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path: root/src/backend/executor/execScan.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
* Avoid projecting tuples unnecessarily in Gather and Gather Merge.Robert Haas2017-11-25
| | | | | | | | | | | | | It's most often the case that the target list for the Gather (Merge) node matches the target list supplied by the underlying plan node; when this is so, we can avoid the overhead of projecting. This depends on commit f455e1125e2588d4cd4fc663c6a10da4e003a3b5 for proper functioning. Idea by Andres Freund. Patch by me. Review by Amit Kapila. Discussion: http://postgr.es/m/CA+TgmoZ0ZL=cesZFq8c9NnfK6bqy-wwUd3_74iYGodYrSoQ7Fw@mail.gmail.com
* 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
* Change tupledesc->attrs[n] to TupleDescAttr(tupledesc, n).Andres Freund2017-08-20
| | | | | | | | | | | This is a mechanical change in preparation for a later commit that will change the layout of TupleDesc. Introducing a macro to abstract the details of where attributes are stored will allow us to change that in separate step and revise it in future. Author: Thomas Munro, editorialized by Andres Freund Reviewed-By: Andres Freund Discussion: https://postgr.es/m/CAEepm=0ZtQ-SpsgCyzzYpsXS6e=kZWqk3g5Ygn3MDV7A8dabUA@mail.gmail.com
* 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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* Update copyright for 2016Bruce Momjian2016-01-02
| | | | Backpatch certain files through 9.1
* Allow foreign and custom joins to handle EvalPlanQual rechecks.Robert Haas2015-12-08
| | | | | | | | | | | | | | | | | | | | | | | Commit e7cb7ee14555cc9c5773e2c102efd6371f6f2005 provided basic infrastructure for allowing a foreign data wrapper or custom scan provider to replace a join of one or more tables with a scan. However, this infrastructure failed to take into account the need for possible EvalPlanQual rechecks, and ExecScanFetch would fail an assertion (or just overwrite memory) if such a check was attempted for a plan containing a pushed-down join. To fix, adjust the EPQ machinery to skip some processing steps when scanrelid == 0, making those the responsibility of scan's recheck method, which also has the responsibility in this case of correctly populating the relevant slot. To allow foreign scans to gain control in the right place to make use of this new facility, add a new, optional RecheckForeignScan method. Also, allow a foreign scan to have a child plan, which can be used to correctly populate the slot (or perhaps for something else, but this is the only use currently envisioned). KaiGai Kohei, reviewed by Robert Haas, Etsuro Fujita, and Kyotaro Horiguchi.
* Code review for foreign/custom join pushdown patch.Tom Lane2015-05-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit e7cb7ee14555cc9c5773e2c102efd6371f6f2005 included some design decisions that seem pretty questionable to me, and there was quite a lot of stuff not to like about the documentation and comments. Clean up as follows: * Consider foreign joins only between foreign tables on the same server, rather than between any two foreign tables with the same underlying FDW handler function. In most if not all cases, the FDW would simply have had to apply the same-server restriction itself (far more expensively, both for lack of caching and because it would be repeated for each combination of input sub-joins), or else risk nasty bugs. Anyone who's really intent on doing something outside this restriction can always use the set_join_pathlist_hook. * Rename fdw_ps_tlist/custom_ps_tlist to fdw_scan_tlist/custom_scan_tlist to better reflect what they're for, and allow these custom scan tlists to be used even for base relations. * Change make_foreignscan() API to include passing the fdw_scan_tlist value, since the FDW is required to set that. Backwards compatibility doesn't seem like an adequate reason to expect FDWs to set it in some ad-hoc extra step, and anyway existing FDWs can just pass NIL. * Change the API of path-generating subroutines of add_paths_to_joinrel, and in particular that of GetForeignJoinPaths and set_join_pathlist_hook, so that various less-used parameters are passed in a struct rather than as separate parameter-list entries. The objective here is to reduce the probability that future additions to those parameter lists will result in source-level API breaks for users of these hooks. It's possible that this is even a small win for the core code, since most CPU architectures can't pass more than half a dozen parameters efficiently anyway. I kept root, joinrel, outerrel, innerrel, and jointype as separate parameters to reduce code churn in joinpath.c --- in particular, putting jointype into the struct would have been problematic because of the subroutines' habit of changing their local copies of that variable. * Avoid ad-hocery in ExecAssignScanProjectionInfo. It was probably all right for it to know about IndexOnlyScan, but if the list is to grow we should refactor the knowledge out to the callers. * Restore nodeForeignscan.c's previous use of the relcache to avoid extra GetFdwRoutine lookups for base-relation scans. * Lots of cleanup of documentation and missed comments. Re-order some code additions into more logical places.
