disk-based Hash Aggregation.Jeff Davis2020-12-26
| | | | | | | | | | | | | | | | | Before processing tuples, agg_refill_hash_table() was setting all pergroup pointers to NULL to signal to advance_aggregates() that it should not attempt to advance groups that had spilled. The problem was that it also set the pergroups for sorted grouping sets to NULL, which caused rescanning to fail. Instead, change agg_refill_hash_table() to only set the pergroups for hashed grouping sets to NULL; and when compiling the expression, pass doSort=false. Reported-by: Alexander Lakhin Discussion: https://postgr.es/m/16784-7ff169bf2c3d1588%40postgresql.org Backpatch-through: 13
* Move per-agg and per-trans duplicate finding to the planner.Heikki Linnakangas2020-11-24
| | | | | | | | | | This has the advantage that the cost estimates for aggregates can count the number of calls to transition and final functions correctly. Bump catalog version, because views can contain Aggrefs. Reviewed-by: Andres Freund Discussion: https://www.postgresql.org/message-id/b2e3536b-1dbc-8303-c97e-89cb0b4a9a48%40iki.fi
* Skip allocating hash table in EXPLAIN-only mode.Heikki Linnakangas2020-11-18
| | | | | Author: Alexey Bashtanov Discussion: https://www.postgresql.org/message-id/36823f65-050d-ae24-aa4d-a37726998240%40imap.cc
* Remove useless entries for aggregate functions from fmgrtab.c.Tom Lane2020-11-04
| | | | | | | | | | | | | | | | | | | | | | | Gen_fmgrtab.pl treated aggregate functions the same as other built-in functions, which is wasteful because there is no real need to have entries for them in the fmgr_builtins[] table. Suppressing those entries saves about 3KB in the compiled table on my machine; which is not a lot but it's not nothing either, considering that that table is pretty "hot". The only outside code change needed is that ExecInitWindowAgg() can't be allowed to call fmgr_info_cxt() on a plain aggregate function. But that saves a few cycles anyway. Having done that, the aggregate_dummy() function is unreferenced and might as well be dropped. Using "aggregate_dummy" as the prosrc value for an aggregate is now just a documentation convention not something that matters. There was some discussion of using NULL instead to save a few bytes in pg_proc, but we'd have to remove prosrc's BKI_FORCE_NOT_NULL marking which doesn't seem a great idea. Anyway, it's possible there's client-side code that expects to see "aggregate_dummy" there, so I'm loath to change it without a strong reason. Discussion: https://postgr.es/m/533989.1604263665@sss.pgh.pa.us
* Change LogicalTapeSetBlocks() to use nBlocksWritten.Jeff Davis2020-09-15
| | | | | | | | | | | | | Previously, it was based on nBlocksAllocated to account for tapes with open write buffers that may not have made it to the BufFile yet. That was unnecessary, because callers do not need to get the number of blocks while a tape has an open write buffer; and it also conflicted with the preallocation logic added for HashAgg. Reviewed-by: Peter Geoghegan Discussion: https://postgr.es/m/ce5af05900fdbd0e9185747825a7423c48501964.camel@j-davis.com Backpatch-through: 13
* HashAgg: release write buffers sooner by rewinding tape.Jeff Davis2020-09-15
| | | | | | | | | | This was an oversight. The purpose of 7fdd919ae7 was to avoid keeping tape buffers around unnecessisarily, but HashAgg didn't rewind early enough. Reviewed-by: Peter Geoghegan Discussion: https://postgr.es/m/1fb1151c2cddf8747d14e0532da283c3f97e2685.camel@j-davis.com Backpatch-through: 13
* logtape.c: do not preallocate for tapes when sortingJeff Davis2020-09-11
| | | | | | | | | | | The preallocation logic is only useful for HashAgg, so disable it when sorting. Also, adjust an out-of-date comment. Reviewed-by: Peter Geoghegan Discussion: https://postgr.es/m/CAH2-Wzn_o7tE2+hRVvwSFghRb75AJ5g-nqGzDUqLYMexjOAe=g@mail.gmail.com Backpatch-through: 13
* Add hash_mem_multiplier GUC.Peter Geoghegan2020-07-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a GUC that acts as a multiplier on work_mem. It gets applied when sizing executor node hash tables that were previously size constrained using work_mem alone. The new GUC can be used to preferentially give hash-based nodes more memory than the generic work_mem limit. It is intended to enable admin tuning of the executor's memory usage. Overall system throughput and system responsiveness can be improved by giving hash-based executor nodes more memory (especially over sort-based alternatives, which are often much less sensitive to being memory constrained). The default value for hash_mem_multiplier is 1.0, which is also the minimum valid value. This means that hash-based nodes continue to apply work_mem in the traditional way by default. hash_mem_multiplier is generally useful. However, it is being added now due to concerns about hash aggregate performance stability for users that upgrade to Postgres 13 (which added disk-based hash aggregation in commit 1f39bce0). While the old hash aggregate behavior risked out-of-memory errors, it is nevertheless likely that many users actually benefited. Hash agg's previous indifference to work_mem during query execution was not just faster; it also accidentally made aggregation resilient to grouping estimate problems (at least in cases where this didn't create destabilizing memory pressure). hash_mem_multiplier can provide a certain kind of continuity with the behavior of Postgres 12 hash aggregates in cases where the planner incorrectly estimates that all groups (plus related allocations) will fit in work_mem/hash_mem. This seems necessary because hash-based aggregation is usually much slower when only a small fraction of all groups can fit. Even when it isn't possible to totally avoid hash aggregates that spill, giving hash aggregation more memory will reliably improve performance (the same cannot be said for external sort operations, which appear to be almost unaffected by memory availability provided it's at least possible to get a single merge pass). The PostgreSQL 13 release notes should advise users that increasing hash_mem_multiplier can help with performance regressions associated with hash aggregation. That can be taken care of by a later commit. Author: Peter Geoghegan Reviewed-By: Álvaro Herrera, Jeff Davis Discussion: https://postgr.es/m/20200625203629.7m6yvut7eqblgmfo@alap3.anarazel.de Discussion: https://postgr.es/m/CAH2-WzmD%2Bi1pG6rc1%2BCjc4V6EaFJ_qSuKCCHVnH%3DoruqD-zqow%40mail.gmail.com Backpatch: 13-, where disk-based hash aggregation was introduced.
