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Get rid of the planner's LateralJoinInfo data structure.

I originally modeled this data structure on SpecialJoinInfo, but after
commit acfcd45cac 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.
This commit is contained in:
Tom Lane
2015-12-11 15:52:16 -05:00
parent ed8bec915e
commit 4fcf48450d
17 changed files with 100 additions and 289 deletions

View File

@ -111,6 +111,7 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind)
rel->cheapest_total_path = NULL;
rel->cheapest_unique_path = NULL;
rel->cheapest_parameterized_paths = NIL;
rel->direct_lateral_relids = NULL;
rel->lateral_relids = NULL;
rel->relid = relid;
rel->rtekind = rte->rtekind;
@ -373,6 +374,10 @@ build_join_rel(PlannerInfo *root,
joinrel->cheapest_total_path = NULL;
joinrel->cheapest_unique_path = NULL;
joinrel->cheapest_parameterized_paths = NIL;
/* init direct_lateral_relids from children; we'll finish it up below */
joinrel->direct_lateral_relids =
bms_union(outer_rel->direct_lateral_relids,
inner_rel->direct_lateral_relids);
joinrel->lateral_relids = min_join_parameterization(root, joinrel->relids,
outer_rel, inner_rel);
joinrel->relid = 0; /* indicates not a baserel */
@ -422,6 +427,18 @@ build_join_rel(PlannerInfo *root,
build_joinrel_tlist(root, joinrel, inner_rel);
add_placeholders_to_joinrel(root, joinrel);
/*
* add_placeholders_to_joinrel also took care of adding the ph_lateral
* sets of any PlaceHolderVars computed here to direct_lateral_relids, so
* now we can finish computing that. This is much like the computation of
* the transitively-closed lateral_relids in min_join_parameterization,
* except that here we *do* have to consider the added PHVs.
*/
joinrel->direct_lateral_relids =
bms_del_members(joinrel->direct_lateral_relids, joinrel->relids);
if (bms_is_empty(joinrel->direct_lateral_relids))
joinrel->direct_lateral_relids = NULL;
/*
* Construct restrict and join clause lists for the new joinrel. (The
* caller might or might not need the restrictlist, but I need it anyway