diff options
Diffstat (limited to 'src/backend/optimizer/path/joinpath.c')
| -rw-r--r-- | src/backend/optimizer/path/joinpath.c | 73 |
1 files changed, 15 insertions, 58 deletions
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c index a35c881fd92..0f040331665 100644 --- a/src/backend/optimizer/path/joinpath.c +++ b/src/backend/optimizer/path/joinpath.c @@ -86,7 +86,6 @@ add_paths_to_joinrel(PlannerInfo *root, extra.mergeclause_list = NIL; extra.sjinfo = sjinfo; extra.param_source_rels = NULL; - extra.extra_lateral_rels = NULL; /* * Find potential mergejoin clauses. We can skip this if we are not @@ -151,60 +150,14 @@ add_paths_to_joinrel(PlannerInfo *root, } /* - * However, when a LATERAL subquery is involved, we have to be a bit - * laxer, because there will simply not be any paths for the joinrel that - * aren't parameterized by whatever the subquery is parameterized by, - * unless its parameterization is resolved within the joinrel. Hence, add - * to param_source_rels anything that is laterally referenced in either - * input and is not in the join already. + * However, when a LATERAL subquery is involved, there will simply not be + * any paths for the joinrel that aren't parameterized by whatever the + * subquery is parameterized by, unless its parameterization is resolved + * within the joinrel. So we might as well allow additional dependencies + * on whatever residual lateral dependencies the joinrel will have. */ - foreach(lc, root->lateral_info_list) - { - LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(lc); - - if (bms_is_subset(ljinfo->lateral_rhs, joinrel->relids)) - extra.param_source_rels = bms_join(extra.param_source_rels, - bms_difference(ljinfo->lateral_lhs, - joinrel->relids)); - } - - /* - * Another issue created by LATERAL references is that PlaceHolderVars - * that need to be computed at this join level might contain lateral - * references to rels not in the join, meaning that the paths for the join - * would need to be marked as parameterized by those rels, independently - * of all other considerations. Set extra_lateral_rels to the set of such - * rels. This will not affect our decisions as to which paths to - * generate; we merely add these rels to their required_outer sets. - */ - foreach(lc, root->placeholder_list) - { - PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc); - - /* PHVs without lateral refs can be skipped over quickly */ - if (phinfo->ph_lateral == NULL) - continue; - /* Is it due to be evaluated at this join, and not in either input? */ - if (bms_is_subset(phinfo->ph_eval_at, joinrel->relids) && - !bms_is_subset(phinfo->ph_eval_at, outerrel->relids) && - !bms_is_subset(phinfo->ph_eval_at, innerrel->relids)) - { - /* Yes, remember its lateral rels */ - extra.extra_lateral_rels = bms_add_members(extra.extra_lateral_rels, - phinfo->ph_lateral); - } - } - - /* - * Make sure extra_lateral_rels doesn't list anything within the join, and - * that it's NULL if empty. (This allows us to use bms_add_members to add - * it to required_outer below, while preserving the property that - * required_outer is exactly NULL if empty.) - */ - extra.extra_lateral_rels = bms_del_members(extra.extra_lateral_rels, - joinrel->relids); - if (bms_is_empty(extra.extra_lateral_rels)) - extra.extra_lateral_rels = NULL; + extra.param_source_rels = bms_add_members(extra.param_source_rels, + joinrel->lateral_relids); /* * 1. Consider mergejoin paths where both relations must be explicitly @@ -386,9 +339,13 @@ try_nestloop_path(PlannerInfo *root, /* * Independently of that, add parameterization needed for any - * PlaceHolderVars that need to be computed at the join. + * PlaceHolderVars that need to be computed at the join. We can handle + * that just by adding joinrel->lateral_relids; that might include some + * rels that are already in required_outer, but no harm done. (Note that + * lateral_relids is exactly NULL if empty, so this will not break the + * property that required_outer is too.) */ - required_outer = bms_add_members(required_outer, extra->extra_lateral_rels); + required_outer = bms_add_members(required_outer, joinrel->lateral_relids); /* * Do a precheck to quickly eliminate obviously-inferior paths. We @@ -465,7 +422,7 @@ try_mergejoin_path(PlannerInfo *root, * Independently of that, add parameterization needed for any * PlaceHolderVars that need to be computed at the join. */ - required_outer = bms_add_members(required_outer, extra->extra_lateral_rels); + required_outer = bms_add_members(required_outer, joinrel->lateral_relids); /* * If the given paths are already well enough ordered, we can skip doing @@ -547,7 +504,7 @@ try_hashjoin_path(PlannerInfo *root, * Independently of that, add parameterization needed for any * PlaceHolderVars that need to be computed at the join. */ - required_outer = bms_add_members(required_outer, extra->extra_lateral_rels); + required_outer = bms_add_members(required_outer, joinrel->lateral_relids); /* * See comments in try_nestloop_path(). Also note that hashjoin paths |