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-rw-r--r--src/backend/commands/indexcmds.c38
-rw-r--r--src/backend/optimizer/path/joinpath.c9
-rw-r--r--src/backend/optimizer/path/joinrels.c60
-rw-r--r--src/backend/optimizer/plan/createplan.c46
-rw-r--r--src/backend/optimizer/util/paramassign.c39
5 files changed, 110 insertions, 82 deletions
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index c3ec2076a52..f2898fee5fc 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -2592,7 +2592,9 @@ makeObjectName(const char *name1, const char *name2, const char *label)
* constraint names.)
*
* Note: it is theoretically possible to get a collision anyway, if someone
- * else chooses the same name concurrently. This is fairly unlikely to be
+ * else chooses the same name concurrently. We shorten the race condition
+ * window by checking for conflicting relations using SnapshotDirty, but
+ * that doesn't close the window entirely. This is fairly unlikely to be
* a problem in practice, especially if one is holding an exclusive lock on
* the relation identified by name1. However, if choosing multiple names
* within a single command, you'd better create the new object and do
@@ -2608,15 +2610,45 @@ ChooseRelationName(const char *name1, const char *name2,
int pass = 0;
char *relname = NULL;
char modlabel[NAMEDATALEN];
+ SnapshotData SnapshotDirty;
+ Relation pgclassrel;
+
+ /* prepare to search pg_class with a dirty snapshot */
+ InitDirtySnapshot(SnapshotDirty);
+ pgclassrel = table_open(RelationRelationId, AccessShareLock);
/* try the unmodified label first */
strlcpy(modlabel, label, sizeof(modlabel));
for (;;)
{
+ ScanKeyData key[2];
+ SysScanDesc scan;
+ bool collides;
+
relname = makeObjectName(name1, name2, modlabel);
- if (!OidIsValid(get_relname_relid(relname, namespaceid)))
+ /* is there any conflicting relation name? */
+ ScanKeyInit(&key[0],
+ Anum_pg_class_relname,
+ BTEqualStrategyNumber, F_NAMEEQ,
+ CStringGetDatum(relname));
+ ScanKeyInit(&key[1],
+ Anum_pg_class_relnamespace,
+ BTEqualStrategyNumber, F_OIDEQ,
+ ObjectIdGetDatum(namespaceid));
+
+ scan = systable_beginscan(pgclassrel, ClassNameNspIndexId,
+ true /* indexOK */ ,
+ &SnapshotDirty,
+ 2, key);
+
+ collides = HeapTupleIsValid(systable_getnext(scan));
+
+ systable_endscan(scan);
+
+ /* break out of loop if no conflict */
+ if (!collides)
{
if (!isconstraint ||
!ConstraintNameExists(relname, namespaceid))
@@ -2628,6 +2660,8 @@ ChooseRelationName(const char *name1, const char *name2,
snprintf(modlabel, sizeof(modlabel), "%s%d", label, ++pass);
}
+ table_close(pgclassrel, AccessShareLock);
+
return relname;
}
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index 26f0336f1e4..7aa8f5d799c 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -876,16 +876,13 @@ try_nestloop_path(PlannerInfo *root,
/*
* Check to see if proposed path is still parameterized, and reject if the
* parameterization wouldn't be sensible --- unless allow_star_schema_join
- * says to allow it anyway. Also, we must reject if have_dangerous_phv
- * doesn't like the look of it, which could only happen if the nestloop is
- * still parameterized.
+ * says to allow it anyway.
*/
required_outer = calc_nestloop_required_outer(outerrelids, outer_paramrels,
innerrelids, inner_paramrels);
if (required_outer &&
- ((!bms_overlap(required_outer, extra->param_source_rels) &&
- !allow_star_schema_join(root, outerrelids, inner_paramrels)) ||
- have_dangerous_phv(root, outerrelids, inner_paramrels)))
+ !bms_overlap(required_outer, extra->param_source_rels) &&
+ !allow_star_schema_join(root, outerrelids, inner_paramrels))
{
/* Waste no memory when we reject a path here */
bms_free(required_outer);
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index 60d65762b5d..aad41b94009 100644
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -565,9 +565,6 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
* Also, if the lateral reference is only indirect, we should reject
* the join; whatever rel(s) the reference chain goes through must be
* joined to first.
- *
- * Another case that might keep us from building a valid plan is the
- * implementation restriction described by have_dangerous_phv().
