查Postgresql 数据库、各表占用磁盘大小

统计各数据库占用磁盘大小：

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

统计数据库中各表占用磁盘大小：

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