40 lines
1.3 KiB
SQL
40 lines
1.3 KiB
SQL
CREATE EXTENSION tsm_system_rows;
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CREATE TABLE test_tablesample (id int, name text);
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INSERT INTO test_tablesample SELECT i, repeat(i::text, 1000)
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FROM generate_series(0, 30) s(i);
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ANALYZE test_tablesample;
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SELECT count(*) FROM test_tablesample TABLESAMPLE system_rows (0);
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SELECT count(*) FROM test_tablesample TABLESAMPLE system_rows (1);
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SELECT count(*) FROM test_tablesample TABLESAMPLE system_rows (10);
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SELECT count(*) FROM test_tablesample TABLESAMPLE system_rows (100);
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-- bad parameters should get through planning, but not execution:
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EXPLAIN (COSTS OFF)
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SELECT id FROM test_tablesample TABLESAMPLE system_rows (-1);
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SELECT id FROM test_tablesample TABLESAMPLE system_rows (-1);
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-- fail, this method is not repeatable:
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SELECT * FROM test_tablesample TABLESAMPLE system_rows (10) REPEATABLE (0);
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-- but a join should be allowed:
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EXPLAIN (COSTS OFF)
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SELECT * FROM
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(VALUES (0),(10),(100)) v(nrows),
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LATERAL (SELECT count(*) FROM test_tablesample
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TABLESAMPLE system_rows (nrows)) ss;
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SELECT * FROM
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(VALUES (0),(10),(100)) v(nrows),
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LATERAL (SELECT count(*) FROM test_tablesample
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TABLESAMPLE system_rows (nrows)) ss;
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CREATE VIEW vv AS
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SELECT count(*) FROM test_tablesample TABLESAMPLE system_rows (20);
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SELECT * FROM vv;
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DROP EXTENSION tsm_system_rows; -- fail, view depends on extension
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