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-rw-r--r--src/backend/optimizer/plan/createplan.c34
-rw-r--r--src/backend/optimizer/util/paramassign.c84
-rw-r--r--src/backend/optimizer/util/placeholder.c40
-rw-r--r--src/include/optimizer/paramassign.h3
-rw-r--r--src/include/optimizer/placeholder.h2
-rw-r--r--src/test/regress/expected/join.out158
-rw-r--r--src/test/regress/sql/join.sql46
7 files changed, 330 insertions, 37 deletions
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 8baf36ba4b7..0b61aef962c 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -4344,6 +4344,7 @@ create_nestloop_plan(PlannerInfo *root,
NestLoop *join_plan;
Plan *outer_plan;
Plan *inner_plan;
+ Relids outerrelids;
List *tlist = build_path_tlist(root, &best_path->jpath.path);
List *joinrestrictclauses = best_path->jpath.joinrestrictinfo;
List *joinclauses;
@@ -4374,8 +4375,8 @@ create_nestloop_plan(PlannerInfo *root,
outer_plan = create_plan_recurse(root, best_path->jpath.outerjoinpath, 0);
/* For a nestloop, include outer relids in curOuterRels for inner side */
- root->curOuterRels = bms_union(root->curOuterRels,
- best_path->jpath.outerjoinpath->parent->relids);
+ outerrelids = best_path->jpath.outerjoinpath->parent->relids;
+ root->curOuterRels = bms_union(root->curOuterRels, outerrelids);
inner_plan = create_plan_recurse(root, best_path->jpath.innerjoinpath, 0);
@@ -4415,7 +4416,8 @@ create_nestloop_plan(PlannerInfo *root,
* node, and remove them from root->curOuterParams.
*/
nestParams = identify_current_nestloop_params(root,
- best_path->jpath.outerjoinpath);
+ outerrelids,
+ PATH_REQ_OUTER((Path *) best_path));
/*
* While nestloop parameters that are Vars had better be available from
@@ -4423,32 +4425,50 @@ create_nestloop_plan(PlannerInfo *root,
* 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.
+ * (This is cheating a little bit, because the outer path's required-outer
+ * relids might not be enough to allow evaluating such a PHV. But in
+ * practice, if we could have evaluated the PHV at the nestloop node, we
+ * can do so in the outer plan too.)
*/
outer_tlist = outer_plan->targetlist;
outer_parallel_safe = outer_plan->parallel_safe;
foreach(lc, nestParams)
{
NestLoopParam *nlp = (NestLoopParam *) lfirst(lc);
+ PlaceHolderVar *phv;
TargetEntry *tle;
if (IsA(nlp->paramval, Var))
continue; /* nothing to do for simple Vars */
- if (tlist_member((Expr *) nlp->paramval, outer_tlist))
+ /* Otherwise it must be a PHV */
+ phv = castNode(PlaceHolderVar, nlp->paramval);
+
+ if (tlist_member((Expr *) phv, outer_tlist))
continue; /* already available */
+ /*
+ * It's possible that nestloop parameter PHVs selected to evaluate
+ * here contain references to surviving root->curOuterParams items
+ * (that is, they reference values that will be supplied by some
+ * higher-level nestloop). Those need to be converted to Params now.
+ * Note: it's safe to do this after the tlist_member() check, because
+ * equal() won't pay attention to phv->phexpr.
+ */
+ phv->phexpr = (Expr *) replace_nestloop_params(root,
+ (Node *) phv->phexpr);
+
/* 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),
+ tle = makeTargetEntry((Expr *) copyObject(phv),
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);
+ outer_parallel_safe = is_parallel_safe(root, (Node *) phv);
}
if (outer_tlist != outer_plan->targetlist)
outer_plan = change_plan_targetlist(outer_plan, outer_tlist,
diff --git a/src/backend/optimizer/util/paramassign.c b/src/backend/optimizer/util/paramassign.c
index 9836abf9479..4c13c5931b4 100644
--- a/src/backend/optimizer/util/paramassign.c
+++ b/src/backend/optimizer/util/paramassign.c
@@ -599,38 +599,31 @@ 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 input path. Remove them from the active
- * root->curOuterParams list and return them as the result list.
