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path: root/src/backend/executor/nodeSeqscan.c
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* Allow tupleslots to have a fixed tupledesc, use in executor nodes.Andres Freund2018-02-16
| | | | | | | | | | | | | | | | | | | | | The reason for doing so is that it will allow expression evaluation to optimize based on the underlying tupledesc. In particular it will allow to JIT tuple deforming together with the expression itself. For that expression initialization needs to be moved after the relevant slots are initialized - mostly unproblematic, except in the case of nodeWorktablescan.c. After doing so there's no need for ExecAssignResultType() and ExecAssignResultTypeFromTL() anymore, as all former callers have been converted to create a slot with a fixed descriptor. When creating a slot with a fixed descriptor, tts_values/isnull can be allocated together with the main slot, reducing allocation overhead and increasing cache density a bit. Author: Andres Freund Discussion: https://postgr.es/m/20171206093717.vqdxe5icqttpxs3p@alap3.anarazel.de
* Update copyright for 2018Bruce Momjian2018-01-02
| | | | Backpatch-through: certain files through 9.3
* Provide DSM segment to ExecXXXInitializeWorker functions.Andres Freund2017-11-16
| | | | | | | | | | | | Previously, executor nodes running in parallel worker processes didn't have access to the dsm_segment object used for parallel execution. In order to support resource management based on DSM segment lifetime, they need that. So create a ParallelWorkerContext object to hold it and pass it to all InitializeWorker functions. Author: Thomas Munro Reviewed-By: Andres Freund Discussion: https://postgr.es/m/CAEepm=2W=cOkiZxcg6qiFQP-dHUe09aqTrEMM7yJDrHMhDv_RA@mail.gmail.com
* Improve comments for parallel executor estimation functions.Robert Haas2017-10-28
| | | | | | | | | | The previous comment (which was copied as boilerplate from one file to the next) implied that it was the executor node itself which was being serialized, but that's not right. We're not serializing the executor nodes; we're just allowing them to store some additional information in DSM. Adjusts the comment to reflect this. Discussion: http://postgr.es/m/CA+TgmoaHVinxG=3h6qBAsyV8xaDyQwbzK7YZnYfE8nJFMK1=FA@mail.gmail.com
* 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
* 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
* Phase 3 of pgindent updates.Tom Lane2017-06-21
| | | | | | | | | | | | | | | | | | | | | | | | | 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
* Phase 2 of pgindent updates.Tom Lane2017-06-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. 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
* Don't be so trusting that shm_toc_lookup() will always succeed.Tom Lane2017-06-05
| | | | | | | | | | | | | | | | | | Given the possibility of race conditions and so on, it seems entirely unsafe to just assume that shm_toc_lookup() always finds the key it's looking for --- but that was exactly what all but one call site were doing. To fix, add a "bool noError" argument, similarly to what we have in many other functions, and throw an error on an unexpected lookup failure. Remove now-redundant Asserts that a rather random subset of call sites had. I doubt this will throw any light on buildfarm member lorikeet's recent failures, because if an unnoticed lookup failure were involved, you'd kind of expect a null-pointer-dereference crash rather than the observed symptom. But you never know ... and this is better coding practice even if it never catches anything. Discussion: https://postgr.es/m/9697.1496675981@sss.pgh.pa.us
* Faster expression evaluation and targetlist projection.Andres Freund2017-03-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This replaces the old, recursive tree-walk based evaluation, with non-recursive, opcode dispatch based, expression evaluation. Projection is now implemented as part of expression evaluation. This both leads to significant performance improvements, and makes future just-in-time compilation of expressions easier. The speed gains primarily come from: - non-recursive implementation reduces stack usage / overhead - simple sub-expressions are implemented with a single jump, without function calls - sharing some state between different sub-expressions - reduced amount of indirect/hard to predict memory accesses by laying out operation metadata sequentially; including the avoidance of nearly all of the previously used linked lists - more code has been moved to