查看数据库所占磁盘大小的几条命令。
表的大小 :

select pg_size_pretty(pg_relation_size('gp_test'));
 pg_size_pretty 
----------------
 1761 MB
(1 row)

表和索引的大小 :

select pg_size_pretty(pg_total_relation_size('gp_test'));
 pg_size_pretty 
----------------
 2186 MB
(1 row)

查看指定数据库大小 :

select pg_size_pretty(pg_database_size('zwcdb'));
 pg_size_pretty 
----------------
 2241 MB
(1 row)

查看所有数据库的大小 :

select datname,pg_size_pretty(pg_database_size(datname)) from pg_database;
  datname  | pg_size_pretty 
-----------+----------------
 zwcdb     | 2241 MB
 postgres  | 47 MB
 template1 | 47 MB
 template0 | 45 MB
 gpperfmon | 67 MB
(5 rows)

查看数据分布情况和磁盘空间 :

select gp_segment_id,count(*) from gp_test group by gp_segment_id order by 1;
 gp_segment_id |  count  
---------------+---------
             0 | 5000000
             1 | 4999999
             2 | 5000001
             3 | 5000000
(4 rows)
 
select dfhostname, dfspace,dfdevice from gp_toolkit.gp_disk_free order by dfhostname;
 dfhostname | dfspace  |  dfdevice  
------------+----------+------------
  sdw1      | 12273372 |  /dev/sdb1
  sdw1      | 12273372 |  /dev/sdb1
  sdw2      | 12273404 |  /dev/sdb1
  sdw2      | 12273404 |  /dev/sdb1