database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-08 11:42:09 +03:00
Code Activity

Re-implement EvalPlanQual processing to improve its performance and eliminate

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

227
src/backend/optimizer/plan/planner.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.259 2009/10/12 18:10:48 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.260 2009/10/26 02:26:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -35,6 +35,7 @@
#ifdef OPTIMIZER_DEBUG
#include "nodes/print.h"
#endif
#include "parser/analyze.h"
#include "parser/parse_expr.h"
#include "parser/parse_oper.h"
#include "parser/parsetree.h"
@ -63,6 +64,7 @@ static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode);
static Plan *inheritance_planner(PlannerInfo *root);
static Plan *grouping_planner(PlannerInfo *root, double tuple_fraction);
static bool is_dummy_plan(Plan *plan);
static void preprocess_rowmarks(PlannerInfo *root);
static double preprocess_limit(PlannerInfo *root,
double tuple_fraction,
int64 *offset_est, int64 *count_est);
@ -159,7 +161,6 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
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 */
@ -209,7 +210,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
Assert(glob->finalrowmarks == NIL);
top_plan = set_plan_references(glob, top_plan,
root->parse->rtable,
root->parse->rowMarks);
root->rowMarks);
/* ... and the subplans (both regular subplans and initplans) */
Assert(list_length(glob->subplans) == list_length(glob->subrtables));
Assert(list_length(glob->subplans) == list_length(glob->subrowmarks));
@ -301,10 +302,11 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
root->cte_plan_ids = NIL;
root->eq_classes = NIL;
root->append_rel_list = NIL;
root->rowMarks = NIL;
root->hasRecursion = hasRecursion;
if (hasRecursion)
root->wt_param_id = SS_assign_worktable_param(root);
root->wt_param_id = SS_assign_special_param(root);
else
root->wt_param_id = -1;
root->non_recursive_plan = NULL;
@ -364,19 +366,12 @@ 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.
* Preprocess RowMark information. We need to do this after subquery
* pullup (so that all non-inherited RTEs are present) and before
* inheritance expansion (so that the info is available for
* expand_inherited_tables to examine and modify).
*/
foreach(l, parse->rowMarks)
{
RowMarkClause *rc = (RowMarkClause *) lfirst(l);
rc->rowmarkId = ++(root->glob->lastRowmarkId);
}
preprocess_rowmarks(root);
/*
* Expand any rangetable entries that are inheritance sets into "append
@ -512,14 +507,15 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
/* If it's not SELECT, we need a ModifyTable node */
if (parse->commandType != CMD_SELECT)
{
List *returningLists;
List *rowMarks;
/*
* Deal with the RETURNING clause if any. It's convenient to pass
* the returningList through setrefs.c now rather than at top
* level (if we waited, handling inherited UPDATE/DELETE would be
* much harder).
*/
List *returningLists;
if (parse->returningList)
{
List *rlist;
@ -534,20 +530,32 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
else
returningLists = NIL;
/*
* If there was a FOR UPDATE/SHARE clause, the LockRows node will
* have dealt with fetching non-locked marked rows, else we need
* to have ModifyTable do that.
*/
if (parse->rowMarks)
rowMarks = NIL;
else
rowMarks = root->rowMarks;
plan = (Plan *) make_modifytable(parse->commandType,
copyObject(root->resultRelations),
list_make1(plan),
returningLists);
returningLists,
rowMarks,
SS_assign_special_param(root));
}
}
/*
* If any subplans were generated, or if we're inside a subplan, build
* initPlan list and extParam/allParam sets for plan nodes, and attach the
* initPlans to the top plan node.
* If any subplans were generated, or if there are any parameters to worry
* about, build initPlan list and extParam/allParam sets for plan nodes,
* and attach the initPlans to the top plan node.
*/
if (list_length(glob->subplans) != num_old_subplans ||
root->query_level > 1)
root->glob->paramlist != NIL)
SS_finalize_plan(root, plan, true);
/* Return internal info if caller wants it */
@ -701,6 +709,7 @@ inheritance_planner(PlannerInfo *root)
List *resultRelations = NIL;
List *returningLists = NIL;
List *rtable = NIL;
List *rowMarks;
List *tlist;
PlannerInfo subroot;
ListCell *l;
@ -797,11 +806,23 @@ inheritance_planner(PlannerInfo *root)
*/
parse->rtable = rtable;
/*
* If there was a FOR UPDATE/SHARE clause, the LockRows node will
* have dealt with fetching non-locked marked rows, else we need
* to have ModifyTable do that.
