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* Use the correct tuplestore read pointer in a NamedTuplestoreScan.Tom Lane2018-02-27
| | | | | | | | | | | Tom Kazimiers reported that transition tables don't work correctly when they are scanned by more than one executor node. That's because commit 18ce3a4ab allocated separate read pointers for each executor node, as it must, but failed to make them active at the appropriate times. Repair. Thomas Munro Discussion: https://postgr.es/m/20180224034748.bixarv6632vbxgeb%40dewberry.localdomain
* Fix misbehavior of CTE-used-in-a-subplan during EPQ rechecks.Tom Lane2018-02-19
| | | | | | | | | | | | | | | | | | An updating query that reads a CTE within an InitPlan or SubPlan could get incorrect results if it updates rows that are concurrently being modified. This is caused by CteScanNext supposing that nothing inside its recursive ExecProcNode call could change which read pointer is selected in the CTE's shared tuplestore. While that's normally true because of scoping considerations, it can break down if an EPQ plan tree gets built during the call, because EvalPlanQualStart builds execution trees for all subplans whether they're going to be used during the recheck or not. And it seems like a pretty shaky assumption anyway, so let's just reselect our own read pointer here. Per bug #14870 from Andrei Gorita. This has been broken since CTEs were implemented, so back-patch to all supported branches. Discussion: https://postgr.es/m/20171024155358.1471.82377@wrigleys.postgresql.org
* Improve bit perturbation in TupleHashTableHash.Andres Freund2018-01-29
| | | | | | | | | | | | | | | | The changes in b81b5a96f424531b97cdd1dba97d9d1b9c9d372e did not fully address the issue, because the bit-mixing of the IV into the final hash-key didn't prevent clustering in the input-data survive in the output data. This didn't cause a lot of problems because of the additional growth conditions added d4c62a6b623d6eef88218158e9fa3cf974c6c7e5. But as we want to rein those in due to explosive growth in some edges, this needs to be fixed. Author: Andres Freund Discussion: https://postgr.es/m/20171127185700.1470.20362@wrigleys.postgresql.org Backpatch: 10, where simplehash was introduced
* Avoid crash during EvalPlanQual recheck of an inner indexscan.Tom Lane2018-01-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 09529a70b changed nodeIndexscan.c and nodeIndexonlyscan.c to postpone initialization of the indexscan proper until the first tuple fetch. It overlooked the question of mark/restore behavior, which means that if some caller attempts to mark the scan before the first tuple fetch, you get a null pointer dereference. The only existing user of mark/restore is nodeMergejoin.c, which (somewhat accidentally) will never attempt to set a mark before the first inner tuple unless the inner child node is a Material node. Hence the case can't arise normally, so it seems sufficient to document the assumption at both ends. However, during an EvalPlanQual recheck, ExecScanFetch doesn't call IndexNext but just returns the jammed-in test tuple. Therefore, if we're doing a recheck in a plan tree with a mergejoin with inner indexscan, it's possible to reach ExecIndexMarkPos with iss_ScanDesc still null, as reported by Guo Xiang Tan in bug #15032. Really, when there's a test tuple supplied during an EPQ recheck, touching the index at all is the wrong thing: rather, the behavior of mark/restore ought to amount to saving and restoring the es_epqScanDone flag. We can avoid finding a place to actually save the flag, for the moment, because given the assumption that no caller will set a mark before fetching a tuple, es_epqScanDone must always be set by the time we try to mark. So the actual behavior change required is just to not reach the index access if a test tuple is supplied. The set of plan node types that need to consider this issue are those that support EPQ test tuples (i.e., call ExecScan()) and also support mark/restore; which is to say, IndexScan, IndexOnlyScan, and perhaps CustomScan. It's tempting to try to fix the problem in one place by teaching ExecMarkPos() itself about EPQ; but ExecMarkPos supports some plan types that aren't Scans, and also it seems risky to make assumptions about what a CustomScan wants to do here. Also, the most likely future change here is to decide that we do need to support marks placed before the first tuple, which would require additional work in IndexScan and IndexOnlyScan in any case. Hence, fix the EPQ issue in nodeIndexscan.c and nodeIndexonlyscan.c, accepting the small amount of code duplicated thereby, and leave it to CustomScan providers to fix this bug if they have it. Back-patch to v10 where commit 09529a70b came in. In earlier branches, the index_markpos() call is a waste of cycles when EPQ is active, but no more than that, so it doesn't seem appropriate to back-patch further. Discussion: https://postgr.es/m/20180126074932.3098.97815@wrigleys.postgresql.org
* When passing query strings to workers, pass the terminating \0.Robert Haas2017-12-20
| | | | | | | | | Otherwise, when the query string is read, we might trailing garbage beyond the end, unless there happens to be a \0 there by good luck. Report and patch by Thomas Munro. Reviewed by Rafia Sabih. Discussion: http://postgr.es/m/CAEepm=2SJs7X+_vx8QoDu8d1SMEOxtLhxxLNzZun_BvNkuNhrw@mail.gmail.com
* Try again to fix accumulation of parallel worker instrumentation.Robert Haas2017-12-19
