diff options
Diffstat (limited to 'src/backend/optimizer/prep/prepjointree.c')
| -rw-r--r-- | src/backend/optimizer/prep/prepjointree.c | 44 |
1 files changed, 34 insertions, 10 deletions
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c index afeb6ddb8c4..875baefbd39 100644 --- a/src/backend/optimizer/prep/prepjointree.c +++ b/src/backend/optimizer/prep/prepjointree.c @@ -41,6 +41,8 @@ typedef struct pullup_replace_vars_context PlannerInfo *root; List *targetlist; /* tlist of subquery being pulled up */ RangeTblEntry *target_rte; /* RTE of subquery */ + Relids relids; /* relids within subquery, as numbered after + * pullup (set only if target_rte->lateral) */ bool *outer_hasSubLinks; /* -> outer query's hasSubLinks */ int varno; /* varno of subquery */ bool need_phvs; /* do we need PlaceHolderVars? */ @@ -884,14 +886,19 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte, /* * The subquery's targetlist items are now in the appropriate form to * insert into the top query, but if we are under an outer join then - * non-nullable items may have to be turned into PlaceHolderVars. If we - * are dealing with an appendrel member then anything that's not a simple - * Var has to be turned into a PlaceHolderVar. Set up appropriate context - * data for pullup_replace_vars. + * non-nullable items and lateral references may have to be turned into + * PlaceHolderVars. If we are dealing with an appendrel member then + * anything that's not a simple Var has to be turned into a + * PlaceHolderVar. Set up required context data for pullup_replace_vars. */ rvcontext.root = root; rvcontext.targetlist = subquery->targetList; rvcontext.target_rte = rte; + if (rte->lateral) + rvcontext.relids = get_relids_in_jointree((Node *) subquery->jointree, + true); + else /* won't need relids */ + rvcontext.relids = NULL; rvcontext.outer_hasSubLinks = &parse->hasSubLinks; rvcontext.varno = varno; rvcontext.need_phvs = (lowest_nulling_outer_join != NULL || @@ -1675,8 +1682,18 @@ pullup_replace_vars_callback(Var *var, if (newnode && IsA(newnode, Var) && ((Var *) newnode)->varlevelsup == 0) { - /* Simple Vars always escape being wrapped */ - wrap = false; + /* + * Simple Vars always escape being wrapped, unless they are + * lateral references to something outside the subquery being + * pulled up. (Even then, we could omit the PlaceHolderVar if + * the referenced rel is under the same lowest outer join, but + * it doesn't seem worth the trouble to check that.) + */ + if (rcon->target_rte->lateral && + !bms_is_member(((Var *) newnode)->varno, rcon->relids)) + wrap = true; + else + wrap = false; } else if (newnode && IsA(newnode, PlaceHolderVar) && ((PlaceHolderVar *) newnode)->phlevelsup == 0) @@ -1692,9 +1709,10 @@ pullup_replace_vars_callback(Var *var, else { /* - * If it contains a Var of current level, and does not contain - * any non-strict constructs, then it's certainly nullable so - * we don't need to insert a PlaceHolderVar. + * If it contains a Var of the subquery being pulled up, and + * does not contain any non-strict constructs, then it's + * certainly nullable so we don't need to insert a + * PlaceHolderVar. * * This analysis could be tighter: in particular, a non-strict * construct hidden within a lower-level PlaceHolderVar is not @@ -1703,8 +1721,14 @@ pullup_replace_vars_callback(Var *var, * * Note: in future maybe we should insert a PlaceHolderVar * anyway, if the tlist item is expensive to evaluate? + * + * For a LATERAL subquery, we have to check the actual var + * membership of the node, but if it's non-lateral then any + * level-zero var must belong to the subquery. */ - if (contain_vars_of_level((Node *) newnode, 0) && + if ((rcon->target_rte->lateral ? + bms_overlap(pull_varnos((Node *) newnode), rcon->relids) : + contain_vars_of_level((Node *) newnode, 0)) && !contain_nonstrict_functions((Node *) newnode)) { /* No wrap needed */ |