*/
lateral_fwd = bms_overlap(rel1->relids, rel2->lateral_relids);
lateral_rev = bms_overlap(rel2->relids, rel1->lateral_relids);
@@ -584,9 +581,6 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
/* check there is a direct reference from rel2 to rel1 */
if (!bms_overlap(rel1->relids, rel2->direct_lateral_relids))
return false; /* only indirect refs, so reject */
- /* check we won't have a dangerous PHV */
- if (have_dangerous_phv(root, rel1->relids, rel2->lateral_relids))
- return false; /* might be unable to handle required PHV */
}
else if (lateral_rev)
{
@@ -599,9 +593,6 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
/* check there is a direct reference from rel1 to rel2 */
if (!bms_overlap(rel2->relids, rel1->direct_lateral_relids))
return false; /* only indirect refs, so reject */
- /* check we won't have a dangerous PHV */
- if (have_dangerous_phv(root, rel2->relids, rel1->lateral_relids))
- return false; /* might be unable to handle required PHV */
}
/*
@@ -1279,57 +1270,6 @@ has_legal_joinclause(PlannerInfo *root, RelOptInfo *rel)
/*
- * There's a pitfall for creating parameterized nestloops: suppose the inner
- * rel (call it A) has a parameter that is a PlaceHolderVar, and that PHV's
- * minimum eval_at set includes the outer rel (B) and some third rel (C).
- * We might think we could create a B/A nestloop join that's parameterized by
- * C. But we would end up with a plan in which the PHV's expression has to be
- * evaluated as a nestloop parameter at the B/A join; and the executor is only
- * set up to handle simple Vars as NestLoopParams. Rather than add complexity
- * and overhead to the executor for such corner cases, it seems better to
- * forbid the join. (Note that we can still make use of A's parameterized
- * path with pre-joined B+C as the outer rel. have_join_order_restriction()
- * ensures that we will consider making such a join even if there are not
- * other reasons to do so.)
- *
- * So we check whether any PHVs used in the query could pose such a hazard.
- * We don't have any simple way of checking whether a risky PHV would actually
- * be used in the inner plan, and the case is so unusual that it doesn't seem
- * worth working very hard on it.
- *
- * This needs to be checked in two places. If the inner rel's minimum
- * parameterization would trigger the restriction, then join_is_legal() should
- * reject the join altogether, because there will be no workable paths for it.
- * But joinpath.c has to check again for every proposed nestloop path, because
- * the inner path might have more than the minimum parameterization, causing
- * some PHV to be dangerous for it that otherwise wouldn't be.
- */
-bool
-have_dangerous_phv(PlannerInfo *root,
- Relids outer_relids, Relids inner_params)
-{
- ListCell *lc;
-
- foreach(lc, root->placeholder_list)
- {
- PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc);
-
- if (!bms_is_subset(phinfo->ph_eval_at, inner_params))
- continue; /* ignore, could not be a nestloop param */
- if (!bms_overlap(phinfo->ph_eval_at, outer_relids))
- continue; /* ignore, not relevant to this join */
- if (bms_is_subset(phinfo->ph_eval_at, outer_relids))
- continue; /* safe, it can be eval'd within outerrel */
- /* Otherwise, it's potentially unsafe, so reject the join */
- return true;
- }
-
- /* OK to perform the join */
- return false;
-}
-
-
-/*
* is_dummy_rel --- has relation been proven empty?
*/
bool
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 4ad30b7627e..8baf36ba4b7 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -4348,9 +4348,11 @@ create_nestloop_plan(PlannerInfo *root,
List *joinrestrictclauses = best_path->jpath.joinrestrictinfo;
List *joinclauses;
List *otherclauses;
- Relids outerrelids;
List *nestParams;
+ List *outer_tlist;
+ bool outer_parallel_safe;
Relids saveOuterRels = root->curOuterRels;
+ ListCell *lc;
/*
* If the inner path is parameterized by the topmost parent of the outer
@@ -4412,9 +4414,47 @@ create_nestloop_plan(PlannerInfo *root,
* Identify any nestloop parameters that should be supplied by this join
* node, and remove them from root->curOuterParams.
*/
- outerrelids = best_path->jpath.outerjoinpath->parent->relids;
- nestParams = identify_current_nestloop_params(root, outerrelids);
+ nestParams = identify_current_nestloop_params(root,
+ best_path->jpath.outerjoinpath);
+
+ /*
+ * While nestloop parameters that are Vars had better be available from
+ * the outer_plan already, there are edge cases where nestloop parameters
+ * that are PHVs won't be. In such cases we must add them to the
+ * outer_plan's tlist, since the executor's NestLoopParam machinery
+ * requires the params to be simple outer-Var references to that tlist.