| | | | | | | | | | | | | | | | | When a Gather or Gather Merge node is started and stopped multiple times, accumulate instrumentation data only once, at the end, instead of after each execution, to avoid recording inflated totals. Commit 778e78ae9fa51e58f41cbdc72b293291d02d8984, the previous attempt at a fix, instead reset the state after every execution, which worked for the general instrumentation data but had problems for the additional instrumentation specific to Sort and Hash nodes. Report by hubert depesz lubaczewski. Analysis and fix by Amit Kapila, following a design proposal from Thomas Munro, with a comment tweak by me. Discussion: http://postgr.es/m/20171127175631.GA405@depesz.com
* Fix crashes on plans with multiple Gather (Merge) nodes.Robert Haas2017-12-18
| | | | | | | | | | | | | | | | es_query_dsa turns out to be broken by design, because it supposes that there is only one DSA for the whole query, whereas there is actually one per Gather (Merge) node. For now, work around that problem by setting and clearing the pointer around the sections of code that might need it. It's probably a better idea to get rid of es_query_dsa altogether in favor of having each node keep track individually of which DSA is relevant, but that seems like more than we would want to back-patch. Thomas Munro, reviewed and tested by Andreas Seltenreich, Amit Kapila, and by me. Discussion: http://postgr.es/m/CAEepm=1U6as=brnVvMNixEV2tpi8NuyQoTmO8Qef0-VV+=7MDA@mail.gmail.com
* Revert "Fix accumulation of parallel worker instrumentation."Robert Haas2017-12-13
| | | | | | | This reverts commit 778e78ae9fa51e58f41cbdc72b293291d02d8984. Per further discussion, that doesn't seem to be the best possible fix. Discussion: http://postgr.es/m/CAA4eK1LW2aFKzY3=vwvc=t-juzPPVWP2uT1bpx_MeyEqnM+p8g@mail.gmail.com
* Fix commentPeter Eisentraut2017-12-11
| | | | Reported-by: Noah Misch <noah@leadboat.com>
* Fix corner-case coredump in _SPI_error_callback().Tom Lane2017-12-11
| | | | | | | | | | | I noticed that _SPI_execute_plan initially sets spierrcontext.arg = NULL, and only fills it in some time later. If an error were to happen in between, _SPI_error_callback would try to dereference the null pointer. This is unlikely --- there's not much between those points except push-snapshot calls --- but it's clearly not impossible. Tweak the callback to do nothing if the pointer isn't set yet. It's been like this for awhile, so back-patch to all supported branches.
* Fix accumulation of parallel worker instrumentation.Robert Haas2017-12-05
| | | | | | | | | | | | | When a Gather or Gather Merge node is started and stopped multiple times, the old code wouldn't reset the shared state between executions, potentially resulting in dramatically inflated instrumentation data for nodes beneath it. (The per-worker instrumentation ended up OK, I think, but the overall totals were inflated.) Report by hubert depesz lubaczewski. Analysis and fix by Amit Kapila, reviewed and tweaked a bit by me. Discussion: http://postgr.es/m/20171127175631.GA405@depesz.com
* Teach bitmap heap scan to cope with absence of a DSA.Robert Haas2017-11-28
| | | | | | | | | | | | If we have a plan that uses parallelism but are unable to execute it using parallelism, for example due to a lack of available DSM segments, then the EState's es_query_dsa will be NULL. Parallel bitmap heap scan needs to fall back to a non-parallel scan in such cases. Patch by me, reviewed by Dilip Kumar Discussion: http://postgr.es/m/CAEepm=0kADK5inNf_KuemjX=HQ=PuTP0DykM--fO5jS5ePVFEA@mail.gmail.com
* Fix creation of resjunk tlist entries for inherited mixed UPDATE/DELETE.Tom Lane2017-11-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | rewriteTargetListUD's processing is dependent on the relkind of the query's target table. That was fine at the time it was made to act that way, even for queries on inheritance trees, because all tables in an inheritance tree would necessarily be plain tables. However, the 9.5 feature addition allowing some members of an inheritance tree to be foreign tables broke the assumption that rewriteTargetListUD's output tlist could be applied to all child tables with nothing more than column-number mapping. This led to visible failures if foreign child tables had row-level triggers, and would also break in cases where child tables belonged to FDWs that used methods other than CTID for row identification. To fix, delay running rewriteTargetListUD until after the planner has expanded inheritance, so that it is applied separately to the (already mapped) tlist for each child table. We can conveniently call it from preprocess_targetlist. Refactor associated code slightly to avoid the need to heap_open the target relation multiple times during preprocess_targetlist. (The APIs remain a bit ugly, particularly around the point of which steps scribble on parse->targetList and which don't. But avoiding such scribbling would require a change in FDW callback APIs, which is more pain than it's worth.) Also fix ExecModifyTable to ensure that "tupleid" is reset to NULL when we transition from rows providing a CTID to rows that don't. (That's really an independent bug, but it manifests in much the same cases.) Add a regression test checking one manifestation of this problem, which was that row-level triggers on a foreign child table did not work right. Back-patch to 9.5 where the problem was introduced. Etsuro Fujita, reviewed by Ildus Kurbangaliev and Ashutosh Bapat Discussion: https://postgr.es/m/20170514150525.0346ba72@postgrespro.ru
