diff --git a/src/gausskernel/optimizer/plan/createplan.cpp b/src/gausskernel/optimizer/plan/createplan.cpp
index 6c7476aa6..890916aa9 100644
--- a/src/gausskernel/optimizer/plan/createplan.cpp
+++ b/src/gausskernel/optimizer/plan/createplan.cpp
@@ -1072,8 +1072,8 @@ static Plan* create_append_plan(PlannerInfo* root, AppendPath* best_path)
          * subquery's rangetable so that the executor will apply permissions
          * checks to those rels at runtime.)
          */
-        if (rel->rtekind == RTE_SUBQUERY) {
-            Assert(is_dummy_plan(rel->subplan));
+        if (rel->rtekind == RTE_SUBQUERY &&
+            (rel->subplan != NULL && is_dummy_plan(rel->subplan) == true)) {
             return (Plan*)make_subqueryscan(tlist, NIL, rel->relid, rel->subplan);
         } else {
             /* Generate a Result plan with constant-FALSE gating qual */
diff --git a/src/test/regress/expected/test_sqlsmith.out b/src/test/regress/expected/test_sqlsmith.out
new file mode 100644
index 000000000..3c8468602
--- /dev/null
+++ b/src/test/regress/expected/test_sqlsmith.out
@@ -0,0 +1,115 @@
+select  
+  pg_catalog.sysdate() as c0, 
+  pg_catalog.sysdate() as c1
+  from
+  pg_catalog.gs_wlm_ec_operator_info as sample_0
+  left join (select  
+  case when (select pg_catalog.max(start_date) from pg_catalog.pg_job)
+  = (select start_date from pg_catalog.pg_job limit 1 )
+  then ref_0.nodename else ref_0.nodename end
+  as c0
+  from
+  pg_catalog.gs_total_memory_detail as ref_0
+  where false
+  limit 121) as subq_0
+  on (pg_catalog.polygon(
+  cast(cast(null as circle) as circle)) |>> case when sample_0.average_peak_memory > cast(null as int8) then cast(null as polygon) else cast(null as polygon) end
+  )
+  where true;
+ c0 | c1 
+----+----
+(0 rows)
+
+
+select  pg_catalog.max(
+      cast(cast(null as "date") as "date")) over (partition by ref_0.catchup_start order by ref_0.peer_role) as c0, 
+      pg_catalog.inet_server_port() as c1, 
+      ref_0.peer_role as c2, 
+      ref_0.lwpid as c3, 
+      pg_catalog.timeofday() as c4, 
+      ref_0.catchup_end as c5, 
+     case when true then ref_0.catchup_end else ref_0.catchup_end end
+     as c6, 
+     ref_0.catchup_start as c7
+     from 
+     pg_catalog.pg_get_senders_catchup_time as ref_0
+     where cast(coalesce(pg_catalog.int4_bpchar(
+     cast(ref_0.lwpid as int4)),
+     pg_catalog.int1_bpchar(
+     cast((select pg_catalog.bit_and(attcmprmode) from pg_catalog.pg_attribute)
+     as int1))) as bpchar) < case when case when ref_0.catchup_end >= case when cast(null as circle) <> cast(null as circle) then cast(null as "date") else cast(null as "date") end
+     then case when EXISTS (
+     select  
+     ref_1.ftoptions as c0, 
+     ref_1.xc_node_id as c1, 
+     ref_0.type as c2, 
+     ref_0.catchup_end as c3, 
+     ref_0.pid as c4, 
+     ref_1.ftwriteonly as c5, 
+     ref_0.catchup_start as c6, 
+     ref_0.catchup_start as c7, 
+     ref_0.pid as c8, 
+     ref_1.xc_node_id as c9, 
+     ref_1.ftserver as c10, 
+     61 as c11
+     from 
+     pg_catalog.pg_foreign_table as ref_1
+     where cast(null as polygon) >> cast(null as polygon)) then cast(null as raw) else cast(null as raw) end
+     else case when EXISTS (
+     select  ref_1.ftoptions as c0, 
