学习目标

进一步学习表空间与数据库对象的关系，了解oid的含义。

课程学习

1.创建表空间、多个数据库和用户

#第一次进入等待15秒
#数据库启动中...
su - omm
gsql -r

--进入数据库omm，创建表空间、测试数据库
drop DATABASE  IF EXISTS  musicdb;
drop DATABASE  IF EXISTS  musicdb1;
drop DATABASE  IF EXISTS  musicdb2;
drop DATABASE  IF EXISTS  musicdb3;
drop tablespace IF EXISTS music_tbs;
drop tablespace IF EXISTS ds_location1;


CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE DATABASE musicdb  WITH TABLESPACE = music_tbs;
CREATE DATABASE musicdb1 WITH TABLESPACE = music_tbs;
CREATE DATABASE musicdb2 WITH TABLESPACE = music_tbs;
CREATE DATABASE musicdb3 WITH TABLESPACE = music_tbs;

--执行下面的SQL语句，创建用户user1 ：
drop user  IF EXISTS  user1;

CREATE USER user1 IDENTIFIED BY 'kunpeng@1234';
  
--授予user1数据库系统的SYSADMIN权限：

ALTER USER user1 SYSADMIN;

2.使用sql查看数据库所在的表空间

--查看数据库所在的表空间，可以看到一个表空间可以有多个数据库

select datname,dattablespace,spcname from pg_database d, pg_tablespace t where d.dattablespace=t.oid;        

3.在文件系统中查看表空间中的多个数据库

--查看数据库、表空间的oid               

 select oid,datname from pg_database;

select oid,* from pg_tablespace ;

select datname,dattablespace,spcname from pg_database d, pg_tablespace t where d.dattablespace=t.oid; 

--从文件系统，查看music_tbs表空间oid，可以看到一个表空间可以有多个数据库
 
cd /var/lib/opengauss/data/pg_tblspc/xxxxx/
cd  PG_9.2* 
ls
 #说明：xxxxx是表空间 music_tbs的oid

实战演练

Welcome to 墨天轮.
This is Web Terminal of modb.pro; Good Good Study, Day Day Up.

课后作业

1.创建表空间newtbs1

root@modb:~# su  - omm
omm@modb:~$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=# CREATE TABLESPACE newtbs1 RELATIVE LOCATION 'tablespace/newtbs_ts1';
CREATE TABLESPACE

2.创建3个数据库newdb1、newdb2、newdb3，默认表空间为newtbs1

omm=# CREATE DATABASE newdb1 WITH TABLESPACE = newtbs1;
CREATE DATABASE
omm=# CREATE DATABASE newdb2 WITH TABLESPACE = newtbs1;
CREATE DATABASE
omm=# CREATE DATABASE newdb3 WITH TABLESPACE = newtbs1;
CREATE DATABASE
omm=# \l
                         List of databases
   Name    | Owner | Encoding | Collate | Ctype | Access privileges 
omm=# -----------+-------+----------+---------+-------+-------------------
 newdb1    | omm   | UTF8     | C       | C     | 
 newdb2    | omm   | UTF8     | C       | C     | 
 newdb3    | omm   | UTF8     | C       | C     | 
 omm       | omm   | UTF8     | C       | C     | 
 postgres  | omm   | UTF8     | C       | C     | 
 template0 | omm   | UTF8     | C       | C     | =c/omm           +
           |       |          |         |       | omm=CTc/omm
 template1 | omm   | UTF8     | C       | C     | =c/omm           +
           |       |          |         |       | omm=CTc/omm
(7 rows)

3.使用sql查看表空间newtbs1上有几个数据库

  
omm=# select datname,dattablespace,spcname from pg_database d, pg_tablespace t where d.dattablespace=t.oid; 
 omm       |          1663 | pg_default
  datname  | dattablespace |  spcname   
-----------+---------------+------------
 template1 |          1663 | pg_default
 newdb1    |         16389 | newtbs1
 template0 |          1663 | pg_default
 newdb2    |         16389 | newtbs1
 newdb3    |         16389 | newtbs1
 postgres  |          1663 | pg_default
(7 rows)

4.在文件系统中查看表空间newtbs1中的多个数据库

 select oid,datname from pg_database;
select oid,* from pg_tablespace ;
select datname,dattablespace,spcname from pg_database d, pg_tablespace t where d.dattablespace=t.oid;

omm=#  select oid,datname from pg_database;
omm=#   oid  |  datname  
-------+-----------
     1 | template1
 16384 | omm
 16394 | newdb1
 14555 | template0
 16395 | newdb2
 16396 | newdb3
 14560 | postgres
(7 rows)
omm=# select oid,* from pg_tablespace ;
  oid  |  spcname   | spcowner | spcacl | spcoptions | spcmaxsize | relative 
-------+------------+----------+--------+------------+------------+----------
  1663 | pg_default |       10 |        |            |            | f
  1664 | pg_global  |       10 |        |            |            | f
 16389 | newtbs1    |       10 |        |            |            | t
(3 rows)
omm=# select datname,dattablespace,spcname from pg_database d, pg_tablespace t where d.dattablespace=t.oid; 
  datname  | dattablespace |  spcname   
-----------+---------------+------------
 template1 |          1663 | pg_default
 omm       |          1663 | pg_default
 newdb1    |         16389 | newtbs1
 template0 |          1663 | pg_default
omm=#  newdb2    |         16389 | newtbs1
 newdb3    |         16389 | newtbs1
 postgres  |          1663 | pg_default
(7 rows)
omm@modb:~$ echo $PGDATA
/var/lib/opengauss/data 
omm@modb:~$ cd $PGDATA/pg_tblspc/
omm@modb:/var/lib/opengauss/data/pg_tblspc/16389$ ls
PG_9.2_201611171_gaussdb
omm@modb:/var/lib/opengauss/data/pg_tblspc/16389$