* Repair failure with SubPlans in multi-row VALUES lists.Tom Lane2017-11-25
| | | | | | | | | | | | | | | | | | | | | | | When nodeValuesscan.c was written, it was impossible to have a SubPlan in VALUES --- any sub-SELECT there would have to be uncorrelated and thereby would produce an InitPlan instead. We therefore took a shortcut in the logic that throws away a ValuesScan's per-row expression evaluation data structures. This was broken by the introduction of LATERAL however; a sub-SELECT containing a lateral reference produces a correlated SubPlan. The cleanest fix for this would be to give up the optimization of discarding the expression eval state. But that still seems pretty unappetizing for long VALUES lists. It seems to work to just prevent the subexpressions from hooking into the ValuesScan node's subPlan list, so let's do that and see how well it works. (If this breaks, due to additional connections between the subexpressions and the outer query structures, we might consider compromises like throwing away data only for VALUES rows not containing SubPlans.) Per bug #14924 from Christian Duta. Back-patch to 9.3 where LATERAL was introduced. Discussion: https://postgr.es/m/20171124120836.1463.5310@wrigleys.postgresql.org
* Fix handling of NULLs returned by aggregate combine functions.Andres Freund2017-11-23
| | | | | | | | | | | | | | | | | | | | | | | When strict aggregate combine functions, used in multi-stage/parallel aggregation, returned NULL, we didn't check for that, invoking the combine function with NULL the next round, despite it being strict. The equivalent code invoking normal transition functions has a check for that situation, which did not get copied in a7de3dc5c346. Fix the bug by adding the equivalent check. Based on a quick look I could not find any strict combine functions in core actually returning NULL, and it doesn't seem very likely external users have done so. So this isn't likely to have caused issues in practice. Add tests verifying transition / combine functions returning NULL is tested. Reported-By: Andres Freund Author: Andres Freund Discussion: https://postgr.es/m/20171121033642.7xvmjqrl4jdaaat3@alap3.anarazel.de Backpatch: 9.6, where parallel aggregation was introduced
* Revert bogus fixes of HOT-freezing bugAlvaro Herrera2017-11-02
| | | | | | | | | | It turns out we misdiagnosed what the real problem was. Revert the previous changes, because they may have worse consequences going forward. A better fix is forthcoming. The simplistic test case is kept, though disabled. Discussion: https://postgr.es/m/20171102112019.33wb7g5wp4zpjelu@alap3.anarazel.de
* Fix mistaken failure to allow parallelism in corner case.Robert Haas2017-10-27
| | | | | | | | | | | | | | | If we try to run a parallel plan in serial mode because, for example, it's going to be scanned via a cursor, but for some reason we're already in parallel mode (for example because an outer query is running in parallel), we'd incorrectly try to launch workers. Fix by adding a flag to the EState, so that we can be certain that ExecutePlan() and ExecGather()/ExecGatherMerge() will have the same idea about whether we are executing serially or in parallel. Report and fix by Amit Kapila with help from Kuntal Ghosh. A few tweaks by me. Discussion: http://postgr.es/m/CAA4eK1+_BuZrmVCeua5Eqnm4Co9DAXdM5HPAOE2J19ePbR912Q@mail.gmail.com
* Repair breakage of aggregate FILTER option.Tom Lane2017-10-16
| | | | | | | | | | | | | | | | | An aggregate's input expression(s) are not supposed to be evaluated at all for a row where its FILTER test fails ... but commit 8ed3f11bb overlooked that requirement. Reshuffle so that aggregates having a filter clause evaluate their arguments separately from those without. This still gets the benefit of doing only one ExecProject in the common case of multiple Aggrefs, none of which have filters. While at it, arrange for filter clauses to be included in the common ExecProject evaluation, thus perhaps buying a little bit even when there are filters. Back-patch to v10 where the bug was introduced. Discussion: https://postgr.es/m/30065.1508161354@sss.pgh.pa.us
* Restore nodeAgg.c's ability to check for improperly-nested aggregates.Tom Lane2017-10-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | While poking around in the aggregate logic, I noticed that commit 8ed3f11bb broke the logic in nodeAgg.c that purports to detect nested aggregates, by moving initialization of regular aggregate argument expressions out of the code segment that checks for that. You could argue that this check is unnecessary, but it's not much code so I'm inclined to keep it as a backstop against parser and planner bugs. However, there's certainly zero value in checking only some of the subexpressions. We can make the check complete again, and as a bonus make it a good deal more bulletproof against future mistakes of the same ilk, by moving it out to the outermost level of ExecInitAgg. This means we need to check only once per Agg node not once per aggregate, which also seems like a good thing --- if the check does find something wrong, it's not urgent that we report it before the plan node initialization finishes. Since this requires remembering the original length of the aggs list, I deleted a long-obsolete stanza that changed numaggs from 0 to 1. That's so old it predates our decision that palloc(0) is a valid operation, in (digs...) 2004, see commit 24a1e20f1. In passing improve a few comments. Back-patch to v10, just in case.