expression initialization, avoiding constant re-checks at evaluation time Future just-in-time compilation (JIT) has become easier, as demonstrated by released patches intended to be merged in a later release, for primarily two reasons: Firstly, due to a stricter split between expression initialization and evaluation, less code has to be handled by the JIT. Secondly, due to the non-recursive nature of the generated "instructions", less performance-critical code-paths can easily be shared between interpreted and compiled evaluation. The new framework allows for significant future optimizations. E.g.: - basic infrastructure for to later reduce the per executor-startup overhead of expression evaluation, by caching state in prepared statements. That'd be helpful in OLTPish scenarios where initialization overhead is measurable. - optimizing the generated "code". A number of proposals for potential work has already been made. - optimizing the interpreter. Similarly a number of proposals have been made here too. The move of logic into the expression initialization step leads to some backward-incompatible changes: - Function permission checks are now done during expression initialization, whereas previously they were done during execution. In edge cases this can lead to errors being raised that previously wouldn't have been, e.g. a NULL array being coerced to a different array type previously didn't perform checks. - The set of domain constraints to be checked, is now evaluated once during expression initialization, previously it was re-built every time a domain check was evaluated. For normal queries this doesn't change much, but e.g. for plpgsql functions, which caches ExprStates, the old set could stick around longer. The behavior around might still change. Author: Andres Freund, with significant changes by Tom Lane, changes by Heikki Linnakangas Reviewed-By: Tom Lane, Heikki Linnakangas Discussion: https://postgr.es/m/20161206034955.bh33paeralxbtluv@alap3.anarazel.de
* Remove obsoleted code relating to targetlist SRF evaluation.Andres Freund2017-01-19
| | | | | | | | | | | | | Since 69f4b9c plain expression evaluation (and thus normal projection) can't return sets of tuples anymore. Thus remove code dealing with that possibility. This will require adjustments in external code using ExecEvalExpr()/ExecProject() - that should neither be hard nor very common. Author: Andres Freund and Tom Lane Discussion: https://postgr.es/m/20160822214023.aaxz5l4igypowyri@alap3.anarazel.de
* Update copyright via script for 2017Bruce Momjian2017-01-03
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* pgindent run for 9.6Robert Haas2016-06-09
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* Update copyright for 2016Bruce Momjian2016-01-02
| | | | Backpatch certain files through 9.1
* Make sequential scans parallel-aware.Robert Haas2015-11-11
| | | | | | | | | | | | | | In addition, this path fills in a number of missing bits and pieces in the parallel infrastructure. Paths and plans now have a parallel_aware flag indicating whether whatever parallel-aware logic they have should be engaged. It is believed that we will need this flag for a number of path/plan types, not just sequential scans, which is why the flag is generic rather than part of the SeqScan structures specifically. Also, execParallel.c now gives parallel nodes a chance to initialize their PlanState nodes from the DSM during parallel worker startup. Amit Kapila, with a fair amount of adjustment by me. Review of previous patch versions by Haribabu Kommi and others.
* Update copyright for 2015Bruce Momjian2015-01-06
| | | | Backpatch certain files through 9.0
* Remove dead code supporting mark/restore in SeqScan, TidScan, ValuesScan.Tom Lane2014-11-20
| | | | | | | | | | | | There seems no prospect that any of this will ever be useful, and indeed it's questionable whether some of it would work if it ever got called; it's certainly not been exercised in a very long time, if ever. So let's get rid of it, and make the comments about mark/restore in execAmi.c less wishy-washy. The mark/restore support for Result nodes is also currently dead code, but that's due to planner limitations not because it's impossible that it could be useful. So I left it in.
* Update copyright for 2014Bruce Momjian2014-01-07
| | | | | Update all files in head, and files COPYRIGHT and legal.sgml in all back branches.
* pgindent run for release 9.3Bruce Momjian2013-05-29
| | | | | This is the first run of the Perl-based pgindent script. Also update pgindent instructions.
