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Re-implement EvalPlanQual processing to improve its performance and eliminate

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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.
This commit is contained in:
Tom Lane
2009-10-26 02:26:45 +00:00
parent 76d8883c8e
commit 9f2ee8f287
50 changed files with 1547 additions and 1018 deletions
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28
src/backend/optimizer/plan/setrefs.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.153 2009/10/14 22:14:22 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.154 2009/10/26 02:26:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -166,7 +166,7 @@ static bool extract_query_dependencies_walker(Node *node,
* glob: global data for planner run
* plan: the topmost node of the plan
* rtable: the rangetable for the current subquery
* rowmarks: the RowMarkClause list for the current subquery
* rowmarks: the PlanRowMark list for the current subquery
*
* The return value is normally the same Plan node passed in, but can be
* different when the passed-in Plan is a SubqueryScan we decide isn't needed.
@ -235,21 +235,22 @@ set_plan_references(PlannerGlobal *glob, Plan *plan,
}
/*
* Adjust RT indexes of RowMarkClauses and add to final rowmarks list
* Adjust RT indexes of PlanRowMarks and add to final rowmarks list
*/
foreach(lc, rowmarks)
{
RowMarkClause *rc = (RowMarkClause *) lfirst(lc);
RowMarkClause *newrc;
PlanRowMark *rc = (PlanRowMark *) lfirst(lc);
PlanRowMark *newrc;
/* flat copy to duplicate all the scalar fields */
newrc = (RowMarkClause *) palloc(sizeof(RowMarkClause));
memcpy(newrc, rc, sizeof(RowMarkClause));
Assert(IsA(rc, PlanRowMark));
/* flat copy is enough since all fields are scalars */
newrc = (PlanRowMark *) palloc(sizeof(PlanRowMark));
memcpy(newrc, rc, sizeof(PlanRowMark));
/* adjust indexes */
newrc->rti += rtoffset;
newrc->prti += rtoffset;
/* rowmarkId must NOT be adjusted */
glob->finalrowmarks = lappend(glob->finalrowmarks, newrc);
}
@ -434,7 +435,7 @@ set_plan_refs(PlannerGlobal *glob, Plan *plan, int rtoffset)
foreach(l, splan->rowMarks)
{
RowMarkClause *rc = (RowMarkClause *) lfirst(l);
PlanRowMark *rc = (PlanRowMark *) lfirst(l);
rc->rti += rtoffset;
rc->prti += rtoffset;
@ -502,6 +503,13 @@ set_plan_refs(PlannerGlobal *glob, Plan *plan, int rtoffset)
{
lfirst_int(l) += rtoffset;
}
foreach(l, splan->rowMarks)
{
PlanRowMark *rc = (PlanRowMark *) lfirst(l);
rc->rti += rtoffset;
rc->prti += rtoffset;
}
foreach(l, splan->plans)
{
lfirst(l) = set_plan_refs(glob,