* Fix AggGetAggref() so it won't lie to aggregate final functions.Tom Lane2017-10-12
| | | | | | | | | | | | | | | | | | | | | | If we merge the transition calculations for two different aggregates, it's reasonable to assume that the transition function should not care which of those Aggref structs it gets from AggGetAggref(). It is not reasonable to make the same assumption about an aggregate final function, however. Commit 804163bc2 broke this, as it will pass whichever Aggref was first associated with the transition state in both cases. This doesn't create an observable bug so far as the core system is concerned, because the only existing uses of AggGetAggref() are in ordered-set aggregates that happen to not pay attention to anything but the input properties of the Aggref; and besides that, we disabled sharing of transition calculations for OSAs yesterday. Nonetheless, if some third-party code were using AggGetAggref() in a normal aggregate, they would be entitled to call this a bug. Hence, back-patch the fix to 9.6 where the problem was introduced. In passing, improve some of the comments about transition state sharing. Discussion: https://postgr.es/m/CAB4ELO5RZhOamuT9Xsf72ozbenDLLXZKSk07FiSVsuJNZB861A@mail.gmail.com
* Fix logical replication to fire BEFORE ROW DELETE triggers.Robert Haas2017-10-12
| | | | | | | | | | Before, that would fail to happen unless a BEFORE ROW UPDATE trigger was also present. Noted by me while reviewing a patch from Masahiko Sawada, who also wrote this patch. Reviewed by Petr Jelinek. Discussion: http://postgr.es/m/CA+TgmobAZvCxduG8y_mQKBK7nz-vhbdLvjM354KEFozpuzMN5A@mail.gmail.com
* Prevent sharing transition states between ordered-set aggregates.Tom Lane2017-10-11
| | | | | | | | | | | | | | | | | | | | | | | | This ought to work, but the built-in OSAs are not capable of coping, because their final-functions destructively modify their transition state (specifically, the contained tuplesort object). That was fine when those functions were written, but commit 804163bc2 moved the goalposts without telling orderedsetaggs.c. We should fix the built-in OSAs to support this, but it will take a little work, especially if we don't want to sacrifice performance in the normal non-shared-state case. Given that it took a year after 9.6 release for anyone to notice this bug, we should not prioritize sharable-state over nonsharable-state performance. And a proper fix is likely to be more complicated than we'd want to back-patch, too. Therefore, let's just put in this stop-gap patch to prevent nodeAgg.c from choosing to use shared state for OSAs. We can revert it in HEAD when we get a better fix. Report from Lukas Eder, diagnosis by me, patch by David Rowley. Back-patch to 9.6 where the problem was introduced. Discussion: https://postgr.es/m/CAB4ELO5RZhOamuT9Xsf72ozbenDLLXZKSk07FiSVsuJNZB861A@mail.gmail.com
* Fix mistakes in comments.Robert Haas2017-10-11
| | | | | | Masahiko Sawada Discussion: http://postgr.es/m/CAD21AoBsfYsMHD6_SL9iN3n_Foaa+oPbL5jG55DxU1ChaujqwQ@mail.gmail.com
* Fix crash when logical decoding is invoked from a PL function.Tom Lane2017-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The logical decoding functions do BeginInternalSubTransaction and RollbackAndReleaseCurrentSubTransaction to clean up after themselves. It turns out that AtEOSubXact_SPI has an unrecognized assumption that we always need to cancel the active SPI operation in the SPI context that surrounds the subtransaction (if there is one). That's true when the RollbackAndReleaseCurrentSubTransaction call is coming from the SPI-using function itself, but not when it's happening inside some unrelated function invoked by a SPI query. In practice the affected callers are the various PLs. To fix, record the current subtransaction ID when we begin a SPI operation, and clean up only if that ID is the subtransaction being canceled. Also, remove AtEOSubXact_SPI's assertion that it must have cleaned up the surrounding SPI context's active tuptable. That's proven wrong by the same test case. Also clarify (or, if you prefer, reinterpret) the calling conventions for _SPI_begin_call and _SPI_end_call. The memory context cleanup in the latter means that these have always had the flavor of a matched resource-management pair, but they weren't documented that way before. Per report from Ben Chobot. Back-patch to 9.4 where logical decoding came in. In principle, the SPI changes should go all the way back, since the problem dates back to commit 7ec1c5a86. But given the lack of field complaints it seems few people are using internal subtransactions in this way. So I don't feel a need to take any risks in 9.2/9.3. Discussion: https://postgr.es/m/73FBA179-C68C-4540-9473-71E865408B15@silentmedia.com
* Fix intra-query memory leakage in nodeProjectSet.c.Tom Lane2017-10-06
| | | | | | | | | | | | Both ExecMakeFunctionResultSet() and evaluation of simple expressions need to be done in the per-tuple memory context, not per-query, else we leak data until end of query. This is a consideration that was missed while refactoring code in the ProjectSet patch (note that in pre-v10, ExecMakeFunctionResult is called in the per-tuple context). Per bug #14843 from Ben M. Diagnosed independently by Andres and myself. Discussion: https://postgr.es/m/20171005230321.28561.15927@wrigleys.postgresql.org