+ * Identify any NestLoopParams that should be supplied by a NestLoop
+ * plan node with the specified lefthand rels and required-outer rels.
+ * 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
- * contain nullingrel sets exceeding what is available from the outer side.
- * This is needed if we have applied outer join identity 3,
- * (A leftjoin B on (Pab)) leftjoin C on (Pb*c)
- * = A leftjoin (B leftjoin C on (Pbc)) on (Pab)
- * and C contains lateral references to B. It's still safe to apply the
- * identity, but the parser will have created those references in the form
- * "b*" (i.e., with varnullingrels listing the A/B join), while what we will
- * have available from the nestloop's outer side is just "b". We deal with
- * that here by stripping the nullingrels down to what is available from the
- * outer side according to leftrelids.
- *
- * That fixes matters for the case of forward application of identity 3.
- * If the identity was applied in the reverse direction, we will have
- * parameter Vars containing too few nullingrel bits rather than too many.
- * Currently, that causes no problems because setrefs.c applies only a
- * subset check to nullingrels in NestLoopParams, but we'd have to work
- * harder if we ever want to tighten that check. This is all pretty annoying
- * because it greatly weakens setrefs.c's cross-check, but the alternative
+ * Vars and PHVs appearing in the result list must have nullingrel sets
+ * that could validly appear in the lefthand rel's output. Ordinarily that
+ * would be true already, but if we have applied outer join identity 3,
+ * there could be more or fewer nullingrel bits in the nodes appearing in
+ * curOuterParams than are in the nominal leftrelids. We deal with that by
+ * forcing their nullingrel sets to include exactly the outer-join relids
+ * that appear in leftrelids and can null the respective Var or PHV.
+ * This fix is a bit ad-hoc and intellectually unsatisfactory, because it's
+ * essentially jumping to the conclusion that we've placed evaluation of
+ * the nestloop parameters correctly, and thus it defeats the intent of the
+ * subsequent nullingrel cross-checks in setrefs.c. But the alternative
* seems to be to generate multiple versions of each laterally-parameterized
* subquery, which'd be unduly expensive.
*/
List *
-identify_current_nestloop_params(PlannerInfo *root, Path *leftpath)
+identify_current_nestloop_params(PlannerInfo *root,
+ Relids leftrelids,
+ Relids outerrelids)
{
List *result;
- Relids leftrelids = leftpath->parent->relids;
- Relids outerrelids = PATH_REQ_OUTER(leftpath);
Relids allleftrelids;
ListCell *cell;
@@ -661,25 +654,58 @@ identify_current_nestloop_params(PlannerInfo *root, Path *leftpath)
bms_is_member(nlp->paramval->varno, leftrelids))
{
Var *var = (Var *) nlp->paramval;
+ RelOptInfo *rel = root->simple_rel_array[var->varno];
root->curOuterParams = foreach_delete_current(root->curOuterParams,
cell);
- var->varnullingrels = bms_intersect(var->varnullingrels,
+ var->varnullingrels = bms_intersect(rel->nulling_relids,
leftrelids);
result = lappend(result, nlp);
}
else if (IsA(nlp->paramval, PlaceHolderVar))
{
PlaceHolderVar *phv = (PlaceHolderVar *) nlp->paramval;
- Relids eval_at = find_placeholder_info(root, phv)->ph_eval_at;
+ PlaceHolderInfo *phinfo = find_placeholder_info(root, phv);
+ Relids eval_at = phinfo->ph_eval_at;
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);
+
+ /*
+ * Deal with an edge case: if the PHV was pulled up out of a
+ * subquery and it contains a subquery that was originally
+ * pushed down from this query level, then that will still be
+ * represented as a SubLink, because SS_process_sublinks won't
+ * recurse into outer PHVs, so it didn't get transformed
+ * during expression preprocessing in the subquery. We need a
+ * version of the PHV that has a SubPlan, which we can get
+ * from the current query level's placeholder_list. This is
+ * quite grotty of course, but dealing with it earlier in the
+ * handling of subplan params would be just as grotty, and it
+ * might end up being a waste of cycles if we don't decide to
+ * treat the PHV as a NestLoopParam. (Perhaps that whole
+ * mechanism should be redesigned someday, but today is not
+ * that day.)
