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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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114
src/backend/optimizer/plan/subselect.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.155 2009/10/12 18:10:48 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.156 2009/10/26 02:26:35 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -77,7 +77,8 @@ static Node *process_sublinks_mutator(Node *node,
process_sublinks_context *context);
static Bitmapset *finalize_plan(PlannerInfo *root,
Plan *plan,
Bitmapset *valid_params);
Bitmapset *valid_params,
Bitmapset *scan_params);
static bool finalize_primnode(Node *node, finalize_primnode_context *context);
@ -215,10 +216,14 @@ generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod)
}
/*
* Assign a (nonnegative) PARAM_EXEC ID for a recursive query's worktable.
* Assign a (nonnegative) PARAM_EXEC ID for a special parameter (one that
* is not actually used to carry a value at runtime). Such parameters are
* used for special runtime signaling purposes, such as connecting a
* recursive union node to its worktable scan node or forcing plan
* re-evaluation within the EvalPlanQual mechanism.
*/
int
SS_assign_worktable_param(PlannerInfo *root)
SS_assign_special_param(PlannerInfo *root)
{
Param *param;
@ -335,7 +340,7 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
/* And convert to SubPlan or InitPlan format. */
result = build_subplan(root, plan,
subroot->parse->rtable, subroot->parse->rowMarks,
subroot->parse->rtable, subroot->rowMarks,
subLinkType, testexpr, true, isTopQual);
/*
@ -377,7 +382,7 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
/* OK, convert to SubPlan format. */
hashplan = (SubPlan *) build_subplan(root, plan,
subroot->parse->rtable,
subroot->parse->rowMarks,
subroot->rowMarks,
ANY_SUBLINK, newtestexpr,
false, true);
/* Check we got what we expected */
@ -949,7 +954,7 @@ SS_process_ctes(PlannerInfo *root)
root->glob->subrtables = lappend(root->glob->subrtables,
subroot->parse->rtable);
root->glob->subrowmarks = lappend(root->glob->subrowmarks,
subroot->parse->rowMarks);
subroot->rowMarks);
splan->plan_id = list_length(root->glob->subplans);
root->init_plans = lappend(root->init_plans, splan);
@ -1702,7 +1707,8 @@ process_sublinks_mutator(Node *node, process_sublinks_context *context)
}
/*
* SS_finalize_plan - do final sublink processing for a completed Plan.
* SS_finalize_plan - do final sublink and parameter processing for a
* completed Plan.
*
* This recursively computes the extParam and allParam sets for every Plan
* node in the given plan tree. It also optionally attaches any previously
@ -1751,7 +1757,8 @@ SS_finalize_plan(PlannerInfo *root, Plan *plan, bool attach_initplans)
* output parameters of any initPlans. (We do not include output
* parameters of regular subplans. Those should only appear within the
* testexpr of SubPlan nodes, and are taken care of locally within
* finalize_primnode.)
* finalize_primnode. Likewise, special parameters that are generated
* by nodes such as ModifyTable are handled within finalize_plan.)
*
* Note: this is a bit overly generous since some parameters of upper
* query levels might belong to query subtrees that don't include this
@ -1772,14 +1779,11 @@ SS_finalize_plan(PlannerInfo *root, Plan *plan, bool attach_initplans)
paramid++;
}
/* Also include the recursion working table, if any */
if (root->wt_param_id >= 0)
valid_params = bms_add_member(valid_params, root->wt_param_id);
/*
* Now recurse through plan tree.
*/
(void) finalize_plan(root, plan, valid_params);
(void) finalize_plan(root, plan, valid_params, NULL);
bms_free(valid_params);
@ -1819,19 +1823,28 @@ SS_finalize_plan(PlannerInfo *root, Plan *plan, bool attach_initplans)
/*
* Recursive processing of all nodes in the plan tree
*
* valid_params is the set of param IDs considered valid to reference in
* this plan node or its children.
* scan_params is a set of param IDs to force scan plan nodes to reference.
* This is for EvalPlanQual support, and is always NULL at the top of the
* recursion.
*
* The return value is the computed allParam set for the given Plan node.
* This is just an internal notational convenience.
*/
static Bitmapset *
finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params,
Bitmapset *scan_params)
{
finalize_primnode_context context;
int locally_added_param;
if (plan == NULL)
return NULL;
context.root = root;
context.paramids = NULL; /* initialize set to empty */
locally_added_param = -1; /* there isn't one */
/*
* When we call finalize_primnode, context.paramids sets are automatically
@ -1852,6 +1865,10 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
&context);
break;
case T_SeqScan:
context.paramids = bms_add_members(context.paramids, scan_params);
break;
case T_IndexScan:
finalize_primnode((Node *) ((IndexScan *) plan)->indexqual,
&context);
@ -1860,6 +1877,7 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
* we need not look at indexqualorig, since it will have the same
* param references as indexqual.