* Fix traversal of half-frozen update chainsAlvaro Herrera2017-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When some tuple versions in an update chain are frozen due to them being older than freeze_min_age, the xmax/xmin trail can become broken. This breaks HOT (and probably other things). A subsequent VACUUM can break things in more serious ways, such as leaving orphan heap-only tuples whose root HOT redirect items were removed. This can be seen because index creation (or REINDEX) complain like ERROR: XX000: failed to find parent tuple for heap-only tuple at (0,7) in table "t" Because of relfrozenxid contraints, we cannot avoid the freezing of the early tuples, so we must cope with the results: whenever we see an Xmin of FrozenTransactionId, consider it a match for whatever the previous Xmax value was. This problem seems to have appeared in 9.3 with multixact changes, though strictly speaking it seems unrelated. Since 9.4 we have commit 37484ad2a "Change the way we mark tuples as frozen", so the fix is simple: just compare the raw Xmin (still stored in the tuple header, since freezing merely set an infomask bit) to the Xmax. But in 9.3 we rewrite the Xmin value to FrozenTransactionId, so the original value is lost and we have nothing to compare the Xmax with. To cope with that case we need to compare the Xmin with FrozenXid, assume it's a match, and hope for the best. Sadly, since you can pg_upgrade a 9.3 instance containing half-frozen pages to newer releases, we need to keep the old check in newer versions too, which seems a bit brittle; I hope we can somehow get rid of that. I didn't optimize the new function for performance. The new coding is probably a bit slower than before, since there is a function call rather than a straight comparison, but I'd rather have it work correctly than be fast but wrong. This is a followup after 20b655224249 fixed a few related problems. Apparently, in 9.6 and up there are more ways to get into trouble, but in 9.3 - 9.5 I cannot reproduce a problem anymore with this patch, so there must be a separate bug. Reported-by: Peter Geoghegan Diagnosed-by: Peter Geoghegan, Michael Paquier, Daniel Wood, Yi Wen Wong, Álvaro Discussion: https://postgr.es/m/CAH2-Wznm4rCrhFAiwKPWTpEw2bXDtgROZK7jWWGucXeH3D1fmA@mail.gmail.com
* Fix SQL-spec incompatibilities in new transition table feature.Tom Lane2017-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The standard says that all changes of the same kind (insert, update, or delete) caused in one table by a single SQL statement should be reported in a single transition table; and by that, they mean to include foreign key enforcement actions cascading from the statement's direct effects. It's also reasonable to conclude that if the standard had wCTEs, they would say that effects of wCTEs applying to the same table as each other or the outer statement should be merged into one transition table. We weren't doing it like that. Hence, arrange to merge tuples from multiple update actions into a single transition table as much as we can. There is a problem, which is that if the firing of FK enforcement triggers and after-row triggers with transition tables is interspersed, we might need to report more tuples after some triggers have already seen the transition table. It seems like a bad idea for the transition table to be mutable between trigger calls. There's no good way around this without a major redesign of the FK logic, so for now, resolve it by opening a new transition table each time this happens. Also, ensure that AFTER STATEMENT triggers fire just once per statement, or once per transition table when we're forced to make more than one. Previous versions of Postgres have allowed each FK enforcement query to cause an additional firing of the AFTER STATEMENT triggers for the referencing table, but that's certainly not per spec. (We're still doing multiple firings of BEFORE STATEMENT triggers, though; is that something worth changing?) Also, forbid using transition tables with column-specific UPDATE triggers. The spec requires such transition tables to show only the tuples for which the UPDATE trigger would have fired, which means maintaining multiple transition tables or else somehow filtering the contents at readout. Maybe someday we'll bother to support that option, but it looks like a lot of trouble for a marginal feature. The transition tables are now managed by the AfterTriggers data structures, rather than being directly the responsibility of ModifyTable nodes. This removes a subtransaction-lifespan memory leak introduced by my previous band-aid patch 3c4359521. In passing, refactor the AfterTriggers data structures to reduce the management overhead for them, by using arrays of structs rather than several parallel arrays for per-query-level and per-subtransaction state. I failed to resist the temptation to do some copy-editing on the SGML docs about triggers, above and beyond merely documenting the effects of this patch. Back-patch to v10, because we don't want the semantics of transition tables to change post-release. Patch by me, with help and review from Thomas Munro. Discussion: https://postgr.es/m/20170909064853.25630.12825@wrigleys.postgresql.org
* Properly check interrupts in execScan.c.Andres Freund2017-09-14
| | | | | | | | | | | | During the development of d47cfef711 the CFI()s in ExecScan() were moved back and forth, ending up in the wrong place. Thus queries that largely spend their time in ExecScan(), and have neither projection nor a qual, can't be cancelled in a timely manner. Reported-By: Jeff Janes Author: Andres Freund Discussion: https://postgr.es/m/CAMkU=1weDXp8eLLPt9SO1LEUsJYYK9cScaGhLKpuN+WbYo9b5g@mail.gmail.com Backpatch: 10, as d47cfef711
* Message style fixesPeter Eisentraut2017-09-11
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* Quick-hack fix for foreign key cascade vs triggers with transition tables.Tom Lane2017-09-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | AFTER triggers using transition tables crashed if they were fired due to a foreign key ON CASCADE update. This is because ExecEndModifyTable flushes the transition tables, on the assumption that any trigger that could need them was already fired during ExecutorFinish. Normally that's true, because we don't allow transition-table-using triggers to be deferred. However, foreign key CASCADE updates force any triggers on the referencing table to be deferred to the outer query level, by means of the EXEC_FLAG_SKIP_TRIGGERS flag. I don't recall all the details of why it's like that and am pretty loath to redesign it right now. Instead, just teach ExecEndModifyTable to skip destroying the TransitionCaptureState when that flag is set. This will allow the transition table data to survive until end of the current subtransaction. This isn't a terribly satisfactory solution, because (1) we might be leaking the transition tables for much longer than really necessary, and (2) as things stand, an