diff options
Diffstat (limited to 'src/backend/optimizer/util/placeholder.c')
| -rw-r--r-- | src/backend/optimizer/util/placeholder.c | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/src/backend/optimizer/util/placeholder.c b/src/backend/optimizer/util/placeholder.c index 8a114fe9465..c7bfa293c9f 100644 --- a/src/backend/optimizer/util/placeholder.c +++ b/src/backend/optimizer/util/placeholder.c @@ -427,14 +427,16 @@ add_placeholders_to_base_rels(PlannerInfo *root) /* * add_placeholders_to_joinrel - * Add any required PlaceHolderVars to a join rel's targetlist; - * and if they contain lateral references, add those references to the - * joinrel's direct_lateral_relids. + * Add any newly-computable PlaceHolderVars to a join rel's targetlist; + * and if computable PHVs contain lateral references, add those + * references to the joinrel's direct_lateral_relids. * * A join rel should emit a PlaceHolderVar if (a) the PHV can be computed * at or below this join level and (b) the PHV is needed above this level. - * However, condition (a) is sufficient to add to direct_lateral_relids, - * as explained below. + * Our caller build_join_rel() has already added any PHVs that were computed + * in either join input rel, so we need add only newly-computable ones to + * the targetlist. However, direct_lateral_relids must be updated for every + * PHV computable at or below this join, as explained below. */ void add_placeholders_to_joinrel(PlannerInfo *root, RelOptInfo *joinrel, @@ -453,13 +455,10 @@ add_placeholders_to_joinrel(PlannerInfo *root, RelOptInfo *joinrel, /* Is it still needed above this joinrel? */ if (bms_nonempty_difference(phinfo->ph_needed, relids)) { - /* Yup, add it to the output */ - joinrel->reltarget->exprs = lappend(joinrel->reltarget->exprs, - phinfo->ph_var); - joinrel->reltarget->width += phinfo->ph_width; - /* - * Charge the cost of evaluating the contained expression if + * Yes, but only add to tlist if it wasn't computed in either + * input; otherwise it should be there already. Also, we + * charge the cost of evaluating the contained expression if * the PHV can be computed here but not in either input. This * is a bit bogus because we make the decision based on the * first pair of possible input relations considered for the @@ -472,12 +471,15 @@ add_placeholders_to_joinrel(PlannerInfo *root, RelOptInfo *joinrel, if (!bms_is_subset(phinfo->ph_eval_at, outer_rel->relids) && !bms_is_subset(phinfo->ph_eval_at, inner_rel->relids)) { + PlaceHolderVar *phv = phinfo->ph_var; QualCost cost; - cost_qual_eval_node(&cost, (Node *) phinfo->ph_var->phexpr, - root); + joinrel->reltarget->exprs = lappend(joinrel->reltarget->exprs, + phv); + cost_qual_eval_node(&cost, (Node *) phv->phexpr, root); joinrel->reltarget->cost.startup += cost.startup; joinrel->reltarget->cost.per_tuple += cost.per_tuple; + joinrel->reltarget->width += phinfo->ph_width; } } |