*/
if (parse->rowMarks)
rowMarks = NIL;
else
rowMarks = root->rowMarks;
/* And last, tack on a ModifyTable node to do the UPDATE/DELETE work */
return (Plan *) make_modifytable(parse->commandType,
copyObject(root->resultRelations),
subplans,
returningLists);
returningLists,
rowMarks,
SS_assign_special_param(root));
}
/*--------------------
@ -1630,11 +1651,15 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
/*
* Finally, if there is a FOR UPDATE/SHARE clause, add the LockRows node.
* (Note: we intentionally test parse->rowMarks not root->rowMarks here.
* If there are only non-locking rowmarks, they should be handled by
* the ModifyTable node instead.)
*/
if (parse->rowMarks)
{
result_plan = (Plan *) make_lockrows(result_plan,
parse->rowMarks);
root->rowMarks,
SS_assign_special_param(root));
}
/* Compute result-relations list if needed */
@ -1681,6 +1706,158 @@ is_dummy_plan(Plan *plan)
return false;
}
/*
* Create a bitmapset of the RT indexes of live base relations
*
* Helper for preprocess_rowmarks ... at this point in the proceedings,
* the only good way to distinguish baserels from appendrel children
* is to see what is in the join tree.
*/
static Bitmapset *
get_base_rel_indexes(Node *jtnode)
{
Bitmapset *result;
if (jtnode == NULL)
return NULL;
if (IsA(jtnode, RangeTblRef))
{
int varno = ((RangeTblRef *) jtnode)->rtindex;
result = bms_make_singleton(varno);
}
else if (IsA(jtnode, FromExpr))
{
FromExpr *f = (FromExpr *) jtnode;
ListCell *l;
result = NULL;
foreach(l, f->fromlist)
result = bms_join(result,
get_base_rel_indexes(lfirst(l)));
}
else if (IsA(jtnode, JoinExpr))
{
JoinExpr *j = (JoinExpr *) jtnode;
result = bms_join(get_base_rel_indexes(j->larg),
get_base_rel_indexes(j->rarg));
}
else
{
elog(ERROR, "unrecognized node type: %d",
(int) nodeTag(jtnode));
result = NULL; /* keep compiler quiet */
}
return result;
}
/*
* preprocess_rowmarks - set up PlanRowMarks if needed
*/
static void
preprocess_rowmarks(PlannerInfo *root)
{
Query *parse = root->parse;
Bitmapset *rels;
List *prowmarks;
ListCell *l;
int i;
if (parse->rowMarks)
{
/*
* We've got trouble if FOR UPDATE/SHARE appears inside grouping,
* since grouping renders a reference to individual tuple CTIDs
* invalid. This is also checked at parse time, but that's
* insufficient because of rule substitution, query pullup, etc.
*/
CheckSelectLocking(parse);
}
else
{
/*
* We only need rowmarks for UPDATE, DELETE, or FOR UPDATE/SHARE.
*/
if (parse->commandType != CMD_UPDATE &&
parse->commandType != CMD_DELETE)
return;
}
/*
* We need to have rowmarks for all base relations except the target.
* We make a bitmapset of all base rels and then remove the items we
* don't need or have FOR UPDATE/SHARE marks for.
*/
rels = get_base_rel_indexes((Node *) parse->jointree);
if (parse->resultRelation)
rels = bms_del_member(rels, parse->resultRelation);
/*
* Convert RowMarkClauses to PlanRowMark representation.
*
* Note: currently, it is syntactically impossible to have FOR UPDATE
* applied to an update/delete target rel. If that ever becomes
* possible, we should drop the target from the PlanRowMark list.
*/
prowmarks = NIL;
foreach(l, parse->rowMarks)
{
RowMarkClause *rc = (RowMarkClause *) lfirst(l);
PlanRowMark *newrc = makeNode(PlanRowMark);
Assert(rc->rti != parse->resultRelation);
rels = bms_del_member(rels, rc->rti);
newrc->rti = newrc->prti = rc->rti;
if (rc->forUpdate)
newrc->markType = ROW_MARK_EXCLUSIVE;
else
newrc->markType = ROW_MARK_SHARE;
newrc->noWait = rc->noWait;
newrc->isParent = false;
/* attnos will be assigned in preprocess_targetlist */
newrc->ctidAttNo = InvalidAttrNumber;
newrc->toidAttNo = InvalidAttrNumber;
newrc->wholeAttNo = InvalidAttrNumber;
prowmarks = lappend(prowmarks, newrc);
}
/*
* Now, add rowmarks for any non-target, non-locked base relations.
*/
i = 0;
foreach(l, parse->rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
PlanRowMark *newrc;
i++;
if (!bms_is_member(i, rels))
continue;
newrc = makeNode(PlanRowMark);
newrc->rti = newrc->prti = i;
/* real tables support REFERENCE, anything else needs COPY */
if (rte->rtekind == RTE_RELATION)
newrc->markType = ROW_MARK_REFERENCE;
else
newrc->markType = ROW_MARK_COPY;
newrc->noWait = false; /* doesn't matter */
newrc->isParent = false;
/* attnos will be assigned in preprocess_targetlist */
newrc->ctidAttNo = InvalidAttrNumber;
newrc->toidAttNo = InvalidAttrNumber;
newrc->wholeAttNo = InvalidAttrNumber;
prowmarks = lappend(prowmarks, newrc);
}
root->rowMarks = prowmarks;
}
/*
* preprocess_limit - do pre-estimation for LIMIT and/or OFFSET clauses
*