AFTER STATEMENT trigger will fire once per RI updating query, ie once per row updated or deleted in the referenced table. I suspect that is not per SQL spec. But redesigning this is a research project that we're certainly not going to get done for v10. So let's go with this hackish answer for now. In passing, tweak AfterTriggerSaveEvent to not save the transition_capture pointer into the event record for a deferrable trigger. This is not necessary to fix the current bug, but it avoids letting dangling pointers to long-gone transition tables persist in the trigger event queue. That's at least a safety feature. It might also allow merging shared trigger states in more cases than before. I added a regression test that demonstrates the crash on unpatched code, and also exposes the behavior of firing the AFTER STATEMENT triggers once per row update. Per bug #14808 from Philippe Beaudoin. Back-patch to v10. Discussion: https://postgr.es/m/20170909064853.25630.12825@wrigleys.postgresql.org
* Even if some partitions are foreign, allow tuple routing.Robert Haas2017-09-07
| | | | | | | | | | This doesn't allow routing tuple to the foreign partitions themselves, but it permits tuples to be routed to regular partitions despite the presence of foreign partitions in the same inheritance hierarchy. Etsuro Fujita, reviewed by Amit Langote and by me. Discussion: http://postgr.es/m/bc3db4c1-1693-3b8a-559f-33ad2b50b7ad@lab.ntt.co.jp
* Improve division of labor between execParallel.c and nodeGather[Merge].c.Tom Lane2017-09-01
| | | | | | | | | | | | | | | | Move the responsibility for creating/destroying TupleQueueReaders into execParallel.c, to avoid duplicative coding in nodeGather.c and nodeGatherMerge.c. Also, instead of having DestroyTupleQueueReader do shm_mq_detach, do it in the caller (which is now only ExecParallelFinish). This means execParallel.c does both the attaching and detaching of the tuple-queue-reader shm_mqs, which seems less weird than the previous arrangement. These changes also eliminate a vestigial memory leak (of the pei->tqueue array). It's now demonstrable that rescans of Gather or GatherMerge don't leak memory. Discussion: https://postgr.es/m/8670.1504192177@sss.pgh.pa.us
* Avoid memory leaks when a GatherMerge node is rescanned.Tom Lane2017-08-31
| | | | | | | | | | | | | | | | | | | | | | | | Rescanning a GatherMerge led to leaking some memory in the executor's query-lifespan context, because most of the node's working data structures were simply abandoned and rebuilt from scratch. In practice, this might never amount to much, given the cost of relaunching worker processes --- but it's still pretty messy, so let's fix it. We can rearrange things so that the tuple arrays are simply cleared and reused, and we don't need to rebuild the TupleTableSlots either, just clear them. One small complication is that because we might get a different number of workers on each iteration, we can't keep the old convention that the leader's gm_slots[] entry is the last one; the leader might clobber a TupleTableSlot that we need for a worker in a future iteration. Hence, adjust the logic so that the leader has slot 0 always, while the active workers have slots 1..n. Back-patch to v10 to keep all the existing versions of nodeGatherMerge.c in sync --- because of the renumbering of the slots, there would otherwise be a very large risk that any future backpatches in this module would introduce bugs. Discussion: https://postgr.es/m/8670.1504192177@sss.pgh.pa.us
* Clean up shm_mq cleanup.Tom Lane2017-08-31
| | | | | | | | | | | | | | | | | | | | | | | | | The logic around shm_mq_detach was a few bricks shy of a load, because (contrary to the comments for shm_mq_attach) all it did was update the shared shm_mq state. That left us leaking a bit of process-local memory, but much worse, the on_dsm_detach callback for shm_mq_detach was still armed. That means that whenever we ultimately detach from the DSM segment, we'd run shm_mq_detach again for already-detached, possibly long-dead queues. This accidentally fails to fail today, because we only ever re-use a shm_mq's memory for another shm_mq, and multiple detach attempts on the last such shm_mq are fairly harmless. But it's gonna bite us someday, so let's clean it up. To do that, change shm_mq_detach's API so it takes a shm_mq_handle not the underlying shm_mq. This makes the callers simpler in most cases anyway. Also fix a few places in parallel.c that were just pfree'ing the handle structs rather than doing proper cleanup. Back-patch to v10 because of the risk that the revenant shm_mq_detach callbacks would cause a live bug sometime. Since this is an API change, it's too late to do it in 9.6. (We could make a variant patch that preserves API, but I'm not excited enough to do that.) Discussion: https://postgr.es/m/8670.1504192177@sss.pgh.pa.us
* Code review for nodeGatherMerge.c.Tom Lane2017-08-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Comment the fields of GatherMergeState, and organize them a bit more sensibly. Comment GMReaderTupleBuffer more usefully too. Improve assorted other comments that were obsolete or just not very good English. Get rid of the use of a GMReaderTupleBuffer for the leader process; that was confusing, since only the "done" field was used, and that in a way redundant with need_to_scan_locally. In gather_merge_init, avoid calling load_tuple_array for already-known-exhausted workers. I'm not sure if there's a live bug there, but the case is unlikely to be well tested due to timing considerations. Remove some useless code, such as duplicating the tts_isempty test done by TupIsNull. Remove useless initialization of ps.qual, replacing that with an assertion that we have no qual to check. (If we did, the code would fail to check it.) Avoid applying heap_copytuple to a null tuple. While that fails to crash, it's confusing and it makes the code less legible not more so IMO. Propagate a couple of these changes into nodeGather.c, as well. Back-patch to v10, partly because of the possibility that the gather_merge_init change is fixing a live bug, but mostly to keep the branches in sync to ease future bug fixes.
