vacuum.out

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

--
-- VACUUM
--
CREATE TABLE vactst (i INT);
INSERT INTO vactst VALUES (1);
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst VALUES (0);
SELECT count(*) FROM vactst;
 count 
-------
  2049
(1 row)

DELETE FROM vactst WHERE i != 0;
SELECT * FROM vactst;
 i 
---
 0
(1 row)

VACUUM FULL vactst;
UPDATE vactst SET i = i + 1;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst SELECT * FROM vactst;
INSERT INTO vactst VALUES (0);
SELECT count(*) FROM vactst;
 count 
-------
  2049
(1 row)

DELETE FROM vactst WHERE i != 0;
VACUUM FULL vactst;
DELETE FROM vactst;
SELECT * FROM vactst;
 i 
---
(0 rows)

DROP TABLE vactst;