Add test for restoring pgstat file

test_runner/regress/test_pgstat.py

@@ -0,0 +1,39 @@
+from fixtures.neon_fixtures import NeonEnv
+from fixtures.pg_version import PgVersion
+
+#
+# Test that pgstat statistic is preserved across sessions
+#
+def test_pgstat(neon_simple_env: NeonEnv):
+    env = neon_simple_env
+    if env.pg_version == PgVersion.V14:
+        pytest.skip("PG14 doesn't support pgstat statistic persistence")
+
+    n = 10000
+    env.neon_cli.create_branch("test_pgstat", "empty")
+    endpoint = env.endpoints.create_start("test_pgstat")
+
+    con = endpoint.connect()
+    cur = con.cursor()
+
+    cur.execute("create table t(x integer)")
+    cur.execute(f"insert into t values (generate_series(1,{n}))")
+    cur.execute("vacuum analyze t")
+    cur.execute("select sum(x) from t")
+    cur.execute("update t set x=x+1")
+
+    cur.execute("select pg_stat_force_next_flush()")
+
+    cur.execute("select seq_scan,seq_tup_read,n_tup_ins,n_tup_upd,n_tup_newpage_upd,n_live_tup,n_dead_tup, vacuum_count,analyze_count from pg_stat_user_tables")
+    rec = cur.fetchall()[0]
+    assert rec[0]==2 and rec[1]==n*2 and rec[2]==n and rec[3]==n and rec[4]==n and rec[5]==n*2 and rec[6]==n and rec[7]==1 and rec[8]==1;
+
+    endpoint.stop();
+    endpoint.start();
+
+    con = endpoint.connect()
+    cur = con.cursor()
+
+    cur.execute("select seq_scan,seq_tup_read,n_tup_ins,n_tup_upd,n_tup_newpage_upd,n_live_tup,n_dead_tup, vacuum_count,analyze_count from pg_stat_user_tables")
+    rec = cur.fetchall()[0]
+    assert rec[0]==2 and rec[1]==n*2 and rec[2]==n and rec[3]==n and rec[4]==n and rec[5]==n*2 and rec[6]==n and rec[7]==1 and rec[8]==1;