* HashAgg: use better cardinality estimate for recursive spilling.Jeff Davis2020-07-28
| | | | | | | | | | | | | | | | Use HyperLogLog to estimate the group cardinality in a spilled partition. This estimate is used to choose the number of partitions if we recurse. The previous behavior was to use the number of tuples in a spilled partition as the estimate for the number of groups, which lead to overpartitioning. That could cause the number of batches to be much higher than expected (with each batch being very small), which made it harder to interpret EXPLAIN ANALYZE results. Reviewed-by: Peter Geoghegan Discussion: https://postgr.es/m/a856635f9284bc36f7a77d02f47bbb6aaf7b59b3.camel@j-davis.com Backpatch-through: 13
* Rename another "hash_mem" local variable.Peter Geoghegan2020-07-28
| | | | | | Missed by my commit 564ce621. Backpatch: 13-, where disk-based hash aggregation was introduced.
* Make EXPLAIN ANALYZE of HashAgg more similar to Hash JoinDavid Rowley2020-07-29
| | | | | | | | | | | | | | | | | | | | | | | | | There were various unnecessary differences between Hash Agg's EXPLAIN ANALYZE output and Hash Join's. Here we modify the Hash Agg output so that it's better aligned to Hash Join's. The following changes have been made: 1. Start batches counter at 1 instead of 0. 2. Always display the "Batches" property, even when we didn't spill to disk. 3. Use the text "Batches" instead of "HashAgg Batches" for text format. 4. Use the text "Memory Usage" instead of "Peak Memory Usage" for text format. 5. Include "Batches" before "Memory Usage" in both text and non-text formats. In passing also modify the "Planned Partitions" property so that we show it regardless of if the value is 0 or not for non-text EXPLAIN formats. This was pointed out by Justin Pryzby and probably should have been part of 40efbf870. Reviewed-by: Justin Pryzby, Jeff Davis Discussion: https://postgr.es/m/CAApHDvrshRnA6C0VFnu7Fb9TVvgGo80PUMm5+2DiaS1gEkPvtw@mail.gmail.com Backpatch-through: 13, where HashAgg batching was introduced
* Fix LookupTupleHashEntryHash() pipeline-stall issue.Jeff Davis2020-07-26
| | | | | | | | Refactor hash lookups in nodeAgg.c to improve performance. Author: Andres Freund and Jeff Davis Discussion: https://postgr.es/m/20200612213715.op4ye4q7gktqvpuo%40alap3.anarazel.de Backpatch-through: 13
* Rename "hash_mem" local variable.Peter Geoghegan2020-07-17
| | | | | | The term "hash_mem" will take on new significance when pending work to add a new hash_mem_multiplier GUC is committed. Rename a local variable that happens to have been called hash_mem now to avoid confusion.
* HashAgg: before spilling tuples, set unneeded columns to NULL.Jeff Davis2020-07-12
| | | | | | | | | This is a replacement for 4cad2534. Instead of projecting all tuples going into a HashAgg, only remove unnecessary attributes when actually spilling. This avoids the regression for the in-memory case. Discussion: https://postgr.es/m/a2fb7dfeb4f50aa0a123e42151ee3013933cb802.camel%40j-davis.com Backpatch-through: 13
* Fix EXPLAIN ANALYZE for parallel HashAgg plansDavid Rowley2020-06-19
| | | | | | | | | | | | | | | Since 1f39bce02, HashAgg nodes have had the ability to spill to disk when memory consumption exceeds work_mem. That commit added new properties to EXPLAIN ANALYZE to show the maximum memory usage and disk usage, however, it didn't quite go as far as showing that information for parallel workers. Since workers may have experienced something very different from the main process, we should show this information per worker, as is done in Sort. Reviewed-by: Justin Pryzby Reviewed-by: Jeff Davis Discussion: https://postgr.es/m/CAApHDvpEKbfZa18mM1TD7qV6PG+w97pwCWq5tVD0dX7e11gRJw@mail.gmail.com Backpatch-through: 13, where the hashagg spilling code was added.
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-23 14:52:35 +0000