diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
new file mode 100644
index c74bac2..b6452e9
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -1604,7 +1604,6 @@ rewriteValuesRTEToNulls(Query *parsetree
 	List	   *newValues;
 	ListCell   *lc;
 
-	Assert(rte->rtekind == RTE_VALUES);
 	newValues = NIL;
 	foreach(lc, rte->values_lists)
 	{
@@ -3861,12 +3860,39 @@ RewriteQuery(Query *parsetree, List *rew
 			/*
 			 * Each product query has its own copy of the VALUES RTE at the
 			 * same index in the rangetable, so we must finalize each one.
+			 *
+			 * Note that if the product query is an INSERT ... SELECT, then
+			 * the VALUES RTE will be at the same index in the SELECT part of
+			 * the product query rather than the top-level product query
+			 * itself.
 			 */
 			foreach(n, product_queries)
 			{
 				Query	   *pt = (Query *) lfirst(n);
-				RangeTblEntry *values_rte = rt_fetch(values_rte_index,
-													 pt->rtable);
+				RangeTblEntry *values_rte;
+
+				if (pt->commandType == CMD_INSERT &&
+					pt->jointree && IsA(pt->jointree, FromExpr) &&
+					list_length(pt->jointree->fromlist) == 1)
+				{
+					Node	   *jtnode = (Node *) linitial(pt->jointree->fromlist);
+
+					if (IsA(jtnode, RangeTblRef))
+					{
+						int			rtindex = ((RangeTblRef *) jtnode)->rtindex;
+						RangeTblEntry *src_rte = rt_fetch(rtindex, pt->rtable);
+
+						if (src_rte->rtekind == RTE_SUBQUERY &&
+							src_rte->subquery &&
+							IsA(src_rte->subquery, Query) &&
+							src_rte->subquery->commandType == CMD_SELECT)
+							pt = src_rte->subquery;
+					}
+				}
+
+				values_rte = rt_fetch(values_rte_index, pt->rtable);
+				if (values_rte->rtekind != RTE_VALUES)
+					elog(ERROR, "failed to find VALUES RTE in product query");
 
 				rewriteValuesRTEToNulls(pt, values_rte);
 			}
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
new file mode 100644
index 6f51c7e..58d962a
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -1008,16 +1008,20 @@ getInsertSelectQuery(Query *parsetree, Q
 		strcmp(rt_fetch(PRS2_NEW_VARNO, parsetree->rtable)->eref->aliasname,
 			   "new") == 0)
 		return parsetree;
-	Assert(parsetree->jointree && IsA(parsetree->jointree, FromExpr));
-	if (list_length(parsetree->jointree->fromlist) != 1)
+	if (!(parsetree->jointree &&
+		  IsA(parsetree->jointree, FromExpr) &&
+		  list_length(parsetree->jointree->fromlist) == 1))
 		elog(ERROR, "expected to find SELECT subquery");
 	rtr = (RangeTblRef *) linitial(parsetree->jointree->fromlist);
-	Assert(IsA(rtr, RangeTblRef));
+	if (!IsA(rtr, RangeTblRef))
+		elog(ERROR, "expected to find SELECT subquery");
 	selectrte = rt_fetch(rtr->rtindex, parsetree->rtable);
-	selectquery = selectrte->subquery;
-	if (!(selectquery && IsA(selectquery, Query) &&
-		  selectquery->commandType == CMD_SELECT))
+	if (!(selectrte->rtekind == RTE_SUBQUERY &&
+		  selectrte->subquery &&
+		  IsA(selectrte->subquery, Query) &&
+		  selectrte->subquery->commandType == CMD_SELECT))
 		elog(ERROR, "expected to find SELECT subquery");
+	selectquery = selectrte->subquery;
 	if (list_length(selectquery->rtable) >= 2 &&
 		strcmp(rt_fetch(PRS2_OLD_VARNO, selectquery->rtable)->eref->aliasname,
 			   "old") == 0 &&
diff --git a/src/test/regress/expected/updatable_views.out b/src/test/regress/expected/updatable_views.out
new file mode 100644
index 2b578cc..3bc38b6
--- a/src/test/regress/expected/updatable_views.out
+++ b/src/test/regress/expected/updatable_views.out
@@ -3296,6 +3296,25 @@ select * from base_tab_def order by a, c
     | View default  |               | View default | 
 (22 rows)
 
+-- Test a DO ALSO INSERT ... SELECT rule
+drop rule base_tab_def_view_ins_rule on base_tab_def_view;
+create rule base_tab_def_view_ins_rule as on insert to base_tab_def_view
+  do also insert into base_tab_def (a, b, e) select new.a, new.b, 'xxx';
+truncate base_tab_def;
+insert into base_tab_def_view values (1, default, default, default, default);
+insert into base_tab_def_view values (2, default, default, default, default),
+                                     (3, default, default, default, default);
+select * from base_tab_def order by a, e NULLS FIRST;
+ a |      b       |       c       |      d       |  e  
+---+--------------+---------------+--------------+-----
+ 1 | View default | Table default | View default | 
+ 1 | View default | Table default |              | xxx
+ 2 | View default | Table default | View default | 
+ 2 | View default | Table default |              | xxx
+ 3 | View default | Table default | View default | 
+ 3 | View default | Table default |              | xxx
+(6 rows)
+
 drop view base_tab_def_view;
 drop table base_tab_def;
 -- Test defaults with array assignments
diff --git a/src/test/regress/sql/updatable_views.sql b/src/test/regress/sql/updatable_views.sql
new file mode 100644
index a6aebbc..00810ce
--- a/src/test/regress/sql/updatable_views.sql
+++ b/src/test/regress/sql/updatable_views.sql
@@ -1717,6 +1717,16 @@ insert into base_tab_def_view values (15
 insert into base_tab_def_view values (17), (default);
 select * from base_tab_def order by a, c NULLS LAST;
 
+-- Test a DO ALSO INSERT ... SELECT rule
+drop rule base_tab_def_view_ins_rule on base_tab_def_view;
+create rule base_tab_def_view_ins_rule as on insert to base_tab_def_view
+  do also insert into base_tab_def (a, b, e) select new.a, new.b, 'xxx';
+truncate base_tab_def;
+insert into base_tab_def_view values (1, default, default, default, default);
+insert into base_tab_def_view values (2, default, default, default, default),
+                                     (3, default, default, default, default);
+select * from base_tab_def order by a, e NULLS FIRST;
+
 drop view base_tab_def_view;
 drop table base_tab_def;