postgresql/contrib/tsm_system_time/expected/tsm_system_time.out

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);
 count 
-------
     0
(1 row)

-- ... and we assume that this will finish before running out of time:
SELECT count(*) FROM test_tablesample TABLESAMPLE system_time (100000);
 count 
-------
    31
(1 row)

-- bad parameters should get through planning, but not execution:
EXPLAIN (COSTS OFF)
SELECT id FROM test_tablesample TABLESAMPLE system_time (-1);
                    QUERY PLAN                    
--------------------------------------------------
 Sample Scan on test_tablesample
   Sampling: system_time ('-1'::double precision)
(2 rows)

SELECT id FROM test_tablesample TABLESAMPLE system_time (-1);
ERROR:  sample collection time must not be negative
-- fail, this method is not repeatable:
SELECT * FROM test_tablesample TABLESAMPLE system_time (10) REPEATABLE (0);
ERROR:  tablesample method system_time does not support REPEATABLE
LINE 1: SELECT * FROM test_tablesample TABLESAMPLE system_time (10) ...
                                                   ^
-- 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;
                               QUERY PLAN                               
------------------------------------------------------------------------
 Nested Loop
   ->  Aggregate
         ->  Materialize
               ->  Sample Scan on test_tablesample
                     Sampling: system_time ('100000'::double precision)
   ->  Values Scan on "*VALUES*"
(6 rows)

SELECT * FROM
  (VALUES (0),(100000)) v(time),
  LATERAL (SELECT COUNT(*) FROM test_tablesample
           TABLESAMPLE system_time (100000)) ss;
  time  | count 
--------+-------
      0 |    31
 100000 |    31
(2 rows)

EXPLAIN (COSTS OFF)
SELECT * FROM
  (VALUES (0),(100000)) v(time),
  LATERAL (SELECT COUNT(*) FROM test_tablesample
           TABLESAMPLE system_time (time)) ss;
                           QUERY PLAN                           
----------------------------------------------------------------
 Nested Loop
   ->  Values Scan on "*VALUES*"
   ->  Aggregate
         ->  Materialize
               ->  Sample Scan on test_tablesample
                     Sampling: system_time ("*VALUES*".column1)
(6 rows)

SELECT * FROM
  (VALUES (0),(100000)) v(time),
  LATERAL (SELECT COUNT(*) FROM test_tablesample
           TABLESAMPLE system_time (time)) ss;
  time  | count 
--------+-------
      0 |     0
 100000 |    31
(2 rows)

CREATE VIEW vv AS
  SELECT * FROM test_tablesample TABLESAMPLE system_time (20);
EXPLAIN (COSTS OFF) SELECT * FROM vv;
                    QUERY PLAN                    
--------------------------------------------------
 Sample Scan on test_tablesample
   Sampling: system_time ('20'::double precision)
(2 rows)

DROP EXTENSION tsm_system_time;  -- fail, view depends on extension
ERROR:  cannot drop extension tsm_system_time because other objects depend on it
DETAIL:  view vv depends on function system_time(internal)
HINT:  Use DROP ... CASCADE to drop the dependent objects too.