* Separate reinitialization of shared parallel-scan state from ExecReScan.Tom Lane2017-08-30
| | | | | | | | | | | | | | | | | | | | | | | | | | Previously, the parallel executor logic did reinitialization of shared state within the ExecReScan code for parallel-aware scan nodes. This is problematic, because it means that the ExecReScan call has to occur synchronously (ie, during the parent Gather node's ReScan call). That is swimming very much against the tide so far as the ExecReScan machinery is concerned; the fact that it works at all today depends on a lot of fragile assumptions, such as that no plan node between Gather and a parallel-aware scan node is parameterized. Another objection is that because ExecReScan might be called in workers as well as the leader, hacky extra tests are needed in some places to prevent unwanted shared-state resets. Hence, let's separate this code into two functions, a ReInitializeDSM call and the ReScan call proper. ReInitializeDSM is called only in the leader and is guaranteed to run before we start new workers. ReScan is returned to its traditional function of resetting only local state, which means that ExecReScan's usual habits of delaying or eliminating child rescan calls are safe again. As with the preceding commit 7df2c1f8d, it doesn't seem to be necessary to make these changes in 9.6, which is a good thing because the FDW and CustomScan APIs are impacted. Discussion: https://postgr.es/m/CAA4eK1JkByysFJNh9M349u_nNjqETuEnY_y1VUc_kJiU0bxtaQ@mail.gmail.com
* Force rescanning of parallel-aware scan nodes below a Gather[Merge].Tom Lane2017-08-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The ExecReScan machinery contains various optimizations for postponing or skipping rescans of plan subtrees; for example a HashAgg node may conclude that it can re-use the table it built before, instead of re-reading its input subtree. But that is wrong if the input contains a parallel-aware table scan node, since the portion of the table scanned by the leader process is likely to vary from one rescan to the next. This explains the timing-dependent buildfarm failures we saw after commit a2b70c89c. The established mechanism for showing that a plan node's output is potentially variable is to mark it as depending on some runtime Param. Hence, to fix this, invent a dummy Param (one that has a PARAM_EXEC parameter number, but carries no actual value) associated with each Gather or GatherMerge node, mark parallel-aware nodes below that node as dependent on that Param, and arrange for ExecReScanGather[Merge] to flag that Param as changed whenever the Gather[Merge] node is rescanned. This solution breaks an undocumented assumption made by the parallel executor logic, namely that all rescans of nodes below a Gather[Merge] will happen synchronously during the ReScan of the top node itself. But that's fundamentally contrary to the design of the ExecReScan code, and so was doomed to fail someday anyway (even if you want to argue that the bug being fixed here wasn't a failure of that assumption). A follow-on patch will address that issue. In the meantime, the worst that's expected to happen is that given very bad timing luck, the leader might have to do all the work during a rescan, because workers think they have nothing to do, if they are able to start up before the eventual ReScan of the leader's parallel-aware table scan node has reset the shared scan state. Although this problem exists in 9.6, there does not seem to be any way for it to manifest there. Without GatherMerge, it seems that a plan tree that has a rescan-short-circuiting node below Gather will always also have one above it that will short-circuit in the same cases, preventing the Gather from being rescanned. Hence we won't take the risk of back-patching this change into 9.6. But v10 needs it. Discussion: https://postgr.es/m/CAA4eK1JkByysFJNh9M349u_nNjqETuEnY_y1VUc_kJiU0bxtaQ@mail.gmail.com
* Fix interaction of triggers, partitioning, and EXPLAIN ANALYZE.Robert Haas2017-08-18
| | | | | | | | | | | Add a new EState member es_leaf_result_relations, so that the trigger code knows about ResultRelInfos created by tuple routing. Also make sure ExplainPrintTriggers knows about partition-related ResultRelInfos. Etsuro Fujita, reviewed by Amit Langote Discussion: http://postgr.es/m/57163e18-8e56-da83-337a-22f2c0008051@lab.ntt.co.jp
* Don't lock tables in RelationGetPartitionDispatchInfo.Robert Haas2017-08-17
| | | | | | | | | | | | Instead, lock them in the caller using find_all_inheritors so that they get locked in the standard order, minimizing deadlock risks. Also in RelationGetPartitionDispatchInfo, avoid opening tables which are not partitioned; there's no need. Amit Langote, reviewed by Ashutosh Bapat and Amit Khandekar Discussion: http://postgr.es/m/91b36fa1-c197-b72f-ca6e-56c593bae68c@lab.ntt.co.jp
* Fix ExecReScanGatherMerge.Tom Lane2017-08-17
| | | | | | | | | Not surprisingly, since it'd never ever been tested, ExecReScanGatherMerge didn't work. Fix it, and add a regression test case to exercise it. Amit Kapila Discussion: https://postgr.es/m/CAA4eK1JkByysFJNh9M349u_nNjqETuEnY_y1VUc_kJiU0bxtaQ@mail.gmail.com
* Add missing call to ExecReScanGatherMerge.Robert Haas2017-08-15
| | | | | | Amit Kapila Discussion: http://postgr.es/m/CAA4eK1KeQWZOoDmDmGMwuqzPW9JhRS+ditQVFdAfGjNmMZzqMQ@mail.gmail.com
* Final pgindent + perltidy run for v10.Tom Lane2017-08-14
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* Remove uses of "slave" in replication contextsPeter Eisentraut2017-08-10
| | | | | This affects mostly code comments, some documentation, and tests. Official APIs already used "standby".
