diff --git a/src/backend/distributed/planner/distributed_planner.c b/src/backend/distributed/planner/distributed_planner.c
index c25783565..7be023835 100644
--- a/src/backend/distributed/planner/distributed_planner.c
+++ b/src/backend/distributed/planner/distributed_planner.c
@@ -134,6 +134,7 @@ static PlannedStmt * PlanDistributedStmt(DistributedPlanningContext *planContext
 static RTEListProperties * GetRTEListProperties(List *rangeTableList);
 static List * TranslatedVars(PlannerInfo *root, int relationIndex);
 static void WarnIfListHasForeignDistributedTable(List *rangeTableList);
+static void ErrorIfMergeHasUnsupportedTables(Query *parse, List *rangeTableList);
 static List * GenerateImplicitJoinRestrictInfoList(PlannerInfo *plannerInfo,
 												   RelOptInfo *innerrel,
 												   RelOptInfo *outerrel);
diff --git a/src/test/regress/expected/coordinator_shouldhaveshards_0.out b/src/test/regress/expected/coordinator_shouldhaveshards_0.out
index 49a7578b2..425b5fffc 100644
--- a/src/test/regress/expected/coordinator_shouldhaveshards_0.out
+++ b/src/test/regress/expected/coordinator_shouldhaveshards_0.out
@@ -286,8 +286,8 @@ NOTICE:  executing the command locally: SELECT bytes FROM fetch_intermediate_res
 NOTICE:  executing the command locally: SELECT bytes FROM fetch_intermediate_results(ARRAY['repartition_26_2_3']::text[],'localhost',57637) bytes
 NOTICE:  executing the command locally: SELECT bytes FROM fetch_intermediate_results(ARRAY['repartition_26_3_3']::text[],'localhost',57638) bytes
 NOTICE:  executing the command locally: SELECT bytes FROM fetch_intermediate_results(ARRAY['repartition_26_4_3']::text[],'localhost',57636) bytes
-NOTICE:  executing the command locally: SELECT count(*) AS count FROM (read_intermediate_results('{repartition_25_1_0,repartition_25_2_0,repartition_25_3_0,repartition_25_4_0}'::text[], 'binary'::citus_copy_format) intermediate_result(column1 integer) JOIN read_intermediate_results('{repartition_26_1_0,repartition_26_2_0,repartition_26_3_0,repartition_26_4_0}'::text[], 'binary'::citus_copy_format) intermediate_result_1(column1 integer) ON ((intermediate_result.column1 OPERATOR(pg_catalog.=) intermediate_result_1.column1))) WHERE WHERE (intermediate_result_1.column1 OPERATOR(pg_catalog.=) intermediate_result.column1)
-NOTICE:  executing the command locally: SELECT count(*) AS count FROM (read_intermediate_results('{repartition_25_1_3,repartition_25_2_3,repartition_25_3_3,repartition_25_4_3}'::text[], 'binary'::citus_copy_format) intermediate_result(column1 integer) JOIN read_intermediate_results('{repartition_26_1_3,repartition_26_2_3,repartition_26_3_3,repartition_26_4_3}'::text[], 'binary'::citus_copy_format) intermediate_result_1(column1 integer) ON ((intermediate_result.column1 OPERATOR(pg_catalog.=) intermediate_result_1.column1))) WHERE WHERE (intermediate_result_1.column1 OPERATOR(pg_catalog.=) intermediate_result.column1)
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM (read_intermediate_results('{repartition_25_1_0,repartition_25_2_0,repartition_25_3_0,repartition_25_4_0}'::text[], 'binary'::citus_copy_format) intermediate_result(column1 integer) JOIN read_intermediate_results('{repartition_26_1_0,repartition_26_2_0,repartition_26_3_0,repartition_26_4_0}'::text[], 'binary'::citus_copy_format) intermediate_result_1(column1 integer) ON ((intermediate_result.column1 OPERATOR(pg_catalog.=) intermediate_result_1.column1))) WHERE (intermediate_result_1.column1 OPERATOR(pg_catalog.=) intermediate_result.column1)
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM (read_intermediate_results('{repartition_25_1_3,repartition_25_2_3,repartition_25_3_3,repartition_25_4_3}'::text[], 'binary'::citus_copy_format) intermediate_result(column1 integer) JOIN read_intermediate_results('{repartition_26_1_3,repartition_26_2_3,repartition_26_3_3,repartition_26_4_3}'::text[], 'binary'::citus_copy_format) intermediate_result_1(column1 integer) ON ((intermediate_result.column1 OPERATOR(pg_catalog.=) intermediate_result_1.column1))) WHERE (intermediate_result_1.column1 OPERATOR(pg_catalog.=) intermediate_result.column1)
  count
 ---------------------------------------------------------------------
    100
diff --git a/src/test/regress/expected/local_shard_execution_0.out b/src/test/regress/expected/local_shard_execution_0.out
index 4f5c0a3ba..d61e11846 100644
--- a/src/test/regress/expected/local_shard_execution_0.out
+++ b/src/test/regress/expected/local_shard_execution_0.out
@@ -473,8 +473,8 @@ NOTICE:  executing the command locally: SELECT first.b, first.c, first.d, second
 END;
 BEGIN;
 SELECT * FROM abcd first join abcd second USING(b) join abcd third on first.b=third.b ORDER BY 1,2,3,4;
-NOTICE:  executing the command locally: SELECT first.b, first.c, first.d, second.c, second.d, third.b, third.c, third.d FROM ((local_shard_execution.abcd_1470025 first JOIN local_shard_execution.abcd_1470025 second ON ((first.b OPERATOR(pg_catalog.=) second.b))) JOIN local_shard_execution.abcd_1470025 third ON ((first.b OPERATOR(pg_catalog.=) third.b))) WHERE true
-NOTICE:  executing the command locally: SELECT first.b, first.c, first.d, second.c, second.d, third.b, third.c, third.d FROM ((local_shard_execution.abcd_1470027 first JOIN local_shard_execution.abcd_1470027 second ON ((first.b OPERATOR(pg_catalog.=) second.b))) JOIN local_shard_execution.abcd_1470027 third ON ((first.b OPERATOR(pg_catalog.=) third.b))) WHERE true
+NOTICE:  executing the command locally: SELECT first.b, first.c, first.d, second.c, second.d, third.b, third.c, third.d FROM ((local_shard_execution.abcd_1470025 first JOIN local_shard_execution.abcd_1470025 second ON ((first.b OPERATOR(pg_catalog.=) second.b))) JOIN local_shard_execution.abcd_1470025 third ON ((first.b OPERATOR(pg_catalog.=) third.b))) WHERE ((second.b OPERATOR(pg_catalog.=) third.b) AND (second.b OPERATOR(pg_catalog.=) first.b))
+NOTICE:  executing the command locally: SELECT first.b, first.c, first.d, second.c, second.d, third.b, third.c, third.d FROM ((local_shard_execution.abcd_1470027 first JOIN local_shard_execution.abcd_1470027 second ON ((first.b OPERATOR(pg_catalog.=) second.b))) JOIN local_shard_execution.abcd_1470027 third ON ((first.b OPERATOR(pg_catalog.=) third.b))) WHERE ((second.b OPERATOR(pg_catalog.=) third.b) AND (second.b OPERATOR(pg_catalog.=) first.b))
  b | c | d | c | d | b | c | d
 ---------------------------------------------------------------------
  2 | 3 | 4 | 3 | 4 | 2 | 3 | 4