1 files changed, 143 insertions, 0 deletions
diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
new file mode 100644
index 0000000..206c0a1
--- /dev/null
+++ b/contrib/test_decoding/expected/stats.out
@@ -0,0 +1,143 @@
+-- predictability
+SET synchronous_commit = on;
+SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_stats', 'test_decoding');
+ ?column? 
+----------
+ init
+(1 row)
+
+CREATE TABLE stats_test(data text);
+-- function to wait for counters to advance
+CREATE FUNCTION wait_for_decode_stats(check_reset bool, check_spill_txns bool) RETURNS void AS $$
+DECLARE
+  start_time timestamptz := clock_timestamp();
+  updated bool;
+BEGIN
+  -- we don't want to wait forever; loop will exit after 30 seconds
+  FOR i IN 1 .. 300 LOOP
+
+    IF check_spill_txns THEN
+
+      -- check to see if all updates have been reset/updated
+      SELECT CASE WHEN check_reset THEN (spill_txns = 0)
+                  ELSE (spill_txns > 0)
+             END
+      INTO updated
+      FROM pg_stat_replication_slots WHERE slot_name='regression_slot_stats';
+
+    ELSE
+
+      -- check to see if all updates have been reset/updated
+      SELECT CASE WHEN check_reset THEN (total_txns = 0)
+                  ELSE (total_txns > 0)
+             END
+      INTO updated
+      FROM pg_stat_replication_slots WHERE slot_name='regression_slot_stats';
+
+    END IF;
+
+    exit WHEN updated;
+
+    -- wait a little
+    perform pg_sleep_for('100 milliseconds');
+
+    -- reset stats snapshot so we can test again
+    perform pg_stat_clear_snapshot();
+
+  END LOOP;
+
+  -- report time waited in postmaster log (where it won't change test output)
+  RAISE LOG 'wait_for_decode_stats delayed % seconds',
+    extract(epoch from clock_timestamp() - start_time);
+END
+$$ LANGUAGE plpgsql;
+-- non-spilled xact
+SET logical_decoding_work_mem to '64MB';
+INSERT INTO stats_test values(1);
+SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats', NULL, NULL, 'skip-empty-xacts', '1');
+ count 
+-------
+     3
+(1 row)
+
+SELECT wait_for_decode_stats(false, false);
+ wait_for_decode_stats 
+-----------------------
+ 
+(1 row)
+
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots;
+       slot_name       | spill_txns | spill_count | total_txns | total_bytes 
+-----------------------+------------+-------------+------------+-------------
+ regression_slot_stats | t          | t           | t          | t
+(1 row)
+
+RESET logical_decoding_work_mem;
+-- reset the slot stats, and wait for stats collector's total txn to reset
+SELECT pg_stat_reset_replication_slot('regression_slot_stats');
+ pg_stat_reset_replication_slot 
+--------------------------------
+ 
+(1 row)
+
+SELECT wait_for_decode_stats(true, false);
+ wait_for_decode_stats 
+-----------------------
+ 
+(1 row)
+
+SELECT slot_name, spill_txns, spill_count, total_txns, total_bytes FROM pg_stat_replication_slots;
+       slot_name       | spill_txns | spill_count | total_txns | total_bytes 
+-----------------------+------------+-------------+------------+-------------
+ regression_slot_stats |          0 |           0 |          0 |           0
+(1 row)
+
+-- spilling the xact
+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_stats', NULL, NULL, 'skip-empty-xacts', '1');
+ count 
+-------
+  5002
+(1 row)
+
+-- 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, true);
+ wait_for_decode_stats 
+-----------------------
+ 
+(1 row)
+
+SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count FROM pg_stat_replication_slots;
+       slot_name       | spill_txns | spill_count 
+-----------------------+------------+-------------
+ regression_slot_stats | t          | t
+(1 row)
+
+-- Ensure stats can be repeatedly accessed using the same stats snapshot. See
+-- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
+BEGIN;
+SELECT slot_name FROM pg_stat_replication_slots;
+       slot_name       
+-----------------------
+ regression_slot_stats
+(1 row)
+
+SELECT slot_name FROM pg_stat_replication_slots;
+       slot_name       
+-----------------------
+ regression_slot_stats
+(1 row)
+
+COMMIT;
+DROP FUNCTION wait_for_decode_stats(bool, bool);
+DROP TABLE stats_test;
+SELECT pg_drop_replication_slot('regression_slot_stats');
+ pg_drop_replication_slot 
+--------------------------
+ 
+(1 row)
+