* Improve ExecModifyTable comments.Robert Haas2017-08-03
| | | | | | | | | | | | Some of these comments wrongly implied that only an AFTER ROW trigger will cause a 'wholerow' attribute to be present for a foreign table, but a BEFORE ROW trigger can have the same effect. Others implied that it would always be present for a foreign table, but that's not true either. Etsuro Fujita and Robert Haas Discussion: http://postgr.es/m/10026bc7-1403-ef85-9e43-c6100c1cc0e3@lab.ntt.co.jp
* Teach map_partition_varattnos to handle whole-row expressions.Robert Haas2017-08-03
| | | | | | | | | | Otherwise, partitioned tables with RETURNING expressions or subject to a WITH CHECK OPTION do not work properly. Amit Langote, reviewed by Amit Khandekar and Etsuro Fujita. A few comment changes by me. Discussion: http://postgr.es/m/9a39df80-871e-6212-0684-f93c83be4097@lab.ntt.co.jp
* Fix typoPeter Eisentraut2017-07-31
| | | | Author: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
* Move ExecProcNode from dispatch to function pointer based model.Andres Freund2017-07-30
| | | | | | | | | | | | | | | | | | | | | | This allows us to add stack-depth checks the first time an executor node is called, and skip that overhead on following calls. Additionally it yields a nice speedup. While it'd probably have been a good idea to have that check all along, it has become more important after the new expression evaluation framework in b8d7f053c5c2bf2a7e - there's no stack depth check in common paths anymore now. We previously relied on ExecEvalExpr() being executed somewhere. We should move towards that model for further routines, but as this is required for v10, it seems better to only do the necessary (which already is quite large). Author: Andres Freund, Tom Lane Reported-By: Julien Rouhaud Discussion: https://postgr.es/m/22833.1490390175@sss.pgh.pa.us https://postgr.es/m/b0af9eaa-130c-60d0-9e4e-7a135b1e0c76@dalibo.com
* Move interrupt checking from ExecProcNode() to executor nodes.Andres Freund2017-07-30
| | | | | | | | | | | | | | | | | In a followup commit ExecProcNode(), and especially the large switch it contains, will largely be replaced by a function pointer directly to the correct node. The node functions will then get invoked by a thin inline function wrapper. To avoid having to include miscadmin.h in headers - CHECK_FOR_INTERRUPTS() - move the interrupt checks into the individual executor routines. While looking through all executor nodes, I noticed a number of arguably missing interrupt checks, add these too. Author: Andres Freund, Tom Lane Reviewed-By: Tom Lane Discussion: https://postgr.es/m/22833.1490390175@sss.pgh.pa.us
* Fix partitioning crashes during error reporting.Robert Haas2017-07-24
| | | | | | | | | | In various places where we reverse-map a tuple before calling ExecBuildSlotValueDescription, we neglected to ensure that the slot descriptor matched the tuple stored in it. Amit Langote and Amit Khandekar, reviewed by Etsuro Fujita Discussion: http://postgr.es/m/CAJ3gD9cqpP=WvJj=dv1ONkPWjy8ZuUaOM4_x86i3uQPas=0_jg@mail.gmail.com
* Be more consistent about errors for opfamily member lookup failures.Tom Lane2017-07-24
| | | | | | | | | | | | | | | Add error checks in some places that were calling get_opfamily_member or get_opfamily_proc and just assuming that the call could never fail. Also, standardize the wording for such errors in some other places. None of these errors are expected in normal use, hence they're just elog not ereport. But they may be handy for diagnosing omissions in custom opclasses. Rushabh Lathia found the oversight in RelationBuildPartitionKey(); I found the others by grepping for all callers of these functions. Discussion: https://postgr.es/m/CAGPqQf2R9Nk8htpv0FFi+FP776EwMyGuORpc9zYkZKC8sFQE3g@mail.gmail.com
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