Add a helper function to check explain has a single task

In order to avoid adding an alternative output, a function to check if a
given explan plan has a single task added. This doesn't change what the
changed tests intend to do.

src/test/regress/expected/drop_column_partitioned_table.out

@@ -226,78 +226,55 @@ EXPLAIN (COSTS FALSE) INSERT INTO sensors_2003 VALUES (3, '2003-01-01', row_to_j
                ->  Result
 (7 rows)
 
+SELECT public.explain_has_single_task(
+	$$
 EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors WHERE measureid = 3 AND eventdatetime = '2000-02-02';
-                                            QUERY PLAN
+	$$
+);
+ explain_has_single_task
 ---------------------------------------------------------------------
- Custom Scan (Citus Adaptive)
+ t
-   Task Count: 1
+(1 row)
-   Tasks Shown: All
-   ->  Task
-         Node: host=localhost port=xxxxx dbname=regression
-         ->  Aggregate
-               ->  Index Only Scan using sensors_2000_pkey_2580005 on sensors_2000_2580005 sensors
-                     Index Cond: ((measureid = 3) AND (eventdatetime = '2000-02-02'::date))
-(8 rows)
-
-EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2000 WHERE measureid = 3;
-                               QUERY PLAN
----------------------------------------------------------------------
- Custom Scan (Citus Adaptive)
-   Task Count: 1
-   Tasks Shown: All
-   ->  Task
-         Node: host=localhost port=xxxxx dbname=regression
-         ->  Aggregate
-               ->  Bitmap Heap Scan on sensors_2000_2580005 sensors_xxx
-                     Recheck Cond: (measureid = 3)
-                     ->  Bitmap Index Scan on sensors_2000_pkey_2580005
-                           Index Cond: (measureid = 3)
-(10 rows)
-
-EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2001 WHERE measureid = 3;
-                               QUERY PLAN
----------------------------------------------------------------------
- Custom Scan (Citus Adaptive)
-   Task Count: 1
-   Tasks Shown: All
-   ->  Task
-         Node: host=localhost port=xxxxx dbname=regression
-         ->  Aggregate
-               ->  Bitmap Heap Scan on sensors_2001_2580009 sensors_xxx
-                     Recheck Cond: (measureid = 3)
-                     ->  Bitmap Index Scan on sensors_2001_pkey_2580009
-                           Index Cond: (measureid = 3)
-(10 rows)
-
-EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2002 WHERE measureid = 3;
-                               QUERY PLAN
----------------------------------------------------------------------
- Custom Scan (Citus Adaptive)
-   Task Count: 1
-   Tasks Shown: All
-   ->  Task
-         Node: host=localhost port=xxxxx dbname=regression
-         ->  Aggregate
-               ->  Bitmap Heap Scan on sensors_2002_2580013 sensors_xxx
-                     Recheck Cond: (measureid = 3)
-                     ->  Bitmap Index Scan on sensors_2002_pkey_2580013
-                           Index Cond: (measureid = 3)
-(10 rows)
 
+SELECT public.explain_has_single_task(
+	$$
 EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2003 WHERE measureid = 3;
-                               QUERY PLAN
+	$$
+);
+ explain_has_single_task
 ---------------------------------------------------------------------
- Custom Scan (Citus Adaptive)
+ t
-   Task Count: 1
+(1 row)
-   Tasks Shown: All
+
-   ->  Task
+SELECT public.explain_has_single_task(
-         Node: host=localhost port=xxxxx dbname=regression
+	$$
-         ->  Aggregate
+EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2000 WHERE measureid = 3;
-               ->  Bitmap Heap Scan on sensors_2003_2580017 sensors_xxx
+	$$
-                     Recheck Cond: (measureid = 3)
+);
-                     ->  Bitmap Index Scan on sensors_2003_pkey_2580017
+ explain_has_single_task
-                           Index Cond: (measureid = 3)
+---------------------------------------------------------------------
-(10 rows)
+ t
+(1 row)
+
+SELECT public.explain_has_single_task(
+	$$
+EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2001 WHERE measureid = 3;
+	$$
+);
+ explain_has_single_task
+---------------------------------------------------------------------
+ t
+(1 row)
+
+SELECT public.explain_has_single_task(
+	$$
+EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2002 WHERE measureid = 3;
+	$$
+);
+ explain_has_single_task
+---------------------------------------------------------------------
+ t
+(1 row)
 
