add test that really execute parallel query

Author: rapimo

test/expected/parallel.out

@@ -62,3 +62,21 @@ EXPLAIN (COSTS OFF) SELECT * FROM kafka_test_part WHERE ((part = 1 or part = 2)
          scanning: PARTITION = 5 AND OFFSET = 12
 (10 rows)
 
+SELECT COUNT(*) FROM kafka_test_part ;
+ count  
+--------
+ 100000
+(1 row)
+
+EXPLAIN (COSTS OFF) SELECT COUNT(*) FROM kafka_test_part ;
+                          QUERY PLAN                          
+--------------------------------------------------------------
+ Finalize Aggregate
+   ->  Gather
+         Workers Planned: 3
+         ->  Partial Aggregate
+               ->  Parallel Foreign Scan on kafka_test_part
+                     Kafka topic: contrib_regress4
+                     scanning: PARTITION >= 0 AND OFFSET >= 0
+(7 rows)
+

test/sql/parallel.sql

@@ -22,3 +22,5 @@ EXPLAIN (COSTS OFF) SELECT * FROM kafka_test_part WHERE offs = 1 AND part = 0;
 EXPLAIN (COSTS OFF) SELECT * FROM kafka_test_part WHERE ((part = 1 or part = 2) and offs = 3) OR (part = 4 and offs=7);
 EXPLAIN (COSTS OFF) SELECT * FROM kafka_test_part WHERE ((part = 1 or part = 2) and offs = 3) OR ((part = 4 and offs=7 ) or ( part = 5 and (offs = 10 or offs=12)) );
 
+SELECT COUNT(*) FROM kafka_test_part ;
+EXPLAIN (COSTS OFF) SELECT COUNT(*) FROM kafka_test_part ;