2000-09-29 20:21:41 +02:00
|
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|
/*-------------------------------------------------------------------------
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*
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* nodeSubqueryscan.c
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* Support routines for scanning subqueries (subselects in rangetable).
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*
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2000-10-05 21:11:39 +02:00
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* This is just enough different from sublinks (nodeSubplan.c) to mean that
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* we need two sets of code. Ought to look at trying to unify the cases.
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*
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*
|
2014-01-07 22:05:30 +01:00
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* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
|
2000-09-29 20:21:41 +02:00
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
|
2010-09-20 22:08:53 +02:00
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* src/backend/executor/nodeSubqueryscan.c
|
2000-09-29 20:21:41 +02:00
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*
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*-------------------------------------------------------------------------
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*/
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/*
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* INTERFACE ROUTINES
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* ExecSubqueryScan scans a subquery.
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* ExecSubqueryNext retrieve next tuple in sequential order.
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* ExecInitSubqueryScan creates and initializes a subqueryscan node.
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* ExecEndSubqueryScan releases any storage allocated.
|
2010-07-12 19:01:06 +02:00
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* ExecReScanSubqueryScan rescans the relation
|
2000-09-29 20:21:41 +02:00
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*
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*/
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#include "postgres.h"
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#include "executor/execdebug.h"
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#include "executor/nodeSubqueryscan.h"
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|
2002-12-05 16:50:39 +01:00
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static TupleTableSlot *SubqueryNext(SubqueryScanState *node);
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2000-09-29 20:21:41 +02:00
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/* ----------------------------------------------------------------
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* Scan Support
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* ----------------------------------------------------------------
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*/
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/* ----------------------------------------------------------------
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* SubqueryNext
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*
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* This is a workhorse for ExecSubqueryScan
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* ----------------------------------------------------------------
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*/
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static TupleTableSlot *
|
2002-12-05 16:50:39 +01:00
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SubqueryNext(SubqueryScanState *node)
|
2000-09-29 20:21:41 +02:00
|
|
|
{
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TupleTableSlot *slot;
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|
2001-03-22 07:16:21 +01:00
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/*
|
2006-12-26 22:37:20 +01:00
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* Get the next tuple from the sub-query.
|
2000-09-29 20:21:41 +02:00
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*/
|
2002-12-05 16:50:39 +01:00
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slot = ExecProcNode(node->subplan);
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2000-09-29 20:21:41 +02:00
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|
2005-05-23 00:30:20 +02:00
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/*
|
2010-02-26 03:01:40 +01:00
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* We just return the subplan's result slot, rather than expending extra
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* cycles for ExecCopySlot(). (Our own ScanTupleSlot is used only for
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* EvalPlanQual rechecks.)
|
2005-05-23 00:30:20 +02:00
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|
*/
|
2000-09-29 20:21:41 +02:00
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|
return slot;
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|
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}
|
|
|
|
|
Re-implement EvalPlanQual processing to improve its performance and eliminate
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.
2009-10-26 03:26:45 +01:00
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/*
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* SubqueryRecheck -- access method routine to recheck a tuple in EvalPlanQual
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|
*/
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static bool
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SubqueryRecheck(SubqueryScanState *node, TupleTableSlot *slot)
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|
|
{
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|
/* nothing to check */
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|
return true;
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|
}
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|
2000-09-29 20:21:41 +02:00
|
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/* ----------------------------------------------------------------
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|
* ExecSubqueryScan(node)
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|
*
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|
* Scans the subquery sequentially and returns the next qualifying
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|
|
* tuple.
|
Re-implement EvalPlanQual processing to improve its performance and eliminate
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.
2009-10-26 03:26:45 +01:00
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|
* We call the ExecScan() routine and pass it the appropriate
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* access method functions.
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|
* ----------------------------------------------------------------
|
2000-09-29 20:21:41 +02:00
|
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|
*/
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|
TupleTableSlot *
|
2002-12-05 16:50:39 +01:00
|
|
|
ExecSubqueryScan(SubqueryScanState *node)
|
2000-09-29 20:21:41 +02:00
|
|
|
{
|
Re-implement EvalPlanQual processing to improve its performance and eliminate
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.
