diff options
Diffstat (limited to 'src/backend/optimizer/plan/initsplan.c')
| -rw-r--r-- | src/backend/optimizer/plan/initsplan.c | 62 |
1 files changed, 61 insertions, 1 deletions
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c index 3c7fa632b8e..4481db5c341 100644 --- a/src/backend/optimizer/plan/initsplan.c +++ b/src/backend/optimizer/plan/initsplan.c @@ -204,6 +204,64 @@ add_vars_to_targetlist(PlannerInfo *root, List *vars, } } +/* + * extract_lateral_references + * If the specified RTE is a LATERAL subquery, extract all its references + * to Vars of the current query level, and make sure those Vars will be + * available for evaluation of the RTE. + * + * XXX this is rather duplicative of processing that has to happen elsewhere. + * Maybe it'd be a good idea to do this type of extraction further upstream + * and save the results? + */ +static void +extract_lateral_references(PlannerInfo *root, int rtindex) +{ + RangeTblEntry *rte = root->simple_rte_array[rtindex]; + List *vars; + List *newvars; + Relids where_needed; + ListCell *lc; + + /* No cross-references are possible if it's not LATERAL */ + if (!rte->lateral) + return; + + /* Fetch the appropriate variables */ + if (rte->rtekind == RTE_SUBQUERY) + vars = pull_vars_of_level((Node *) rte->subquery, 1); + else if (rte->rtekind == RTE_FUNCTION) + vars = pull_vars_of_level(rte->funcexpr, 0); + else + return; + + /* Copy each Var and adjust it to match our level */ + newvars = NIL; + foreach(lc, vars) + { + Var *var = (Var *) lfirst(lc); + + var = copyObject(var); + var->varlevelsup = 0; + newvars = lappend(newvars, var); + } + + /* + * We mark the Vars as being "needed" at the LATERAL RTE. This is a bit + * of a cheat: a more formal approach would be to mark each one as needed + * at the join of the LATERAL RTE with its source RTE. But it will work, + * and it's much less tedious than computing a separate where_needed for + * each Var. + */ + where_needed = bms_make_singleton(rtindex); + + /* Push the Vars into their source relations' targetlists */ + add_vars_to_targetlist(root, newvars, where_needed, false); + + list_free(newvars); + list_free(vars); +} + /***************************************************************************** * @@ -286,7 +344,9 @@ deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join, { int varno = ((RangeTblRef *) jtnode)->rtindex; - /* No quals to deal with, just return correct result */ + /* No quals to deal with, but do check for LATERAL subqueries */ + extract_lateral_references(root, varno); + /* Result qualscope is just the one Relid */ *qualscope = bms_make_singleton(varno); /* A single baserel does not create an inner join */ *inner_join_rels = NULL; |