+ */
+ if (root->parse->hasSubLinks)
+ {
+ phv = copyObject(phinfo->ph_var);
+
+ /*
+ * The ph_var will have empty nullingrels, but that
+ * doesn't matter since we're about to overwrite
+ * phv->phnullingrels. Other fields should be OK already.
+ */
+ nlp->paramval = (Var *) phv;
+ }
+
+ phv->phnullingrels =
+ bms_intersect(get_placeholder_nulling_relids(root, phinfo),
+ leftrelids);
+
result = lappend(result, nlp);
}
}
diff --git a/src/backend/optimizer/util/placeholder.c b/src/backend/optimizer/util/placeholder.c
index 41a4c81e94a..e1cd00a72fb 100644
--- a/src/backend/optimizer/util/placeholder.c
+++ b/src/backend/optimizer/util/placeholder.c
@@ -545,3 +545,43 @@ contain_placeholder_references_walker(Node *node,
return expression_tree_walker(node, contain_placeholder_references_walker,
context);
}
+
+/*
+ * Compute the set of outer-join relids that can null a placeholder.
+ *
+ * This is analogous to RelOptInfo.nulling_relids for Vars, but we compute it
+ * on-the-fly rather than saving it somewhere. Currently the value is needed
+ * at most once per query, so there's little value in doing otherwise. If it
+ * ever gains more widespread use, perhaps we should cache the result in
+ * PlaceHolderInfo.
+ */
+Relids
+get_placeholder_nulling_relids(PlannerInfo *root, PlaceHolderInfo *phinfo)
+{
+ Relids result = NULL;
+ int relid = -1;
+
+ /*
+ * Form the union of all potential nulling OJs for each baserel included
+ * in ph_eval_at.
+ */
+ while ((relid = bms_next_member(phinfo->ph_eval_at, relid)) > 0)
+ {
+ RelOptInfo *rel = root->simple_rel_array[relid];
+
+ /* ignore the RTE_GROUP RTE */
+ if (relid == root->group_rtindex)
+ continue;
+
+ if (rel == NULL) /* must be an outer join */
+ {
+ Assert(bms_is_member(relid, root->outer_join_rels));
+ continue;
+ }
+ result = bms_add_members(result, rel->nulling_relids);
+ }
+
+ /* Now remove any OJs already included in ph_eval_at, and we're done. */
+ result = bms_del_members(result, phinfo->ph_eval_at);
+ return result;
+}
diff --git a/src/include/optimizer/paramassign.h b/src/include/optimizer/paramassign.h
index d30d20de299..bbf7214289b 100644
--- a/src/include/optimizer/paramassign.h
+++ b/src/include/optimizer/paramassign.h
@@ -30,7 +30,8 @@ extern Param *replace_nestloop_param_placeholdervar(PlannerInfo *root,
extern void process_subquery_nestloop_params(PlannerInfo *root,
List *subplan_params);
extern List *identify_current_nestloop_params(PlannerInfo *root,
- Path *leftpath);
+ Relids leftrelids,
+ Relids outerrelids);
extern Param *generate_new_exec_param(PlannerInfo *root, Oid paramtype,
int32 paramtypmod, Oid paramcollation);
extern int assign_special_exec_param(PlannerInfo *root);
diff --git a/src/include/optimizer/placeholder.h b/src/include/optimizer/placeholder.h
index d351045e2e0..db92d8861ba 100644
--- a/src/include/optimizer/placeholder.h
+++ b/src/include/optimizer/placeholder.h
@@ -30,5 +30,7 @@ extern void add_placeholders_to_joinrel(PlannerInfo *root, RelOptInfo *joinrel,
SpecialJoinInfo *sjinfo);
