* Handle a simple Var for examine_variable
*
* This is split out as a subroutine so that we can recurse to deal with
- * Vars referencing subqueries.
+ * Vars referencing subqueries (either sub-SELECT-in-FROM or CTE style).
*
* We already filled in all the fields of *vardata except for the stats tuple.
*/
vardata->acl_ok = true;
}
}
- else if (rte->rtekind == RTE_SUBQUERY && !rte->inh)
+ else if ((rte->rtekind == RTE_SUBQUERY && !rte->inh) ||
+ (rte->rtekind == RTE_CTE && !rte->self_reference))
{
/*
- * Plain subquery (not one that was converted to an appendrel).
+ * Plain subquery (not one that was converted to an appendrel) or
+ * non-recursive CTE. In either case, we can try to find out what the
+ * Var refers to within the subquery. We skip this for appendrel and
+ * recursive-CTE cases because any column stats we did find would
+ * likely not be very relevant.
*/
- Query *subquery = rte->subquery;
- RelOptInfo *rel;
+ PlannerInfo *subroot;
+ Query *subquery;
+ List *subtlist;
TargetEntry *ste;
/*
if (var->varattno == InvalidAttrNumber)
return;
+ /*
+ * Otherwise, find the subquery's planner subroot.
+ */
+ if (rte->rtekind == RTE_SUBQUERY)
+ {
+ RelOptInfo *rel;
+
+ /*
+ * Fetch RelOptInfo for subquery. Note that we don't change the
+ * rel returned in vardata, since caller expects it to be a rel of
+ * the caller's query level. Because we might already be
+ * recursing, we can't use that rel pointer either, but have to
+ * look up the Var's rel afresh.
+ */
+ rel = find_base_rel(root, var->varno);
+
+ subroot = rel->subroot;
+ }
+ else
+ {
+ /* CTE case is more difficult */
+ PlannerInfo *cteroot;
+ Index levelsup;
+ int ndx;
+ int plan_id;
+ ListCell *lc;
+
+ /*
+ * Find the referenced CTE, and locate the subroot previously made
+ * for it.
+ */
+ levelsup = rte->ctelevelsup;
+ cteroot = root;
+ while (levelsup-- > 0)
+ {
+ cteroot = cteroot->parent_root;
+ if (!cteroot) /* shouldn't happen */
+ elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
+ }
+
+ /*
+ * Note: cte_plan_ids can be shorter than cteList, if we are still
+ * working on planning the CTEs (ie, this is a side-reference from
+ * another CTE). So we mustn't use forboth here.
+ */
+ ndx = 0;
+ foreach(lc, cteroot->parse->cteList)
+ {
+ CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
+
+ if (strcmp(cte->ctename, rte->ctename) == 0)
+ break;
+ ndx++;
+ }
+ if (lc == NULL) /* shouldn't happen */
+ elog(ERROR, "could not find CTE \"%s\"", rte->ctename);
+ if (ndx >= list_length(cteroot->cte_plan_ids))
+ elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
+ plan_id = list_nth_int(cteroot->cte_plan_ids, ndx);
+ if (plan_id <= 0)
+ elog(ERROR, "no plan was made for CTE \"%s\"", rte->ctename);
+ subroot = list_nth(root->glob->subroots, plan_id - 1);
+ }
+
+ /* If the subquery hasn't been planned yet, we have to punt */
+ if (subroot == NULL)
+ return;
+ Assert(IsA(subroot, PlannerInfo));
+
+ /*
+ * We must use the subquery parsetree as mangled by the planner, not
+ * the raw version from the RTE, because we need a Var that will refer
+ * to the subroot's live RelOptInfos. For instance, if any subquery
+ * pullup happened during planning, Vars in the targetlist might have
+ * gotten replaced, and we need to see the replacement expressions.
+ */
+ subquery = subroot->parse;
+ Assert(IsA(subquery, Query));
+
/*
* Punt if subquery uses set operations or GROUP BY, as these will
* mash underlying columns' stats beyond recognition. (Set ops are
subquery->groupingSets)
return;
- /*
- * OK, fetch RelOptInfo for subquery. Note that we don't change the
- * rel returned in vardata, since caller expects it to be a rel of the
- * caller's query level. Because we might already be recursing, we
- * can't use that rel pointer either, but have to look up the Var's
- * rel afresh.
- */
- rel = find_base_rel(root, var->varno);
-
- /* If the subquery hasn't been planned yet, we have to punt */
- if (rel->subroot == NULL)
- return;
- Assert(IsA(rel->subroot, PlannerInfo));
-
- /*
- * Switch our attention to the subquery as mangled by the planner. It
- * was okay to look at the pre-planning version for the tests above,
- * but now we need a Var that will refer to the subroot's live
- * RelOptInfos. For instance, if any subquery pullup happened during
- * planning, Vars in the targetlist might have gotten replaced, and we
- * need to see the replacement expressions.
- */
- subquery = rel->subroot->parse;
- Assert(IsA(subquery, Query));
-
/* Get the subquery output expression referenced by the upper Var */
- ste = get_tle_by_resno(subquery->targetList, var->varattno);
+ if (subquery->returningList)
+ subtlist = subquery->returningList;
+ else
+ subtlist = subquery->targetList;
+ ste = get_tle_by_resno(subtlist, var->varattno);
if (ste == NULL || ste->resjunk)
elog(ERROR, "subquery %s does not have attribute %d",
rte->eref->aliasname, var->varattno);
* if the underlying column is unique, the subquery may have
* joined to other tables in a way that creates duplicates.
*/
- examine_simple_variable(rel->subroot, var, vardata);
+ examine_simple_variable(subroot, var, vardata);
}
}
else
{
/*
- * Otherwise, the Var comes from a FUNCTION, VALUES, or CTE RTE. (We
- * won't see RTE_JOIN here because join alias Vars have already been
+ * Otherwise, the Var comes from a FUNCTION or VALUES RTE. (We won't
+ * see RTE_JOIN here because join alias Vars have already been
* flattened.) There's not much we can do with function outputs, but
- * maybe someday try to be smarter about VALUES and/or CTEs.
+ * maybe someday try to be smarter about VALUES.
*/
}
}
projects / users / rhaas / postgres.git / commitdiff