Fix the unstable output of tests added by commit 8fccf758.

The test cases added by that commit were trying to test the exact number of
times a particular transaction has spilled. However, that number can vary if
any background transaction (say by autovacuum) happens in parallel to the main
transaction. So let's not try to verify the exact count.

Author: Amit Kapila
Reviewed-by: Sawada Masahiko
Discussion: https://postgr.es/m/CA+fd4k5_pPAYRTDrO2PbtTOe0eHQpBvuqmCr8ic39uTNmR49Eg@mail.gmail.com

contrib/test_decoding/expected/stats.out

@@ -42,23 +42,25 @@ $$ LANGUAGE plpgsql;
 BEGIN;
 INSERT INTO stats_test SELECT 'serialize-topbig--1:'||g.i FROM generate_series(1, 5000) g(i);
 COMMIT;
-SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL,NULL);
+SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL, NULL, 'skip-empty-xacts', '1');
  count 
 -------
-  5006
+  5002
 (1 row)
 
--- check stats, wait for stats collector to update.
+-- Check stats, wait for the stats collector to update. We can't test the
+-- exact stats count as that can vary if any background transaction (say by
+-- autovacuum) happens in parallel to the main transaction.
 SELECT wait_for_decode_stats(false);
  wait_for_decode_stats 
 -----------------------
  
 (1 row)
 
-SELECT name, spill_txns, spill_count FROM pg_stat_replication_slots;
+SELECT name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count FROM pg_stat_replication_slots;
       name       | spill_txns | spill_count 
 -----------------+------------+-------------
- regression_slot |          1 |          12
+ regression_slot | t          | t
 (1 row)
 
 -- reset the slot stats, and wait for stats collector to reset
@@ -81,10 +83,10 @@ SELECT name, spill_txns, spill_count FROM pg_stat_replication_slots;
 (1 row)
 
 -- decode and check stats again.
-SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL,NULL);
+SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL, NULL, 'skip-empty-xacts', '1');
  count 
 -------
-  5006
+  5002
 (1 row)
 
 SELECT wait_for_decode_stats(false);
@@ -93,10 +95,10 @@ SELECT wait_for_decode_stats(false);
  
 (1 row)
 
-SELECT name, spill_txns, spill_count FROM pg_stat_replication_slots;
+SELECT name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count FROM pg_stat_replication_slots;
       name       | spill_txns | spill_count 
 -----------------+------------+-------------
- regression_slot |          1 |          12
+ regression_slot | t          | t
 (1 row)
 
 DROP FUNCTION wait_for_decode_stats(bool);

contrib/test_decoding/sql/stats.sql

@@ -41,11 +41,13 @@ $$ LANGUAGE plpgsql;
 BEGIN;
 INSERT INTO stats_test SELECT 'serialize-topbig--1:'||g.i FROM generate_series(1, 5000) g(i);
 COMMIT;
-SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL,NULL);
+SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL, NULL, 'skip-empty-xacts', '1');
 
--- check stats, wait for stats collector to update.
+-- Check stats, wait for the stats collector to update. We can't test the
+-- exact stats count as that can vary if any background transaction (say by
+-- autovacuum) happens in parallel to the main transaction.
 SELECT wait_for_decode_stats(false);
-SELECT name, spill_txns, spill_count FROM pg_stat_replication_slots;
+SELECT name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count FROM pg_stat_replication_slots;
 
 -- reset the slot stats, and wait for stats collector to reset
 SELECT pg_stat_reset_replication_slot('regression_slot');
@@ -53,9 +55,9 @@ SELECT wait_for_decode_stats(true);
 SELECT name, spill_txns, spill_count FROM pg_stat_replication_slots;
 
 -- decode and check stats again.
-SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL,NULL);
+SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT wait_for_decode_stats(false);
-SELECT name, spill_txns, spill_count FROM pg_stat_replication_slots;
+SELECT name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count FROM pg_stat_replication_slots;
 
 DROP FUNCTION wait_for_decode_stats(bool);
 DROP TABLE stats_test;