* Allow FDWs and custom scan providers to replace joins with scans.Robert Haas2015-05-01
| | | | | | | | | | | | | | | | | Foreign data wrappers can use this capability for so-called "join pushdown"; that is, instead of executing two separate foreign scans and then joining the results locally, they can generate a path which performs the join on the remote server and then is scanned locally. This commit does not extend postgres_fdw to take advantage of this capability; it just provides the infrastructure. Custom scan providers can use this in a similar way. Previously, it was only possible for a custom scan provider to scan a single relation. Now, it can scan an entire join tree, provided of course that it knows how to produce the same results that the join would have produced if executed normally. KaiGai Kohei, reviewed by Shigeru Hanada, Ashutosh Bapat, and me.
* Update copyright for 2015Bruce Momjian2015-01-06
| | | | Backpatch certain files through 9.0
* Fix typo in C comment.Kevin Grittner2014-08-05
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* pgindent run for 9.4Bruce Momjian2014-05-06
| | | | | This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.
* Update copyright for 2014Bruce Momjian2014-01-07
| | | | | Update all files in head, and files COPYRIGHT and legal.sgml in all back branches.
* 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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* Rearrange the implementation of index-only scans.Tom Lane2011-10-11
| | | | | | | | | | | | | | | | | | | | | | This commit changes index-only scans so that data is read directly from the index tuple without first generating a faux heap tuple. The only immediate benefit is that indexes on system columns (such as OID) can be used in index-only scans, but this is necessary infrastructure if we are ever to support index-only scans on expression indexes. The executor is now ready for that, though the planner still needs substantial work to recognize the possibility. To do this, Vars in index-only plan nodes have to refer to index columns not heap columns. I introduced a new special varno, INDEX_VAR, to mark such Vars to avoid confusion. (In passing, this commit renames the two existing special varnos to OUTER_VAR and INNER_VAR.) This allows ruleutils.c to handle them with logic similar to what we use for subplan reference Vars. Since index-only scans are now fundamentally different from regular indexscans so far as their expression subtrees are concerned, I also chose to change them to have their own plan node type (and hence, their own executor source file).
* Make EXPLAIN ANALYZE report the numbers of rows rejected by filter steps.Tom Lane2011-09-22
| | | | | | | | | | | | | | | This provides information about the numbers of tuples that were visited but not returned by table scans, as well as the numbers of join tuples that were considered and discarded within a join plan node. There is still some discussion going on about the best way to report counts for outer-join situations, but I think most of what's in the patch would not change if we revise that, so I'm going to go ahead and commit it as-is. Documentation changes to follow (they weren't in the submitted patch either). Marko Tiikkaja, reviewed by Marc Cousin, somewhat revised by Tom
* Reset per-tuple memory context between every row in a scan node, even whenHeikki Linnakangas2011-05-21
| | | | | | there's no quals or projections. Currently this only matters for foreign scans, as none of the other scan nodes litter the per-tuple memory context when there's no quals or projections.
* 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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* 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.
