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Get rid of the planner's LateralJoinInfo data structure.
I originally modeled this data structure on SpecialJoinInfo, but after commit acfcd45 that looks like a pretty poor decision. All we really need is relid sets identifying laterally-referenced rels; and most of the time, what we want to know about includes indirect lateral references, a case the LateralJoinInfo data was unsuited to compute with any efficiency. The previous commit redefined RelOptInfo.lateral_relids as the transitive closure of lateral references, so that it easily supports checking indirect references. For the places where we really do want just direct references, add a new RelOptInfo field direct_lateral_relids, which is easily set up as a copy of lateral_relids before we perform the transitive closure calculation. Then we can just drop lateral_info_list and LateralJoinInfo and the supporting code. This makes the planner's handling of lateral references noticeably more efficient, and shorter too. Such a change can't be back-patched into stable branches for fear of breaking extensions that might be looking at the planner's data structures; but it seems not too late to push it into 9.5, so I've done so.
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17 files changed

+100
-289
lines changed

17 files changed

+100
-289
lines changed

‎src/backend/nodes/copyfuncs.c

Lines changed: 0 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -2066,20 +2066,6 @@ _copySpecialJoinInfo(const SpecialJoinInfo *from)
20662066
return newnode;
20672067
}
20682068

2069-
/*
2070-
* _copyLateralJoinInfo
2071-
*/
2072-
static LateralJoinInfo *
2073-
_copyLateralJoinInfo(const LateralJoinInfo *from)
2074-
{
2075-
LateralJoinInfo *newnode = makeNode(LateralJoinInfo);
2076-
2077-
COPY_BITMAPSET_FIELD(lateral_lhs);
2078-
COPY_BITMAPSET_FIELD(lateral_rhs);
2079-
2080-
return newnode;
2081-
}
2082-
20832069
/*
20842070
* _copyAppendRelInfo
20852071
*/
@@ -4519,9 +4505,6 @@ copyObject(const void *from)
45194505
case T_SpecialJoinInfo:
45204506
retval = _copySpecialJoinInfo(from);
45214507
break;
4522-
case T_LateralJoinInfo:
4523-
retval = _copyLateralJoinInfo(from);
4524-
break;
45254508
case T_AppendRelInfo:
45264509
retval = _copyAppendRelInfo(from);
45274510
break;

‎src/backend/nodes/equalfuncs.c

Lines changed: 0 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -845,15 +845,6 @@ _equalSpecialJoinInfo(const SpecialJoinInfo *a, const SpecialJoinInfo *b)
845845
return true;
846846
}
847847

848-
static bool
849-
_equalLateralJoinInfo(const LateralJoinInfo *a, const LateralJoinInfo *b)
850-
{
851-
COMPARE_BITMAPSET_FIELD(lateral_lhs);
852-
COMPARE_BITMAPSET_FIELD(lateral_rhs);
853-
854-
return true;
855-
}
856-
857848
static bool
858849
_equalAppendRelInfo(const AppendRelInfo *a, const AppendRelInfo *b)
859850
{
@@ -2860,9 +2851,6 @@ equal(const void *a, const void *b)
28602851
case T_SpecialJoinInfo:
28612852
retval = _equalSpecialJoinInfo(a, b);
28622853
break;
2863-
case T_LateralJoinInfo:
2864-
retval = _equalLateralJoinInfo(a, b);
2865-
break;
28662854
case T_AppendRelInfo:
28672855
retval = _equalAppendRelInfo(a, b);
28682856
break;

‎src/backend/nodes/outfuncs.c

Lines changed: 1 addition & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -1847,7 +1847,6 @@ _outPlannerInfo(StringInfo str, const PlannerInfo *node)
18471847
WRITE_NODE_FIELD(right_join_clauses);
18481848
WRITE_NODE_FIELD(full_join_clauses);
18491849
WRITE_NODE_FIELD(join_info_list);
1850-
WRITE_NODE_FIELD(lateral_info_list);
18511850
WRITE_NODE_FIELD(append_rel_list);
18521851
WRITE_NODE_FIELD(rowMarks);
18531852
WRITE_NODE_FIELD(placeholder_list);
@@ -1892,6 +1891,7 @@ _outRelOptInfo(StringInfo str, const RelOptInfo *node)
18921891
WRITE_NODE_FIELD(cheapest_total_path);
18931892
WRITE_NODE_FIELD(cheapest_unique_path);
18941893
WRITE_NODE_FIELD(cheapest_parameterized_paths);
1894+
WRITE_BITMAPSET_FIELD(direct_lateral_relids);
18951895
WRITE_BITMAPSET_FIELD(lateral_relids);
18961896
WRITE_UINT_FIELD(relid);
18971897
WRITE_OID_FIELD(reltablespace);
@@ -2056,15 +2056,6 @@ _outSpecialJoinInfo(StringInfo str, const SpecialJoinInfo *node)
20562056
WRITE_NODE_FIELD(semi_rhs_exprs);
20572057
}
20582058

