Test if regress test local_shard_execution_dropped_column is not

deterministically repeatable

src/test/regress/expected/local_shard_execution.out

@@ -3286,6 +3286,12 @@ SELECT pg_sleep(.1); -- wait to make sure the config has changed before running
 
 (1 row)
 
+SELECT 1;
+ ?column?
+---------------------------------------------------------------------
+        1
+(1 row)
+
 SET client_min_messages TO ERROR;
 SET search_path TO public;
 DROP SCHEMA local_shard_execution CASCADE;

src/test/regress/expected/local_shard_execution_dropped_column.out

@@ -193,6 +193,13 @@ execute p4(8);
 NOTICE:  executing the command locally: UPDATE local_shard_execution_dropped_column.t1_2460000 t1 SET a = (a OPERATOR(pg_catalog.+) 1) WHERE (c OPERATOR(pg_catalog.=) 8)
 execute p4(8);
 NOTICE:  executing the command locally: UPDATE local_shard_execution_dropped_column.t1_2460000 t1 SET a = (a OPERATOR(pg_catalog.+) 1) WHERE (c OPERATOR(pg_catalog.=) 8)
+-- arbitrary change to trigger test flakiness on this regress test
+SELECT 'random'::text;
+  text
+---------------------------------------------------------------------
+ random
+(1 row)
+
 \c - - - :master_port
 -- one another combination is that the shell table
 -- has a dropped column but not the shard, via rebalance operation
@@ -204,6 +211,12 @@ SELECT citus_move_shard_placement(2460000, 'localhost', :worker_1_port, 'localho
 
 (1 row)
 
+SELECT public.wait_for_resource_cleanup(); -- otherwise fails flakiness tests
+ wait_for_resource_cleanup
+---------------------------------------------------------------------
+
+(1 row)
+
 \c - - - :worker_2_port
 SET search_path TO local_shard_execution_dropped_column;
 -- show the dropped columns

src/test/regress/sql/local_shard_execution.sql

@@ -1441,6 +1441,8 @@ ALTER SYSTEM RESET citus.local_hostname;
 SELECT pg_reload_conf();
 SELECT pg_sleep(.1); -- wait to make sure the config has changed before running the GUC
 
+SELECT 1;
+
 SET client_min_messages TO ERROR;
 SET search_path TO public;
 DROP SCHEMA local_shard_execution CASCADE;

src/test/regress/sql/local_shard_execution_dropped_column.sql

@@ -78,6 +78,9 @@ execute p4(8);
 execute p4(8);
 execute p4(8);
 
+-- arbitrary change to trigger test flakiness on this regress test
+SELECT 'random'::text;
+
 \c - - - :master_port
 
 -- one another combination is that the shell table
@@ -86,6 +89,7 @@ SET search_path TO local_shard_execution_dropped_column;
 ALTER TABLE t1 DROP COLUMN a;
 
 SELECT citus_move_shard_placement(2460000, 'localhost', :worker_1_port, 'localhost', :worker_2_port, 'block_writes');
+SELECT public.wait_for_resource_cleanup(); -- otherwise fails flakiness tests
 
 \c - - - :worker_2_port
 SET search_path TO local_shard_execution_dropped_column;