playboy=> \l                       //\加上字母l,相当于mysql的，mysql> show databases;

        List of databases

   Name    |  Owner   | Encoding

-----------+----------+----------

 playboy   | postgres | UTF8

 postgres  | postgres | UTF8

 template0 | postgres | UTF8

 template1 | postgres | UTF8

playboy=> select pg_database_size('playboy');    //查看playboy数据库的大小

 pg_database_size

------------------

          3637896

(1 row)

playboy=> select pg_database.datname, pg_database_size(pg_database.datname) AS size from pg_database;    //查看所有数据库的大小

  datname  |  size

-----------+---------

 postgres  | 3621512

 playboy   | 3637896

 template1 | 3563524

 template0 | 3563524

(4 rows)

playboy=> select pg_size_pretty(pg_database_size('playboy'));      //以KB，MB，GB的方式来查看数据库大小

 pg_size_pretty

----------------

 3553 kB

(1 row)

playboy=> \dt                      //相当于mysql的，mysql> show tables;

        List of relations

 Schema | Name | Type  |  Owner

--------+------+-------+---------

 public | test | table | playboy

(1 row)

playboy=> \d test;                 //相当于mysql的，mysql> desc test;

            Table "public.test"

 Column |         Type          | Modifiers

--------+-----------------------+-----------

 id     | integer               | not null

 name   | character varying(32) |

Indexes: "playboy_id_pk" PRIMARY KEY, btree (id)

playboy=> select pg_relation_size('test');   //查看表大小

 pg_relation_size

------------------

                0

(1 row)

playboy=> select pg_size_pretty(pg_relation_size('test'));   //以KB，MB，GB的方式来查看表大小

 pg_size_pretty

----------------

 0 bytes

(1 row)

playboy=> select pg_size_pretty(pg_total_relation_size('test'));   //查看表的总大小，包括索引大小

 pg_size_pretty

----------------

 8192 bytes

(1 row)

playboy=> \di                      //相当于mysql的，mysql> show index from test;

                List of relations

 Schema |     Name      | Type  |  Owner  | Table

--------+---------------+-------+---------+-------

 public | playboy_id_pk | index | playboy | test

(1 row)

playboy=> select pg_size_pretty(pg_relation_size('playboy_id_pk'));    //查看索大小

 pg_size_pretty

----------------

 8192 bytes

(1 row)

playboy=> select spcname from pg_tablespace;         //查看所有表空间

  spcname

------------

 pg_default

 pg_global

(2 rows)

playboy=> select pg_size_pretty(pg_tablespace_size('pg_default'));   //查看表空间大小

 pg_size_pretty

----------------

 14 MB

(1 row)

SELECT table_schema || '.' || table_name AS table_full_name, pg_size_pretty(pg_total_relation_size('"' || table_schema || '"."' || table_name || '"')) AS size

FROM information_schema.tables

ORDER BY pg_total_relation_size('"' || table_schema || '"."' || table_name || '"') DESC limit 20;

SELECT d.datname AS Name,  pg_catalog.pg_get_userbyid(d.datdba) AS Owner,

    CASE WHEN pg_catalog.has_database_privilege(d.datname, 'CONNECT')

        THEN pg_catalog.pg_size_pretty(pg_catalog.pg_database_size(d.datname))

        ELSE 'No Access'

    END AS SIZE

FROM pg_catalog.pg_database d

    ORDER BY

    CASE WHEN pg_catalog.has_database_privilege(d.datname, 'CONNECT')

        THEN pg_catalog.pg_database_size(d.datname)

        ELSE NULL

    END DESC -- nulls first

    LIMIT 20