*/
context.paramids = bms_add_members(context.paramids, scan_params);
break;
case T_BitmapIndexScan:
@ -1875,11 +1893,13 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
case T_BitmapHeapScan:
finalize_primnode((Node *) ((BitmapHeapScan *) plan)->bitmapqualorig,
&context);
context.paramids = bms_add_members(context.paramids, scan_params);
break;
case T_TidScan:
finalize_primnode((Node *) ((TidScan *) plan)->tidquals,
&context);
context.paramids = bms_add_members(context.paramids, scan_params);
break;
case T_SubqueryScan:
@ -1893,16 +1913,20 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
*/
context.paramids = bms_add_members(context.paramids,
((SubqueryScan *) plan)->subplan->extParam);
/* We need scan_params too, though */
context.paramids = bms_add_members(context.paramids, scan_params);
break;
case T_FunctionScan:
finalize_primnode(((FunctionScan *) plan)->funcexpr,
&context);
context.paramids = bms_add_members(context.paramids, scan_params);
break;
case T_ValuesScan:
finalize_primnode((Node *) ((ValuesScan *) plan)->values_lists,
&context);
context.paramids = bms_add_members(context.paramids, scan_params);
break;
case T_CteScan:
@ -1934,6 +1958,9 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
bms_add_member(context.paramids,
((CteScan *) plan)->cteParam);
#endif
context.paramids = bms_add_members(context.paramids,
scan_params);
}
break;
@ -1941,21 +1968,30 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
context.paramids =
bms_add_member(context.paramids,
((WorkTableScan *) plan)->wtParam);
context.paramids = bms_add_members(context.paramids, scan_params);
break;
case T_ModifyTable:
{
ModifyTable *mtplan = (ModifyTable *) plan;
ListCell *l;
finalize_primnode((Node *) ((ModifyTable *) plan)->returningLists,
/* Force descendant scan nodes to reference epqParam */
locally_added_param = mtplan->epqParam;
valid_params = bms_add_member(bms_copy(valid_params),
locally_added_param);
scan_params = bms_add_member(bms_copy(scan_params),
locally_added_param);
finalize_primnode((Node *) mtplan->returningLists,
&context);
foreach(l, ((ModifyTable *) plan)->plans)
foreach(l, mtplan->plans)
{
context.paramids =
bms_add_members(context.paramids,
finalize_plan(root,
(Plan *) lfirst(l),
valid_params));
valid_params,
scan_params));
}
}
break;
@ -1970,7 +2006,8 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
bms_add_members(context.paramids,
finalize_plan(root,
(Plan *) lfirst(l),
valid_params));
valid_params,
scan_params));
}
}
break;
@ -1985,7 +2022,8 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
bms_add_members(context.paramids,
finalize_plan(root,
(Plan *) lfirst(l),
valid_params));
valid_params,
scan_params));
}
}
break;
@ -2000,7 +2038,8 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
bms_add_members(context.paramids,
finalize_plan(root,
(Plan *) lfirst(l),
valid_params));
valid_params,
scan_params));
}
}
break;
@ -2032,16 +2071,30 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
break;
case T_RecursiveUnion:
/* child nodes are allowed to reference wtParam */
locally_added_param = ((RecursiveUnion *) plan)->wtParam;
valid_params = bms_add_member(bms_copy(valid_params),
locally_added_param);
/* wtParam does *not* get added to scan_params */
break;
case T_LockRows:
/* Force descendant scan nodes to reference epqParam */
locally_added_param = ((LockRows *) plan)->epqParam;
valid_params = bms_add_member(bms_copy(valid_params),
locally_added_param);
scan_params = bms_add_member(bms_copy(scan_params),
locally_added_param);
break;
case T_Hash:
case T_Agg:
case T_WindowAgg:
case T_SeqScan:
case T_Material:
case T_Sort:
case T_Unique:
case T_SetOp:
case T_Group:
case T_LockRows:
break;
default:
@ -2053,20 +2106,25 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
context.paramids = bms_add_members(context.paramids,
finalize_plan(root,
plan->lefttree,
valid_params));
valid_params,
scan_params));
context.paramids = bms_add_members(context.paramids,
finalize_plan(root,
plan->righttree,
valid_params));
valid_params,
scan_params));
/*
* RecursiveUnion *generates* its worktable param, so don't bubble that up
* Any locally generated parameter doesn't count towards its generating
* plan node's external dependencies. (Note: if we changed valid_params
* and/or scan_params, we leak those bitmapsets; not worth the notational
* trouble to clean them up.)
*/
if (IsA(plan, RecursiveUnion))
if (locally_added_param >= 0)
{
context.paramids = bms_del_member(context.paramids,
((RecursiveUnion *) plan)->wtParam);
locally_added_param);
}
/* Now we have all the paramids */
@ -2199,7 +2257,7 @@ SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan,
root->glob->subrtables = lappend(root->glob->subrtables,
root->parse->rtable);
root->glob->subrowmarks = lappend(root->glob->subrowmarks,
root->parse->rowMarks);
root->rowMarks);
/*
* Create a SubPlan node and add it to the outer list of InitPlans. Note