postgresql数据库基本信息查看

切换至postgresql数据库用户pguser 或 postgres（根据自己实际情况）

1.   SELECT version();

２.对的

2. 查看数据库大小：

SELECT pg_size_pretty(pg_database_size('tianrun')) As fulldbsize;

3. 查看所有的数据库的大小：

 select pg_database.datname, pg_size_pretty (pg_database_size(pg_database.datname)) AS size from pg_database; 

4. 查看各数据库数据创建时间：

 select datname,(pg_stat_file(format('%s/%s/PG_VERSION',
 case
 when spcname='pg_default' then 'base'
 else 'pg_tblspc/'||t2.oid||'/PG_11_201804061/'
 end,
 t1.oid))).*
 from pg_database t1,pg_tablespace t2 where t1.dattablespace=t2.oid;

5.按占空间大小，顺序查看所有表的大小

 select relname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_tables where schemaname='public' order by pg_relation_size(relid) desc;

6. 按占空间大小，顺序查看索引大小

 select indexrelname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_indexes where schemaname='public' order by pg_relation_size(relid) desc;