+             ref_1.xc_node_id as c1, 
+             ref_0.type as c2, 
+             ref_0.catchup_end as c3, 
+             ref_0.pid as c4, 
+             ref_1.ftwriteonly as c5, 
+             ref_0.catchup_start as c6, 
+             ref_0.catchup_start as c7, 
+             ref_0.pid as c8, 
+             ref_1.xc_node_id as c9, 
+             ref_1.ftserver as c10, 
+             61 as c11
+             from 
+             pg_catalog.pg_foreign_table as ref_1
+             where cast(null as polygon) >> cast(null as polygon)) then cast(null as raw) else cast(null as raw) end
+             end
+             = cast(null as raw) then cast(null as bpchar) else cast(null as bpchar) end
+             limit 77;
+ c0 | c1 | c2 | c3 | c4 | c5 | c6 | c7 
+----+----+----+----+----+----+----+----
+(0 rows)
+
+
+select  
+    sample_0.adnum as c0, 
+    (select starelid from pg_catalog.pg_statistic limit 1 offset 2) as c1, 
+    subq_0.c0 as c2, 
+    sample_0.adnum as c3, 
+    subq_0.c0 as c4, 
+    sample_0.adrelid as c5
+from 
+    pg_catalog.pg_attrdef as sample_0 tablesample system (7.1) 
+    left join 
+      (select  
+          (select schemaname from pg_catalog.pg_stat_xact_sys_tables limit 1 offset 3)  as c0, 
+          ref_0.catalog_name as c1
+       from 
+            information_schema.information_schema_catalog_name as ref_0
+       where 
+           (cast(null as circle) ~ cast(null as point)) 
+           or 
+           (
+            (select group_buckets from pg_catalog.pgxc_group limit 1 offset 3)
+             ~>~ 
+            (select pg_catalog.listagg(null_frac) from pg_catalog.pg_stats)
+            )
+      ) as subq_0
+on (case when true then cast(null as circle) 
+         else cast(null as circle) end
+    <> cast(coalesce(cast(null as circle),
+       cast(null as circle)) as circle))
+where 
+    pg_catalog.now() <= pg_catalog.pg_systimestamp()
+ c0 | c1 | c2 | c3 | c4 | c5 
+----+----+----+----+----+----
+(0 rows)
+
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index a5083e127..8989683f4 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -1,3 +1,5 @@
+# test random SQL statements generated by sqlsmith
+test: test_sqlsmith
 test: partiton_pathkey_col_plan partiton_pathkey_col_randomexec partiton_pathkey_row_plan partiton_pathkey_row_randomexec
 #test the locales setting expect not affacted each other
 test: pg_session_locale
diff --git a/src/test/regress/sql/test_sqlsmith.sql b/src/test/regress/sql/test_sqlsmith.sql
new file mode 100644
index 000000000..4346bf4c7
--- /dev/null
+++ b/src/test/regress/sql/test_sqlsmith.sql
@@ -0,0 +1,103 @@
+select  
+  pg_catalog.sysdate() as c0, 
+  pg_catalog.sysdate() as c1
+  from
+  pg_catalog.gs_wlm_ec_operator_info as sample_0
+  left join (select  
+  case when (select pg_catalog.max(start_date) from pg_catalog.pg_job)
+  = (select start_date from pg_catalog.pg_job limit 1 )
+  then ref_0.nodename else ref_0.nodename end
+  as c0
+  from
+  pg_catalog.gs_total_memory_detail as ref_0
+  where false
+  limit 121) as subq_0
+  on (pg_catalog.polygon(
+  cast(cast(null as circle) as circle)) |>> case when sample_0.average_peak_memory > cast(null as int8) then cast(null as polygon) else cast(null as polygon) end
+  )
+  where true;
+
+select  pg_catalog.max(