 -- execute 7 times to make sure it is re-cached
 EXECUTE drop_col_prepare_insert(3, '2000-10-01', row_to_json(row(1)));

src/test/regress/expected/multi_test_helpers.out

@@ -57,6 +57,20 @@ BEGIN
   END LOOP;
   RETURN false;
 END; $$ language plpgsql;
+--helper function to check there is a single task
+CREATE OR REPLACE FUNCTION explain_has_single_task(explain_command text)
+RETURNS BOOLEAN AS $$
+DECLARE
+  query_plan text;
+BEGIN
+  FOR query_plan IN EXECUTE explain_command LOOP
+    IF query_plan ILIKE '%Task Count: 1%'
+    THEN
+        RETURN true;
+    END IF;
+  END LOOP;
+  RETURN false;
+END; $$ language plpgsql;
 -- helper function to quickly run SQL on the whole cluster
 CREATE OR REPLACE FUNCTION run_command_on_coordinator_and_workers(p_sql text)
 RETURNS void LANGUAGE plpgsql AS $$

src/test/regress/sql/drop_column_partitioned_table.sql

@@ -111,11 +111,36 @@ EXPLAIN (COSTS FALSE) INSERT INTO sensors_2001 VALUES (3, '2001-01-01', row_to_j
 EXPLAIN (COSTS FALSE) INSERT INTO sensors_2002 VALUES (3, '2002-01-01', row_to_json(row(1)));
 EXPLAIN (COSTS FALSE) INSERT INTO sensors_2003 VALUES (3, '2003-01-01', row_to_json(row(1)));
 
+SELECT public.explain_has_single_task(
+	$$
 EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors WHERE measureid = 3 AND eventdatetime = '2000-02-02';
-EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2000 WHERE measureid = 3;
+	$$
-EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2001 WHERE measureid = 3;
+);
-EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2002 WHERE measureid = 3;
+
+SELECT public.explain_has_single_task(
+	$$
 EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2003 WHERE measureid = 3;
+	$$
+);
+
+SELECT public.explain_has_single_task(
+	$$
+EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2000 WHERE measureid = 3;
+	$$
+);
+
+SELECT public.explain_has_single_task(
+	$$
+EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2001 WHERE measureid = 3;
+	$$
+);
+
+SELECT public.explain_has_single_task(
+	$$
+EXPLAIN (COSTS FALSE) SELECT count(*) FROM sensors_2002 WHERE measureid = 3;
+	$$
+);
+
 
 -- execute 7 times to make sure it is re-cached
 EXECUTE drop_col_prepare_insert(3, '2000-10-01', row_to_json(row(1)));

src/test/regress/sql/multi_test_helpers.sql

@@ -63,6 +63,21 @@ BEGIN
   RETURN false;
 END; $$ language plpgsql;
 
+--helper function to check there is a single task
+CREATE OR REPLACE FUNCTION explain_has_single_task(explain_command text)
+RETURNS BOOLEAN AS $$
+DECLARE
+  query_plan text;
+BEGIN
+  FOR query_plan IN EXECUTE explain_command LOOP
+    IF query_plan ILIKE '%Task Count: 1%'
+    THEN
+        RETURN true;
+    END IF;
+  END LOOP;
+  RETURN false;
+END; $$ language plpgsql;
+
 -- helper function to quickly run SQL on the whole cluster
 CREATE OR REPLACE FUNCTION run_command_on_coordinator_and_workers(p_sql text)
 RETURNS void LANGUAGE plpgsql AS $$