Append nodes bearing non-relation RTIs are ordinary

this isn't really a correct fix

diff --git a/contrib/pg_plan_advice/pgpa_scan.c b/contrib/pg_plan_advice/pgpa_scan.c
index 61455c1874e909c2dd9b5b84f8c1d61cbcb96220..5d0c6f50438030372cfa6246e34195d814d2a9de 100644 (file)
--- a/contrib/pg_plan_advice/pgpa_scan.c
+++ b/contrib/pg_plan_advice/pgpa_scan.c
@@ -97,7 +97,38 @@ pgpa_build_scan(PlannedStmt *pstmt, Plan *plan, ElidedNode *elided_node,
                                break;
                        case T_Append:
                        case T_MergeAppend:
-                               strategy = PGPA_SCAN_PARTITIONWISE;
+                               {
+                                       int                     first_rti;
+                                       RangeTblEntry *first_rte;
+
+                                       first_rti = bms_next_member(relids, -1);
+                                       first_rte = rt_fetch(first_rti, pstmt->rtable);
+
+                                       /*
+                                        * Append and MergeAppend nodes can be the result either
+                                        * of set operations or of inheritance expansion. In the
+                                        * latter case, this plan node is telling us that the relid
+                                        * set found in the plan node was handled partitionwise,
+                                        * but in the former, it isn't. Even if the set operations
+                                        * planner has multiple ways to execute some set operation,
+                                        * we lack the ability to describe what it decided here,
+                                        * and hence just label this as an ordinary scan.
+                                        *
+                                        * XXX. This breaks with a single Append node that involves
+                                        * both set operations and inheritance expansion. Consider:
+                                        *
+                                        * create table foo (a int) partition by range (a);
+                                        * create table foo0 partition of foo for values
+                                        *      from (0) to (1000);
+                                        * create table foo1 partition of foo for values
+                                        *      from (1000) to (2000);
+                                        * explain select * from foo union all select 1;
+                                        */
+                                       if (first_rte->rtekind == RTE_RELATION)
+                                               strategy = PGPA_SCAN_PARTITIONWISE;
+                                       else
+                                               strategy = PGPA_SCAN_ORDINARY;
+                               }
                                break;
                        default:
                                strategy = PGPA_SCAN_ORDINARY;