1.使用命令行方式查看用户自己的表。
[postgres@kevin root]$ psql -c "\d" -d kevin_test could not change directory to "/root" List of relations Schema | Name | Type | Owner --------+---------------+-------+---------------- public | tbl_test_port | table | pg_test_user_3 (1 row) [postgres@kevin root]$
2.查看当前数据库的大小,单位Byte.
kevin_test=# SELECT pg_database_size(current_database()); pg_database_size ------------------ 5431588 (1 row) kevin_test=#
3.查看服务器中所有数据库的大小。
kevin_test=# SELECT datname,pg_database_size(datname) from pg_database; datname | pg_database_size --------------------+------------------ template1 | 5316612 template0 | 5316612 postgres | 5415204 kevin_test | 5431588 pg_test_database_3 | 5316612 (5 rows) kevin_test=#
4.查看某张表的大小。
kevin_test=# SELECT pg_relation_size('tbl_test_port'); pg_relation_size ------------------ 8192 (1 row) kevin_test=#
b. 命令方式查询
kevin_test=# \dt+ tbl_test_port List of relations Schema | Name | Type | Owner | Size | Description --------+---------------+-------+----------------+------------+------------- public | tbl_test_port | table | pg_test_user_3 | 8192 bytes | (1 row) kevin_test=#
5.查看某表包括表索引、视图等引用在内的所有空间大小。
kevin_test=# SELECT pg_total_relation_size('tbl_test_port'); pg_total_relation_size ------------------------ 24576 (1 row) kevin_test=#
6.查看表中记录个数,由于count(*)在记录很多的情况下,效率较低,所以提供了一种估算的方式。
kevin_test=# SELECT count(*) from tbl_test_port; count ------- 12 (1 row) kevin_test=# kevin_test=# SELECT (CASE WHEN reltuples > 0 THEN pg_relation_size('tbl_test_port') / (8192 * relpages / reltuples) ELSE 0 END)::bigint as estimated_row_count FROM pg_class WHERE oid = 'tbl_test_port'::regclass; estimated_row_count --------------------- 0 (1 row) kevin_test=#
可以看出,在记录个数较少的情况下,结果不准确。