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Move the handling of SELECT FOR UPDATE locking and rechecking out of

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execMain.c and into a new plan node type LockRows.  Like the recent change
to put table updating into a ModifyTable plan node, this increases planning
flexibility by allowing the operations to occur below the top level of the
plan tree.  It's necessary in any case to restore the previous behavior of
having FOR UPDATE locking occur before ModifyTable does.

This partially refactors EvalPlanQual to allow multiple rows-under-test
to be inserted into the EPQ machinery before starting an EPQ test query.
That isn't sufficient to fix EPQ's general bogosity in the face of plans
that return multiple rows per test row, though.  Since this patch is
mostly about getting some plan node infrastructure in place and not about
fixing ten-year-old bugs, I will leave EPQ improvements for another day.

Another behavioral change that we could now think about is doing FOR UPDATE
before LIMIT, but that too seems like it should be treated as a followon
patch.
This commit is contained in:
Tom Lane
2009-10-12 18:10:51 +00:00
parent 05d249717d
commit 0adaf4cb31
32 changed files with 882 additions and 320 deletions
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54
src/backend/optimizer/plan/planner.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.258 2009/10/10 01:43:49 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.259 2009/10/12 18:10:48 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -132,7 +132,8 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
PlannerInfo *root;
Plan *top_plan;
ListCell *lp,
*lr;
*lrt,
*lrm;
/* Cursor options may come from caller or from DECLARE CURSOR stmt */
if (parse->utilityStmt &&
@ -151,11 +152,14 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
glob->paramlist = NIL;
glob->subplans = NIL;
glob->subrtables = NIL;
glob->subrowmarks = NIL;
glob->rewindPlanIDs = NULL;
glob->finalrtable = NIL;
glob->finalrowmarks = NIL;
glob->relationOids = NIL;
glob->invalItems = NIL;
glob->lastPHId = 0;
glob->lastRowmarkId = 0;
glob->transientPlan = false;
/* Determine what fraction of the plan is likely to be scanned */
@ -202,15 +206,25 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
/* final cleanup of the plan */
Assert(glob->finalrtable == NIL);
top_plan = set_plan_references(glob, top_plan, root->parse->rtable);
Assert(glob->finalrowmarks == NIL);
top_plan = set_plan_references(glob, top_plan,
root->parse->rtable,
root->parse->rowMarks);
/* ... and the subplans (both regular subplans and initplans) */
Assert(list_length(glob->subplans) == list_length(glob->subrtables));
forboth(lp, glob->subplans, lr, glob->subrtables)
Assert(list_length(glob->subplans) == list_length(glob->subrowmarks));
lrt = list_head(glob->subrtables);
lrm = list_head(glob->subrowmarks);
foreach(lp, glob->subplans)
{
Plan *subplan = (Plan *) lfirst(lp);
List *subrtable = (List *) lfirst(lr);
List *subrtable = (List *) lfirst(lrt);
List *subrowmark = (List *) lfirst(lrm);
lfirst(lp) = set_plan_references(glob, subplan, subrtable);
lfirst(lp) = set_plan_references(glob, subplan,
subrtable, subrowmark);
lrt = lnext(lrt);
lrm = lnext(lrm);
}
/* build the PlannedStmt result */
@ -227,7 +241,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
result->intoClause = parse->intoClause;
result->subplans = glob->subplans;
result->rewindPlanIDs = glob->rewindPlanIDs;
result->rowMarks = parse->rowMarks;
result->rowMarks = glob->finalrowmarks;
result->relationOids = glob->relationOids;
result->invalItems = glob->invalItems;
result->nParamExec = list_length(glob->paramlist);
@ -349,6 +363,21 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
}
}
/*
* Assign unique IDs (unique within this planner run) to RowMarkClauses.
* We can't identify them just by RT index because that will change
* during final rtable flattening, and we don't want to have to go back
* and change the resnames assigned to junk CTID tlist entries at that
* point. Do it now before expanding inheritance sets, because child
* relations should inherit their parents' rowmarkId.
*/
foreach(l, parse->rowMarks)
{
RowMarkClause *rc = (RowMarkClause *) lfirst(l);
rc->rowmarkId = ++(root->glob->lastRowmarkId);
}
/*
* Expand any rangetable entries that are inheritance sets into "append
* relations". This can add entries to the rangetable, but they must be
@ -1588,7 +1617,7 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
}
/*
* Finally, if there is a LIMIT/OFFSET clause, add the LIMIT node.
* If there is a LIMIT/OFFSET clause, add the LIMIT node.
*/
if (parse->limitCount || parse->limitOffset)
{
@ -1599,6 +1628,15 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
count_est);
}
/*
* Finally, if there is a FOR UPDATE/SHARE clause, add the LockRows node.
*/
if (parse->rowMarks)
{
result_plan = (Plan *) make_lockrows(result_plan,
parse->rowMarks);
}
/* Compute result-relations list if needed */
if (parse->resultRelation)
root->resultRelations = list_make1_int(parse->resultRelation);