* Incidental cleanup of matviews code.Tom Lane2013-04-27
| | | | | | | | | | | | | | | | | Move checking for unscannable matviews into ExecOpenScanRelation, which is a better place for it first because the open relation is already available (saving a relcache lookup cycle), and second because this eliminates the problem of telling the difference between rangetable entries that will or will not be scanned by the query. In particular we can get rid of the not-terribly-well-thought-out-or-implemented isResultRel field that the initial matviews patch added to RangeTblEntry. Also get rid of entirely unnecessary scannability check in the rewriter, and a bogus decision about whether RefreshMatViewStmt requires a parse-time snapshot. catversion bump due to removal of a RangeTblEntry field, which changes stored rules.
* Update copyrights for 2013Bruce Momjian2013-01-01
| | | | | Fully update git head, and update back branches in ./COPYRIGHT and legal.sgml files.
* Update copyright notices for year 2012.Bruce Momjian2012-01-01
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* Remove unnecessary #include references, per pgrminclude script.Bruce Momjian2011-09-01
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* Move Trigger and TriggerDesc structs out of rel.h into a new reltrigger.hAlvaro Herrera2011-07-04
| | | | | This lets us stop including rel.h into execnodes.h, which is a widely used header.
* Move the PredicateLockRelation() call from nodeSeqscan.c to heapam.c. It'sHeikki Linnakangas2011-06-29
| | | | | | | | | | | | | | | | | | | | more consistent that way, since all the other PredicateLock* calls are made in various heapam.c and index AM functions. The call in nodeSeqscan.c was unnecessarily aggressive anyway, there's no need to try to lock the relation every time a tuple is fetched, it's enough to do it once. This has the user-visible effect that if a seq scan is initialized in the executor, but never executed, we now acquire the predicate lock on the heap relation anyway. We could avoid that by taking the lock on the first heap_getnext() call instead, but it doesn't seem worth the trouble given that it feels more natural to do it in heap_beginscan(). Also, remove the retail PredicateLockTuple() calls from heap_getnext(). In a seqscan, started with heap_begin(), we're holding a whole-relation predicate lock on the heap so there's no need to lock the tuples individually. Kevin Grittner and me
* Make non-MVCC snapshots exempt from predicate locking. Scans with non-MVCCHeikki Linnakangas2011-06-15
| | | | | | | | snapshots, like in REINDEX, are basically non-transactional operations. The DDL operation itself might participate in SSI, but there's separate functions for that. Kevin Grittner and Dan Ports, with some changes by me.
* Implement genuine serializable isolation level.Heikki Linnakangas2011-02-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Until now, our Serializable mode has in fact been what's called Snapshot Isolation, which allows some anomalies that could not occur in any serialized ordering of the transactions. This patch fixes that using a method called Serializable Snapshot Isolation, based on research papers by Michael J. Cahill (see README-SSI for full references). In Serializable Snapshot Isolation, transactions run like they do in Snapshot Isolation, but a predicate lock manager observes the reads and writes performed and aborts transactions if it detects that an anomaly might occur. This method produces some false positives, ie. it sometimes aborts transactions even though there is no anomaly. To track reads we implement predicate locking, see storage/lmgr/predicate.c. Whenever a tuple is read, a predicate lock is acquired on the tuple. Shared memory is finite, so when a transaction takes many tuple-level locks on a page, the locks are promoted to a single page-level lock, and further to a single relation level lock if necessary. To lock key values with no matching tuple, a sequential scan always takes a relation-level lock, and an index scan acquires a page-level lock that covers the search key, whether or not there are any matching keys at the moment. A predicate lock doesn't conflict with any regular locks or with another predicate locks in the normal sense. They're only used by the predicate lock manager to detect the danger of anomalies. Only serializable transactions participate in predicate locking, so there should be no extra overhead for for other transactions. Predicate locks can't be released at commit, but must be remembered until all the transactions that overlapped with it have completed. That means that we need to remember an unbounded amount of predicate locks, so we apply a lossy but conservative method of tracking locks for committed transactions. If we run short of shared memory, we overflow to a new "pg_serial" SLRU pool. We don't currently allow Serializable transactions in Hot Standby mode. That would be hard, because even read-only transactions can cause anomalies that wouldn't otherwise occur. Serializable isolation mode now means the new fully serializable level. Repeatable Read gives you the old Snapshot Isolation level that we have always had. Kevin Grittner and Dan Ports, reviewed by Jeff Davis, Heikki Linnakangas and Anssi Kääriäinen
* Stamp copyrights for year 2011.Bruce Momjian2011-01-01
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* Remove cvs keywords from all files.Magnus Hagander2010-09-20
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* Make NestLoop plan nodes pass outer-relation variables into their innerTom Lane2010-07-12
| | | | | | | | | | | | relation using the general PARAM_EXEC executor parameter mechanism, rather than the ad-hoc kluge of passing the outer tuple down through ExecReScan. The previous method was hard to understand and could never be extended to handle parameters coming from multiple join levels. This patch doesn't change the set of possible plans nor have any significant performance effect, but it's necessary infrastructure for future generalization of the concept of an inner indexscan plan. ExecReScan's second parameter is now unused, so it's removed.
