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Further tighten nullingrel marking rules in build_joinrel_tlist(). 

The code I added in fee7b77b9 could misbehave if commute_above_r
contains multiple relids.  While adding too many relids here is
probably harmless (pre-fee7b77b9, we did it all the time), it's
not very expensive to be accurate: we just have to intersect
commute_above_r with the join's relids.

Discussion: https://postgr.es/m/17781-c0405c8b3cd5e072@postgresql.org
This commit is contained in:
Tom Lane 2023-02-08 14:45:36 -05:00
parent 798c017634
commit d1c9c864fc
1 changed files with 11 additions and 9 deletions
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20
src/backend/optimizer/util/relnode.c
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@ -1051,9 +1051,9 @@ min_join_parameterization(PlannerInfo *root,
* A leftjoin (B leftjoin C on (Pbc)) on (Pab)
* Here the now-upper A/B join must not mark C columns as nulled by itself.
*
* Second, if sjinfo->commute_above_r is already part of the joinrel then
* it is added to the nulling bitmaps of nullable Vars. This takes care of
* the reverse case where we implement
* Second, any relid in sjinfo->commute_above_r that is already part of
* the joinrel is added to the nulling bitmaps of nullable Vars and PHVs.
* This takes care of the reverse case where we implement
* A leftjoin (B leftjoin C on (Pbc)) on (Pab)
* as
* (A leftjoin B on (Pab)) leftjoin C on (Pbc)
@ -1100,9 +1100,10 @@ build_joinrel_tlist(PlannerInfo *root, RelOptInfo *joinrel,
bms_is_subset(phv->phrels, sjinfo->syn_lefthand))))
phv->phnullingrels = bms_add_member(phv->phnullingrels,
sjinfo->ojrelid);
if (bms_overlap(sjinfo->commute_above_r, joinrel->relids))
phv->phnullingrels = bms_add_members(phv->phnullingrels,
sjinfo->commute_above_r);
phv->phnullingrels =
bms_join(phv->phnullingrels,
bms_intersect(sjinfo->commute_above_r,
relids));
}
joinrel->reltarget->exprs = lappend(joinrel->reltarget->exprs,
@ -1164,9 +1165,10 @@ build_joinrel_tlist(PlannerInfo *root, RelOptInfo *joinrel,
bms_is_member(var->varno, sjinfo->syn_lefthand))))
var->varnullingrels = bms_add_member(var->varnullingrels,
sjinfo->ojrelid);
if (bms_overlap(sjinfo->commute_above_r, joinrel->relids))
var->varnullingrels = bms_add_members(var->varnullingrels,
sjinfo->commute_above_r);
var->varnullingrels =
bms_join(var->varnullingrels,
bms_intersect(sjinfo->commute_above_r,
relids));
}
joinrel->reltarget->exprs = lappend(joinrel->reltarget->exprs,