+ */
+ outer_tlist = outer_plan->targetlist;
+ outer_parallel_safe = outer_plan->parallel_safe;
+ foreach(lc, nestParams)
+ {
+ NestLoopParam *nlp = (NestLoopParam *) lfirst(lc);
+ TargetEntry *tle;
+
+ if (IsA(nlp->paramval, Var))
+ continue; /* nothing to do for simple Vars */
+ if (tlist_member((Expr *) nlp->paramval, outer_tlist))
+ continue; /* already available */
+
+ /* Make a shallow copy of outer_tlist, if we didn't already */
+ if (outer_tlist == outer_plan->targetlist)
+ outer_tlist = list_copy(outer_tlist);
+ /* ... and add the needed expression */
+ tle = makeTargetEntry((Expr *) copyObject(nlp->paramval),
+ list_length(outer_tlist) + 1,
+ NULL,
+ true);
+ outer_tlist = lappend(outer_tlist, tle);
+ /* ... and track whether tlist is (still) parallel-safe */
+ if (outer_parallel_safe)
+ outer_parallel_safe = is_parallel_safe(root,
+ (Node *) nlp->paramval);
+ }
+ if (outer_tlist != outer_plan->targetlist)
+ outer_plan = change_plan_targetlist(outer_plan, outer_tlist,
+ outer_parallel_safe);
+ /* And finally, we can build the join plan node */
join_plan = make_nestloop(tlist,
joinclauses,
otherclauses,
diff --git a/src/backend/optimizer/util/paramassign.c b/src/backend/optimizer/util/paramassign.c
index 3bd3ce37c8f..9836abf9479 100644
--- a/src/backend/optimizer/util/paramassign.c
+++ b/src/backend/optimizer/util/paramassign.c
@@ -600,7 +600,7 @@ process_subquery_nestloop_params(PlannerInfo *root, List *subplan_params)
/*
* Identify any NestLoopParams that should be supplied by a NestLoop plan
- * node with the specified lefthand rels. Remove them from the active
+ * node with the specified lefthand input path. Remove them from the active
* root->curOuterParams list and return them as the result list.
*
* XXX Here we also hack up the returned Vars and PHVs so that they do not
@@ -626,11 +626,26 @@ process_subquery_nestloop_params(PlannerInfo *root, List *subplan_params)
* subquery, which'd be unduly expensive.
*/
List *
-identify_current_nestloop_params(PlannerInfo *root, Relids leftrelids)
+identify_current_nestloop_params(PlannerInfo *root, Path *leftpath)
{
List *result;
+ Relids leftrelids = leftpath->parent->relids;
+ Relids outerrelids = PATH_REQ_OUTER(leftpath);
+ Relids allleftrelids;
ListCell *cell;
+ /*
+ * We'll be able to evaluate a PHV in the lefthand path if it uses the
+ * lefthand rels plus any available required-outer rels. But don't do so
+ * if it uses *only* required-outer rels; in that case it should be
+ * evaluated higher in the tree. For Vars, no such hair-splitting is
+ * necessary since they depend on only one relid.
+ */
+ if (outerrelids)
+ allleftrelids = bms_union(leftrelids, outerrelids);
+ else
+ allleftrelids = leftrelids;
+
result = NIL;
foreach(cell, root->curOuterParams)
{
@@ -653,18 +668,20 @@ identify_current_nestloop_params(PlannerInfo *root, Relids leftrelids)
leftrelids);
result = lappend(result, nlp);
}
- else if (IsA(nlp->paramval, PlaceHolderVar) &&
- bms_is_subset(find_placeholder_info(root,
- (PlaceHolderVar *) nlp->paramval)->ph_eval_at,
- leftrelids))
+ else if (IsA(nlp->paramval, PlaceHolderVar))
{
PlaceHolderVar *phv = (PlaceHolderVar *) nlp->paramval;
+ Relids eval_at = find_placeholder_info(root, phv)->ph_eval_at;
- root->curOuterParams = foreach_delete_current(root->curOuterParams,
- cell);
- phv->phnullingrels = bms_intersect(phv->phnullingrels,
- leftrelids);
- result = lappend(result, nlp);
+ if (bms_is_subset(eval_at, allleftrelids) &&
+ bms_overlap(eval_at, leftrelids))
+ {
+ root->curOuterParams = foreach_delete_current(root->curOuterParams,
+ cell);
+ phv->phnullingrels = bms_intersect(phv->phnullingrels,
+ leftrelids);
+ result = lappend(result, nlp);
+ }
}
}
return result;
generated by cgit v1.2.3 (git 2.25.1) at 2025-06-21 04:47:12 +0000