2059-
static void
2060-
_outLateralJoinInfo(StringInfo str, const LateralJoinInfo *node)
2061-
{
2062-
WRITE_NODE_TYPE("LATERALJOININFO");
2063-
2064-
WRITE_BITMAPSET_FIELD(lateral_lhs);
2065-
WRITE_BITMAPSET_FIELD(lateral_rhs);
2066-
}
2067-
20682059
static void
20692060
_outAppendRelInfo(StringInfo str, const AppendRelInfo *node)
20702061
{
@@ -3355,9 +3346,6 @@ _outNode(StringInfo str, const void *obj)
33553346
case T_SpecialJoinInfo:
33563347
_outSpecialJoinInfo(str, obj);
33573348
break;
3358-
case T_LateralJoinInfo:
3359-
_outLateralJoinInfo(str, obj);
3360-
break;
33613349
case T_AppendRelInfo:
33623350
_outAppendRelInfo(str, obj);
33633351
break;

‎src/backend/optimizer/path/joinrels.c

Lines changed: 6 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -231,7 +231,7 @@ join_search_one_level(PlannerInfo *root, int level)
231231
*/
232232
if (joinrels[level] == NIL &&
233233
root->join_info_list == NIL &&
234-
root->lateral_info_list == NIL)
234+
!root->hasLateralRTEs)
235235
elog(ERROR, "failed to build any %d-way joins", level);
236236
}
237237
}
@@ -559,15 +559,7 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
559559
match_sjinfo->jointype == JOIN_FULL))
560560
return false; /* not implementable as nestloop */
561561
/* check there is a direct reference from rel2 to rel1 */
562-
foreach(l, root->lateral_info_list)
563-
{
564-
LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(l);
565-
566-
if (bms_is_subset(ljinfo->lateral_rhs, rel2->relids) &&
567-
bms_is_subset(ljinfo->lateral_lhs, rel1->relids))
568-
break;
569-
}
570-
if (l == NULL)
562+
if (!bms_overlap(rel1->relids, rel2->direct_lateral_relids))
571563
return false; /* only indirect refs, so reject */
572564
/* check we won't have a dangerous PHV */
573565
if (have_dangerous_phv(root, rel1->relids, rel2->lateral_relids))
@@ -582,15 +574,7 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
582574
match_sjinfo->jointype == JOIN_FULL))
583575
return false; /* not implementable as nestloop */
584576
/* check there is a direct reference from rel1 to rel2 */
585-
foreach(l, root->lateral_info_list)
586-
{
587-
LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(l);
588-
589-
if (bms_is_subset(ljinfo->lateral_rhs, rel1->relids) &&
590-
bms_is_subset(ljinfo->lateral_lhs, rel2->relids))
591-
break;
592-
}
593-
if (l == NULL)
577+
if (!bms_overlap(rel2->relids, rel1->direct_lateral_relids))
594578
return false; /* only indirect refs, so reject */
595579
/* check we won't have a dangerous PHV */
596580
if (have_dangerous_phv(root, rel2->relids, rel1->lateral_relids))
@@ -922,17 +906,9 @@ have_join_order_restriction(PlannerInfo *root,
922906
* If either side has a direct lateral reference to the other, attempt the
923907
* join regardless of outer-join considerations.
924908
*/
925-
foreach(l, root->lateral_info_list)
926-
{
927-
LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(l);
928-
929-
if (bms_is_subset(ljinfo->lateral_rhs, rel2->relids) &&
930-
bms_overlap(ljinfo->lateral_lhs, rel1->relids))
931-
return true;
932-
if (bms_is_subset(ljinfo->lateral_rhs, rel1->relids) &&
933-
bms_overlap(ljinfo->lateral_lhs, rel2->relids))
934-
return true;
935-
}
909+
if (bms_overlap(rel1->relids, rel2->direct_lateral_relids) ||
910+
bms_overlap(rel2->relids, rel1->direct_lateral_relids))
911+
return true;
936912

937913
/*
938914
* Likewise, if both rels are needed to compute some PlaceHolderVar,

‎src/backend/optimizer/plan/analyzejoins.c

Lines changed: 0 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -439,9 +439,6 @@ remove_rel_from_query(PlannerInfo *root, int relid, Relids joinrelids)
439439
sjinfo->syn_righthand = bms_del_member(sjinfo->syn_righthand, relid);
440440
}
441441

442-
/* There shouldn't be any LATERAL info to translate, as yet */
443-
Assert(root->lateral_info_list == NIL);
444-
445442
/*
446443
* Likewise remove references from PlaceHolderVar data structures,
447444
* removing any no-longer-needed placeholders entirely.

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