修改表（数据库）的表空间

作者：瀚高PG实验室 （Highgo PG Lab）- 天蝎座 

1、将表mytable迁移到新建表空间test2下（表空间test2的路径为/home/highgo/tbs2）

查询表内容：
highgo=# select * from mytable ;
 id 
----
  1
  2
  3
(3 rows)

创建表空间test2并迁移mytable到test2下：

highgo=# create tablespace test2 location '/home/highgo/tbs2';
CREATE TABLESPACE
highgo=# alter table mytable set tablespace test2;
ALTER TABLE

查询是否迁移成功
highgo=# select pg_relation_filepath ('mytable');
             pg_relation_filepath             
----------------------------------------------
 pg_tblspc/49442/PG_9.5_201510051/13351/49443
(1 row)
[highgo@hgdb pg_tblspc]$ pwd
/data/data/pg_tblspc
[highgo@hgdb pg_tblspc]$ ll
lrwxrwxrwx 1 highgo highgo 17 Dec 18 13:49 49442 -> /home/highgo/tbs2
drwx------ 3 highgo highgo 30 Dec  7 14:04 tmp



highgo=# select tablename,tablespace from pg_tables where tablename in ('mytable');
 tablename | tablespace 
-----------+------------
 mytable   | test2
(1 row)


将表mytable迁移到默认表空间：

highgo=# alter table mytable set tablespace pg_default;
ALTER TABLE
highgo=# select tablename,tablespace from pg_tables where tablename in ('mytable');
 tablename | tablespace 
-----------+------------
 mytable   | 
(1 row)

2、将highgo数据库的所有对象都移动到test2表空间中.

highgo=# select * from mytable2;
 id 
----
  4
  5
  6
(3 rows)

highgo=# alter database highgo set tablespace test2;
ERROR:  55006: cannot change the tablespace of the currently open database

test=# alter database highgo set tablespace test2;
ALTER DATABASE

highgo=# select pg_relation_filepath('mytable');
             pg_relation_filepath             
----------------------------------------------
 pg_tblspc/49442/PG_9.5_201510051/13351/49444
(1 row)

highgo=# select pg_relation_filepath('mytable2');
             pg_relation_filepath             
----------------------------------------------
 pg_tblspc/49442/PG_9.5_201510051/13351/49445
(1 row)

[highgo@hgdb pg_tblspc]$ pwd
/data/data/pg_tblspc
[highgo@hgdb pg_tblspc]$ ll
lrwxrwxrwx 1 highgo highgo 17 Dec 18 13:49 49442 -> /home/highgo/tbs2
drwx------ 3 highgo highgo 30 Dec  7 14:04 tmp

如上所示：mytable和mytable2 都已经迁移到了test2表空间下。