* pgindent run for 9.0Bruce Momjian2010-02-26
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* Update copyright for the year 2010.Bruce Momjian2010-01-02
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* Re-implement EvalPlanQual processing to improve its performance and eliminateTom Lane2009-10-26
| | | | | | | | | | | | | | | | | | | | | | | | | a lot of strange behaviors that occurred in join cases. We now identify the "current" row for every joined relation in UPDATE, DELETE, and SELECT FOR UPDATE/SHARE queries. If an EvalPlanQual recheck is necessary, we jam the appropriate row into each scan node in the rechecking plan, forcing it to emit only that one row. The former behavior could rescan the whole of each joined relation for each recheck, which was terrible for performance, and what's much worse could result in duplicated output tuples. Also, the original implementation of EvalPlanQual could not re-use the recheck execution tree --- it had to go through a full executor init and shutdown for every row to be tested. To avoid this overhead, I've associated a special runtime Param with each LockRows or ModifyTable plan node, and arranged to make every scan node below such a node depend on that Param. Thus, by signaling a change in that Param, the EPQ machinery can just rescan the already-built test plan. This patch also adds a prohibition on set-returning functions in the targetlist of SELECT FOR UPDATE/SHARE. This is needed to avoid the duplicate-output-tuple problem. It seems fairly reasonable since the other restrictions on SELECT FOR UPDATE are meant to ensure that there is a unique correspondence between source tuples and result tuples, which an output SRF destroys as much as anything else does.
* Remove no-longer-needed ExecCountSlots infrastructure.Tom Lane2009-09-27
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* Update copyright for 2009.Bruce Momjian2009-01-01
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* Improve our #include situation by moving pointer types away from theAlvaro Herrera2008-06-19
| | | | | | | corresponding struct definitions. This allows other headers to avoid including certain highly-loaded headers such as rel.h and relscan.h, instead using just relcache.h, heapam.h or genam.h, which are more lightweight and thus cause less unnecessary dependencies.
* Update copyrights in source tree to 2008.Bruce Momjian2008-01-01
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* Update CVS HEAD for 2007 copyright. Back branches are typically notBruce Momjian2007-01-05
| | | | back-stamped for this.
* Repair bug #2839: the various ExecReScan functions need to resetTom Lane2006-12-26
| | | | | | | | | ps_TupFromTlist in plan nodes that make use of it. This was being done correctly in join nodes and Result nodes but not in any relation-scan nodes. Bug would lead to bogus results if a set-returning function appeared in the targetlist of a subquery that could be rescanned after partial execution, for example a subquery within EXISTS(). Bug has been around forever :-( ... surprising it wasn't reported before.