extern bool contain_placeholder_references_to(PlannerInfo *root, Node *clause,
int relid);
+extern Relids get_placeholder_nulling_relids(PlannerInfo *root,
+ PlaceHolderInfo *phinfo);
#endif /* PLACEHOLDER_H */
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index c292f04fdba..390aabfb34b 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -4119,6 +4119,164 @@ select * from int8_tbl t1
(16 rows)
rollback;
+-- ... not that the initial replacement didn't have some bugs too
+begin;
+create temp table t(i int primary key);
+explain (verbose, costs off)
+select * from t t1
+ left join (select 1 as x, * from t t2(i2)) t2ss on t1.i = t2ss.i2
+ left join t t3(i3) on false
+ left join t t4(i4) on t4.i4 > t2ss.x;
+ QUERY PLAN
+----------------------------------------------------------
+ Nested Loop Left Join
+ Output: t1.i, (1), t2.i2, i3, t4.i4
+ -> Nested Loop Left Join
+ Output: t1.i, t2.i2, (1), i3
+ Join Filter: false
+ -> Hash Left Join
+ Output: t1.i, t2.i2, (1)
+ Inner Unique: true
+ Hash Cond: (t1.i = t2.i2)
+ -> Seq Scan on pg_temp.t t1
+ Output: t1.i
+ -> Hash
+ Output: t2.i2, (1)
+ -> Seq Scan on pg_temp.t t2
+ Output: t2.i2, 1
+ -> Result
+ Output: i3
+ One-Time Filter: false
+ -> Memoize
+ Output: t4.i4
+ Cache Key: (1)
+ Cache Mode: binary
+ -> Index Only Scan using t_pkey on pg_temp.t t4
+ Output: t4.i4
+ Index Cond: (t4.i4 > (1))
+(25 rows)
+
+explain (verbose, costs off)
+select * from
+ (select k from
+ (select i, coalesce(i, j) as k from
+ (select i from t union all select 0)
+ join (select 1 as j limit 1) on i = j)
+ right join (select 2 as x) on true
+ join (select 3 as y) on i is not null
+ ),
+ lateral (select k as kl limit 1);
+ QUERY PLAN
+-------------------------------------------------------------------
+ Nested Loop
+ Output: COALESCE(t.i, (1)), ((COALESCE(t.i, (1))))
+ -> Limit
+ Output: 1
+ -> Result
+ Output: 1
+ -> Nested Loop
+ Output: t.i, ((COALESCE(t.i, (1))))
+ -> Result
+ Output: t.i, COALESCE(t.i, (1))
+ -> Append
+ -> Index Only Scan using t_pkey on pg_temp.t
+ Output: t.i
+ Index Cond: (t.i = (1))
+ -> Result
+ Output: 0
+ One-Time Filter: ((1) = 0)
+ -> Limit
+ Output: ((COALESCE(t.i, (1))))
+ -> Result
+ Output: (COALESCE(t.i, (1)))
+(21 rows)
+
+rollback;
+-- PHVs containing SubLinks are quite tricky to get right
+explain (verbose, costs off)
+select *
+from int8_tbl i8
+ inner join
+ (select (select true) as x
+ from int4_tbl i4, lateral (select i4.f1 as y limit 1) ss1
+ where i4.f1 = 0) ss2 on true
+ right join (select false as z) ss3 on true,
+ lateral (select i8.q2 as q2l where x limit 1) ss4
+where i8.q2 = 123;
+ QUERY PLAN
+----------------------------------------------------------------
+ Nested Loop
+ Output: i8.q1, i8.q2, (InitPlan 1).col1, false, (i8.q2)
+ InitPlan 1
+ -> Result
+ Output: true
+ InitPlan 2
+ -> Result
+ Output: true
+ -> Seq Scan on public.int4_tbl i4
+ Output: i4.f1
+ Filter: (i4.f1 = 0)
+ -> Nested Loop
+ Output: i8.q1, i8.q2, (i8.q2)
+ -> Subquery Scan on ss1
+ Output: ss1.y, (InitPlan 1).col1
+ -> Limit
+ Output: NULL::integer