+      cast(cast(null as "date") as "date")) over (partition by ref_0.catchup_start order by ref_0.peer_role) as c0, 
+      pg_catalog.inet_server_port() as c1, 
+      ref_0.peer_role as c2, 
+      ref_0.lwpid as c3, 
+      pg_catalog.timeofday() as c4, 
+      ref_0.catchup_end as c5, 
+     case when true then ref_0.catchup_end else ref_0.catchup_end end
+     as c6, 
+     ref_0.catchup_start as c7
+     from 
+     pg_catalog.pg_get_senders_catchup_time as ref_0
+     where cast(coalesce(pg_catalog.int4_bpchar(
+     cast(ref_0.lwpid as int4)),
+     pg_catalog.int1_bpchar(
+     cast((select pg_catalog.bit_and(attcmprmode) from pg_catalog.pg_attribute)
+     as int1))) as bpchar) < case when case when ref_0.catchup_end >= case when cast(null as circle) <> cast(null as circle) then cast(null as "date") else cast(null as "date") end
+     then case when EXISTS (
+     select  
+     ref_1.ftoptions as c0, 
+     ref_1.xc_node_id as c1, 
+     ref_0.type as c2, 
+     ref_0.catchup_end as c3, 
+     ref_0.pid as c4, 
+     ref_1.ftwriteonly as c5, 
+     ref_0.catchup_start as c6, 
+     ref_0.catchup_start as c7, 
+     ref_0.pid as c8, 
+     ref_1.xc_node_id as c9, 
+     ref_1.ftserver as c10, 
+     61 as c11
+     from 
+     pg_catalog.pg_foreign_table as ref_1
+     where cast(null as polygon) >> cast(null as polygon)) then cast(null as raw) else cast(null as raw) end
+     else case when EXISTS (
+     select  ref_1.ftoptions as c0, 
+             ref_1.xc_node_id as c1, 
+             ref_0.type as c2, 
+             ref_0.catchup_end as c3, 
+             ref_0.pid as c4, 
+             ref_1.ftwriteonly as c5, 
+             ref_0.catchup_start as c6, 
+             ref_0.catchup_start as c7, 
+             ref_0.pid as c8, 
+             ref_1.xc_node_id as c9, 
+             ref_1.ftserver as c10, 
+             61 as c11
+             from 
+             pg_catalog.pg_foreign_table as ref_1
+             where cast(null as polygon) >> cast(null as polygon)) then cast(null as raw) else cast(null as raw) end
+             end
+             = cast(null as raw) then cast(null as bpchar) else cast(null as bpchar) end
+             limit 77;
+
+select  
+    sample_0.adnum as c0, 
+    (select starelid from pg_catalog.pg_statistic limit 1 offset 2) as c1, 
+    subq_0.c0 as c2, 
+    sample_0.adnum as c3, 
+    subq_0.c0 as c4, 
+    sample_0.adrelid as c5
+from 
+    pg_catalog.pg_attrdef as sample_0 tablesample system (7.1) 
+    left join 
+      (select  
+          (select schemaname from pg_catalog.pg_stat_xact_sys_tables limit 1 offset 3)  as c0, 
+          ref_0.catalog_name as c1
+       from 
+            information_schema.information_schema_catalog_name as ref_0
+       where 
+           (cast(null as circle) ~ cast(null as point)) 
+           or 
+           (
+            (select group_buckets from pg_catalog.pgxc_group limit 1 offset 3)
+             ~>~ 
+            (select pg_catalog.listagg(null_frac) from pg_catalog.pg_stats)
+            )
+      ) as subq_0
+on (case when true then cast(null as circle) 
+         else cast(null as circle) end
+    <> cast(coalesce(cast(null as circle),
+       cast(null as circle)) as circle))
+where 
+    pg_catalog.now() <= pg_catalog.pg_systimestamp()
\ No newline at end of file