2009-10-26 03:26:45 +01:00
|
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|
return ExecScan(&node->ss,
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|
|
(ExecScanAccessMtd) SubqueryNext,
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|
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(ExecScanRecheckMtd) SubqueryRecheck);
|
2000-09-29 20:21:41 +02:00
|
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|
}
|
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|
/* ----------------------------------------------------------------
|
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|
* ExecInitSubqueryScan
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|
* ----------------------------------------------------------------
|
|
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|
*/
|
2002-12-05 16:50:39 +01:00
|
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|
SubqueryScanState *
|
2006-02-28 05:10:28 +01:00
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|
ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
|
2000-09-29 20:21:41 +02:00
|
|
|
{
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|
SubqueryScanState *subquerystate;
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|
|
2006-02-28 05:10:28 +01:00
|
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|
/* check for unsupported flags */
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|
Assert(!(eflags & EXEC_FLAG_MARK));
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|
2011-09-03 21:35:12 +02:00
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|
/* SubqueryScan should not have any "normal" children */
|
2002-12-05 16:50:39 +01:00
|
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|
Assert(outerPlan(node) == NULL);
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|
Assert(innerPlan(node) == NULL);
|
2000-09-29 20:21:41 +02:00
|
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|
|
2001-03-22 07:16:21 +01:00
|
|
|
/*
|
2002-12-05 16:50:39 +01:00
|
|
|
* create state structure
|
2000-09-29 20:21:41 +02:00
|
|
|
*/
|
|
|
|
subquerystate = makeNode(SubqueryScanState);
|
2002-12-05 16:50:39 +01:00
|
|
|
subquerystate->ss.ps.plan = (Plan *) node;
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|
|
subquerystate->ss.ps.state = estate;
|
2000-09-29 20:21:41 +02:00
|
|
|
|
2001-03-22 07:16:21 +01:00
|
|
|
/*
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|
|
|
* Miscellaneous initialization
|
2000-09-29 20:21:41 +02:00
|
|
|
*
|
2001-03-22 07:16:21 +01:00
|
|
|
* create expression context for node
|
2000-09-29 20:21:41 +02:00
|
|
|
*/
|
2002-12-05 16:50:39 +01:00
|
|
|
ExecAssignExprContext(estate, &subquerystate->ss.ps);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* initialize child expressions
|
|
|
|
*/
|
|
|
|
subquerystate->ss.ps.targetlist = (List *)
|
2002-12-13 20:46:01 +01:00
|
|
|
ExecInitExpr((Expr *) node->scan.plan.targetlist,
|
2002-12-05 16:50:39 +01:00
|
|
|
(PlanState *) subquerystate);
|
|
|
|
subquerystate->ss.ps.qual = (List *)
|
2002-12-13 20:46:01 +01:00
|
|
|
ExecInitExpr((Expr *) node->scan.plan.qual,
|
2002-12-05 16:50:39 +01:00
|
|
|
(PlanState *) subquerystate);
|
2000-09-29 20:21:41 +02:00
|
|
|
|
2001-03-22 07:16:21 +01:00
|
|
|
/*
|
|
|
|
* tuple table initialization
|
2000-09-29 20:21:41 +02:00
|
|
|
*/
|
2002-12-05 16:50:39 +01:00
|
|
|
ExecInitResultTupleSlot(estate, &subquerystate->ss.ps);
|
2005-05-23 00:30:20 +02:00
|
|
|
ExecInitScanTupleSlot(estate, &subquerystate->ss);
|
2000-09-29 20:21:41 +02:00
|
|
|
|
2001-03-22 07:16:21 +01:00
|
|
|
/*
|
|
|
|
* initialize subquery
|
2002-12-15 17:17:59 +01:00
|
|
|
*/
|
2007-02-27 02:11:26 +01:00
|
|
|
subquerystate->subplan = ExecInitNode(node->subplan, estate, eflags);
|
2000-09-29 20:21:41 +02:00
|
|
|
|
2002-12-05 16:50:39 +01:00
|
|
|
subquerystate->ss.ps.ps_TupFromTlist = false;
|
2000-09-29 20:21:41 +02:00
|
|
|
|
2005-05-23 00:30:20 +02:00
|
|
|
/*
|
2007-02-27 02:11:26 +01:00
|
|
|
* Initialize scan tuple type (needed by ExecAssignScanProjectionInfo)
|
2005-05-23 00:30:20 +02:00
|
|
|
*/
|
|
|
|
ExecAssignScanType(&subquerystate->ss,
|
2007-02-27 02:11:26 +01:00
|
|
|
ExecGetResultType(subquerystate->subplan));
|
2005-05-23 00:30:20 +02:00
|
|
|
|
2001-03-22 07:16:21 +01:00
|
|
|
/*
|
2003-01-12 23:01:38 +01:00
|
|
|
* Initialize result tuple type and projection info.