+ -> Result
+ Output: NULL::integer
+ -> Nested Loop
+ Output: i8.q1, i8.q2, (i8.q2)
+ -> Seq Scan on public.int8_tbl i8
+ Output: i8.q1, i8.q2
+ Filter: (i8.q2 = 123)
+ -> Limit
+ Output: (i8.q2)
+ -> Result
+ Output: i8.q2
+ One-Time Filter: ((InitPlan 1).col1)
+(29 rows)
+
+explain (verbose, costs off)
+select *
+from int8_tbl i8
+ inner join
+ (select (select true) as x
+ from int4_tbl i4, lateral (select 1 as y limit 1) ss1
+ where i4.f1 = 0) ss2 on true
+ right join (select false as z) ss3 on true,
+ lateral (select i8.q2 as q2l where x limit 1) ss4
+where i8.q2 = 123;
+ QUERY PLAN
+----------------------------------------------------------------
+ Nested Loop
+ Output: i8.q1, i8.q2, (InitPlan 1).col1, false, (i8.q2)
+ InitPlan 1
+ -> Result
+ Output: true
+ InitPlan 2
+ -> Result
+ Output: true
+ -> Limit
+ Output: NULL::integer
+ -> Result
+ Output: NULL::integer
+ -> Nested Loop
+ Output: i8.q1, i8.q2, (i8.q2)
+ -> Seq Scan on public.int4_tbl i4
+ Output: i4.f1, (InitPlan 1).col1
+ Filter: (i4.f1 = 0)
+ -> Nested Loop
+ Output: i8.q1, i8.q2, (i8.q2)
+ -> Seq Scan on public.int8_tbl i8
+ Output: i8.q1, i8.q2
+ Filter: (i8.q2 = 123)
+ -> Limit
+ Output: (i8.q2)
+ -> Result
+ Output: i8.q2
+ One-Time Filter: ((InitPlan 1).col1)
+(27 rows)
+
-- Test proper handling of appendrel PHVs during useless-RTE removal
explain (costs off)
select * from
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index 88d2204e447..f6e7070db65 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1361,6 +1361,52 @@ select * from int8_tbl t1
on true;
rollback;
+-- ... not that the initial replacement didn't have some bugs too
+begin;
+create temp table t(i int primary key);
+
+explain (verbose, costs off)
+select * from t t1
+ left join (select 1 as x, * from t t2(i2)) t2ss on t1.i = t2ss.i2
+ left join t t3(i3) on false
+ left join t t4(i4) on t4.i4 > t2ss.x;
+
+explain (verbose, costs off)
+select * from
+ (select k from
+ (select i, coalesce(i, j) as k from
+ (select i from t union all select 0)
+ join (select 1 as j limit 1) on i = j)
+ right join (select 2 as x) on true
+ join (select 3 as y) on i is not null
+ ),
+ lateral (select k as kl limit 1);
+
+rollback;
+
+-- PHVs containing SubLinks are quite tricky to get right
+explain (verbose, costs off)
+select *
+from int8_tbl i8
+ inner join
+ (select (select true) as x
+ from int4_tbl i4, lateral (select i4.f1 as y limit 1) ss1
+ where i4.f1 = 0) ss2 on true
+ right join (select false as z) ss3 on true,
+ lateral (select i8.q2 as q2l where x limit 1) ss4
+where i8.q2 = 123;
+
+explain (verbose, costs off)
+select *
+from int8_tbl i8
+ inner join
+ (select (select true) as x
+ from int4_tbl i4, lateral (select 1 as y limit 1) ss1
+ where i4.f1 = 0) ss2 on true
+ right join (select false as z) ss3 on true,
+ lateral (select i8.q2 as q2l where x limit 1) ss4
+where i8.q2 = 123;
+
-- Test proper handling of appendrel PHVs during useless-RTE removal
explain (costs off)
select * from
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-04 20:46:37 +0000