MERGE minor errata

src/backend/executor/README

@@ -42,8 +42,8 @@ consists of a super-row that contains all the columns needed by any of the
 individual actions, plus CTID and TABLEOID junk columns. The CTID column is
 required to know if a matching target row was found or not and the TABLEOID
 column is needed to find the underlying target partition, in case when the
-target table is a partition table. When a matching target tuple is found, the
-CTID column identifies the matching target tuple and we attempt to activate
+target table is a partitioned table. When a matching target tuple is found,
+the CTID column identifies the matching tuple and we attempt to activate
 WHEN MATCHED actions. If a matching tuple is not found, then CTID column is
 NULL and we attempt to activate WHEN NOT MATCHED actions. Once we know which
 action is activated we form the final result row and apply only those changes.

src/backend/executor/execMerge.c

@@ -51,7 +51,7 @@ ExecMerge(ModifyTableState *mtstate, EState *estate, TupleTableSlot *slot,
 	Datum		datum;
 	bool		isNull;
 
-	Assert(resultRelInfo->ri_RelationDesc->rd_rel->relkind ||
+	Assert(resultRelInfo->ri_RelationDesc->rd_rel->relkind == RELKIND_RELATION ||
 		   resultRelInfo->ri_RelationDesc->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
 
 	/*

src/backend/executor/execPartition.c

@@ -314,9 +314,7 @@ ExecFindPartition(ResultRelInfo *resultRelInfo, PartitionDispatch *pd,
  * Given OID of the partition leaf, return the index of the leaf in the
  * partition hierarchy.
  *
- * NB: This is an O(N) operation. Unfortunately, there are many other problem
- * areas with more than a handful partitions, so we don't try to optimise this
- * code right now.
+ * XXX This is an O(N) operation and further optimization would be beneficial
  */
 int
 ExecFindPartitionByOid(PartitionTupleRouting *proute, Oid partoid)