|
2000-09-29 20:21:41 +02:00
|
|
|
*/
|
2002-12-05 16:50:39 +01:00
|
|
|
ExecAssignResultTypeFromTL(&subquerystate->ss.ps);
|
2005-05-23 00:30:20 +02:00
|
|
|
ExecAssignScanProjectionInfo(&subquerystate->ss);
|
2000-09-29 20:21:41 +02:00
|
|
|
|
2002-12-05 16:50:39 +01:00
|
|
|
return subquerystate;
|
2000-09-29 20:21:41 +02:00
|
|
|
}
|
|
|
|
|
|
|
|
/* ----------------------------------------------------------------
|
|
|
|
* ExecEndSubqueryScan
|
|
|
|
*
|
|
|
|
* frees any storage allocated through C routines.
|
|
|
|
* ----------------------------------------------------------------
|
|
|
|
*/
|
|
|
|
void
|
2002-12-05 16:50:39 +01:00
|
|
|
ExecEndSubqueryScan(SubqueryScanState *node)
|
2000-09-29 20:21:41 +02:00
|
|
|
{
|
2001-03-22 07:16:21 +01:00
|
|
|
/*
|
2002-12-15 17:17:59 +01:00
|
|
|
* Free the exprcontext
|
2000-09-29 20:21:41 +02:00
|
|
|
*/
|
2002-12-05 16:50:39 +01:00
|
|
|
ExecFreeExprContext(&node->ss.ps);
|
2000-09-29 20:21:41 +02:00
|
|
|
|
2001-03-22 07:16:21 +01:00
|
|
|
/*
|
2002-12-05 16:50:39 +01:00
|
|
|
* clean out the upper tuple table
|
2000-09-29 20:21:41 +02:00
|
|
|
*/
|
2002-12-05 16:50:39 +01:00
|
|
|
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
|
Re-implement EvalPlanQual processing to improve its performance and eliminate
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.
2009-10-26 03:26:45 +01:00
|
|
|
ExecClearTuple(node->ss.ss_ScanTupleSlot);
|
2000-09-29 20:21:41 +02:00
|
|
|
|
2001-03-22 07:16:21 +01:00
|
|
|
/*
|
2000-09-29 20:21:41 +02:00
|
|
|
* close down subquery
|
|
|
|
*/
|
2007-02-27 02:11:26 +01:00
|
|
|
ExecEndNode(node->subplan);
|
2000-09-29 20:21:41 +02:00
|
|
|
}
|
|
|
|
|
|
|
|
/* ----------------------------------------------------------------
|
2010-07-12 19:01:06 +02:00
|
|
|
* ExecReScanSubqueryScan
|
2000-09-29 20:21:41 +02:00
|
|
|
*
|
|
|
|
* Rescans the relation.
|
|
|
|
* ----------------------------------------------------------------
|
|
|
|
*/
|
|
|
|
void
|
2010-07-12 19:01:06 +02:00
|
|
|
ExecReScanSubqueryScan(SubqueryScanState *node)
|
2000-09-29 20:21:41 +02:00
|
|
|
{
|
Re-implement EvalPlanQual processing to improve its performance and eliminate
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.
2009-10-26 03:26:45 +01:00
|
|
|
ExecScanReScan(&node->ss);
|
2000-09-29 20:21:41 +02:00
|
|
|
|
2001-05-08 21:47:02 +02:00
|
|
|
/*
|
|
|
|
* ExecReScan doesn't know about my subplan, so I have to do
|
2005-10-15 04:49:52 +02:00
|
|
|
* changed-parameter signaling myself. This is just as well, because the
|
|
|
|
* subplan has its own memory context in which its chgParam state lives.
|
2001-05-08 21:47:02 +02:00
|
|
|
*/
|
2002-12-05 16:50:39 +01:00
|
|
|
if (node->ss.ps.chgParam != NULL)
|
2003-02-09 01:30:41 +01:00
|
|
|
UpdateChangedParamSet(node->subplan, node->ss.ps.chgParam);
|
2001-10-25 07:50:21 +02:00
|
|
|
|
2001-05-08 21:47:02 +02:00
|
|
|
/*
|
|
|
|
* if chgParam of subnode is not null then plan will be re-scanned by
|
|
|
|
* first ExecProcNode.
|
|
|
|
*/
|
|
|
|
if (node->subplan->chgParam == NULL)
|
2010-07-12 19:01:06 +02:00
|
|
|
ExecReScan(node->subplan);
|
2000-09-29 20:21:41 +02:00
|
|
|
}
|