* Revert DTrace patch from Robert LorBruce Momjian2009-04-02
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* Add support for additional DTrace probes.Bruce Momjian2009-04-02
| | | | Robert Lor
* Update copyright for 2009.Bruce Momjian2009-01-01
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* Update copyrights in source tree to 2008.Bruce Momjian2008-01-01
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* pgindent run for 8.3.Bruce Momjian2007-11-15
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* Repair failure to check that a table is still compatible with a previouslyTom Lane2007-02-02
| | | | | | | | | | | | | | | | | | | | | | made query plan. Use of ALTER COLUMN TYPE creates a hazard for cached query plans: they could contain Vars that claim a column has a different type than it now has. Fix this by checking during plan startup that Vars at relation scan level match the current relation tuple descriptor. Since at that point we already have at least AccessShareLock, we can be sure the column type will not change underneath us later in the query. However, since a backend's locks do not conflict against itself, there is still a hole for an attacker to exploit: he could try to execute ALTER COLUMN TYPE while a query is in progress in the current backend. Seal that hole by rejecting ALTER TABLE whenever the target relation is already open in the current backend. This is a significant security hole: not only can one trivially crash the backend, but with appropriate misuse of pass-by-reference datatypes it is possible to read out arbitrary locations in the server process's memory, which could allow retrieving database content the user should not be able to see. Our thanks to Jeff Trout for the initial report. Security: CVE-2007-0556
* Relax an Assert() that has been found to be too strict in some situationsTom Lane2007-01-24
| | | | | | | involving unions of types having typmods. Variants of the failure are known to occur in 8.1 and up; not sure if it's possible in 8.0 and 7.4, but since the code exists that far back, I'll just patch 'em all. Per report from Brian Hurt.
* Update CVS HEAD for 2007 copyright. Back branches are typically notBruce Momjian2007-01-05
| | | | back-stamped for this.
* Update copyright for 2006. Update scripts.Bruce Momjian2006-03-05
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* Standard pgindent run for 8.1.Bruce Momjian2005-10-15
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* Teach the planner to remove SubqueryScan nodes from the plan if theyTom Lane2005-05-22
| | | | | | | | | aren't doing anything useful (ie, neither selection nor projection). Also, extend to SubqueryScan the hacks already in place to avoid unnecessary ExecProject calls when the result would just be the same tuple the subquery already delivered. This saves some overhead in UNION and other set operations, as well as avoiding overhead for unflatten-able subqueries. Per example from Sokolov Yura.
* 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 ...
* Pgindent run for 8.0.Bruce Momjian2004-08-29
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* Update copyright to 2004.Bruce Momjian2004-08-29
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* Reimplement the linked list data structure used throughout the backend.Neil Conway2004-05-26
| | | | | | | | | | | | | | | | In the past, we used a 'Lispy' linked list implementation: a "list" was merely a pointer to the head node of the list. The problem with that design is that it makes lappend() and length() linear time. This patch fixes that problem (and others) by maintaining a count of the list length and a pointer to the tail node along with each head node pointer. A "list" is now a pointer to a structure containing some meta-data about the list; the head and tail pointers in that structure refer to ListCell structures that maintain the actual linked list of nodes. The function names of the list API have also been changed to, I hope, be more logically consistent. By default, the old function names are still available; they will be disabled-by-default once the rest of the tree has been updated to use the new API names.
* Fix oversight in optimization that avoids an unnecessary projection stepTom Lane2004-01-22
| | | | | | when scanning a table that we need all the columns from. In case of SELECT INTO, we have to check that the hasoids flag matches the desired output type, too. Per report from Mike Mascari.
* $Header: -> $PostgreSQL Changes ...PostgreSQL Daemon2003-11-29
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* tlist_matches_tupdesc() needs to defend itself against dropped columns.Tom Lane2003-09-25
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* Another pgindent run with updated typedefs.Bruce Momjian2003-08-08
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* Suppress unused-variable warnings when building without Asserts.Tom Lane2003-08-08
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* Update copyrights to 2003.Bruce Momjian2003-08-04
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* pgindent run.Bruce Momjian2003-08-04
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* Tweak planner and executor to avoid doing ExecProject() in table scanTom Lane2003-02-03
| | | | | | | | nodes where it's not really necessary. In many cases where the scan node is not the topmost plan node (eg, joins, aggregation), it's possible to just return the table tuple directly instead of generating an intermediate projection tuple. In preliminary testing, this reduced the CPU time needed for 'SELECT COUNT(*) FROM foo' by about 10%.
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