CREATE EXTENSION tsm_system_time; CREATE TABLE test_tablesample (id int, name text); INSERT INTO test_tablesample SELECT i, repeat(i::text, 1000) FROM generate_series(0, 30) s(i); ANALYZE test_tablesample; -- It's a bit tricky to test SYSTEM_TIME in a platform-independent way. -- We can test the zero-time corner case ... SELECT count(*) FROM test_tablesample TABLESAMPLE system_time (0); -- ... and we assume that this will finish before running out of time: SELECT count(*) FROM test_tablesample TABLESAMPLE system_time (100000); -- bad parameters should get through planning, but not execution: EXPLAIN (COSTS OFF) SELECT id FROM test_tablesample TABLESAMPLE system_time (-1); SELECT id FROM test_tablesample TABLESAMPLE system_time (-1); -- fail, this method is not repeatable: SELECT * FROM test_tablesample TABLESAMPLE system_time (10) REPEATABLE (0); -- since it's not repeatable, we expect a Materialize node in these plans: EXPLAIN (COSTS OFF) SELECT * FROM (VALUES (0),(100000)) v(time), LATERAL (SELECT COUNT(*) FROM test_tablesample TABLESAMPLE system_time (100000)) ss; SELECT * FROM (VALUES (0),(100000)) v(time), LATERAL (SELECT COUNT(*) FROM test_tablesample TABLESAMPLE system_time (100000)) ss; EXPLAIN (COSTS OFF) SELECT * FROM (VALUES (0),(100000)) v(time), LATERAL (SELECT COUNT(*) FROM test_tablesample TABLESAMPLE system_time (time)) ss; SELECT * FROM (VALUES (0),(100000)) v(time), LATERAL (SELECT COUNT(*) FROM test_tablesample TABLESAMPLE system_time (time)) ss; CREATE VIEW vv AS SELECT * FROM test_tablesample TABLESAMPLE system_time (20); EXPLAIN (COSTS OFF) SELECT * FROM vv; DROP EXTENSION tsm_system_time; -- fail, view depends on extension