* pgindent run for 8.2.Bruce Momjian2006-10-04
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* Remove 576 references of include files that were not needed.Bruce Momjian2006-07-14
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* Fix problems with cached tuple descriptors disappearing while still in useTom Lane2006-06-16
| | | | | | | | | | by creating a reference-count mechanism, similar to what we did a long time ago for catcache entries. The back branches have an ugly solution involving lots of extra copies, but this way is more efficient. Reference counting is only applied to tupdescs that are actually in caches --- there seems no need to use it for tupdescs that are generated in the executor, since they'll go away during plan shutdown by virtue of being in the per-query memory context. Neil Conway and Tom Lane
* Update copyright for 2006. Update scripts.Bruce Momjian2006-03-05
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* Extend the ExecInitNode API so that plan nodes receive a set of flagTom Lane2006-02-28
| | | | | | | | | | | | bits indicating which optional capabilities can actually be exercised at runtime. This will allow Sort and Material nodes, and perhaps later other nodes, to avoid unnecessary overhead in common cases. This commit just adds the infrastructure and arranges to pass the correct flag values down to plan nodes; none of the actual optimizations are here yet. I'm committing this separately in case anyone wants to measure the added overhead. (It should be negligible.) Simon Riggs and Tom Lane
* Adjust scan plan nodes to avoid getting an extra AccessShareLock on aTom Lane2005-12-02
| | | | | | relation if it's already been locked by execMain.c as either a result relation or a FOR UPDATE/SHARE relation. This avoids an extra trip to the shared lock manager state. Per my suggestion yesterday.
* Improve ExecStoreTuple to be smarter about replacing the contents ofTom Lane2005-11-25
| | | | | | | | | | | | | | a TupleTableSlot: instead of calling ExecClearTuple, inline the needed operations, so that we can avoid redundant steps. In particular, when the old and new tuples are both on the same disk page, avoid releasing and re-acquiring the buffer pin --- this saves work in both the bufmgr and ResourceOwner modules. To make this improvement actually useful, partially revert a change I made on 2004-04-21 that caused SeqNext et al to call ExecClearTuple before ExecStoreTuple. The motivation for that, to avoid grabbing the BufMgrLock separately for releasing the old buffer and grabbing the new one, no longer applies. My profiling says that this saves about 5% of the CPU time for an all-in-memory seqscan.
* Standard pgindent run for 8.1.Bruce Momjian2005-10-15
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* Fix latent bug in ExecSeqRestrPos: it leaves the plan node's result slotTom Lane2005-05-15
| | | | | | | in an inconsistent state. (This is only latent because in reality ExecSeqRestrPos is dead code at the moment ... but someday maybe it won't be.) Add some comments about what the API for plan node mark/restore actually is, because it's not immediately obvious.
* Revise TupleTableSlot code to avoid unnecessary construction and disassemblyTom Lane2005-03-16
| | | | | | | | | | | | | | | | | | | | | of tuples when passing data up through multiple plan nodes. A slot can now hold either a normal "physical" HeapTuple, or a "virtual" tuple consisting of Datum/isnull arrays. Upper plan levels can usually just copy the Datum arrays, avoiding heap_formtuple() and possible subsequent nocachegetattr() calls to extract the data again. This work extends Atsushi Ogawa's earlier patch, which provided the key idea of adding Datum arrays to TupleTableSlots. (I believe however that something like this was foreseen way back in Berkeley days --- see the old comment on ExecProject.) A test case involving many levels of join of fairly wide tables (about 80 columns altogether) showed about 3x overall speedup, though simple queries will probably not be helped very much. I have also duplicated some code in heaptuple.c in order to provide versions of heap_formtuple and friends that use "bool" arrays to indicate null attributes, instead of the old convention of "char" arrays containing either 'n' or ' '. This provides a better match to the convention used by ExecEvalExpr. While I have not made a concerted effort to get rid of uses of the old routines, I think they should be deprecated and eventually removed.
* Tag appropriate files for rc3PostgreSQL Daemon2004-12-31
| | | | | | | | Also performed an initial run through of upgrading our Copyright date to extend to 2005 ... first run here was very simple ... change everything where: grep 1996-2004 && the word 'Copyright' ... scanned through the generated list with 'less' first, and after, to make sure that I only picked up the right entries ...
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