openGauss每日一练第 9 天 | openGauss 3.0.0数据库在线实训课程

作者：马顺华

从事运维管理工作多年，目前就职于某科技有限公司，熟悉运维自动化、OceanBase部署运维、MySQL 运维以及各种云平台技术和产品。并已获得OceanBase认证OBCA、OBCP证书。

第9天 | openGauss中一个表空间可以存储多个数据库

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

进一步学习表空间与数据库对象的关系，了解oid的含义。

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…

1）–连接数据库

su - omm
gsql -r

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=# 

2）–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;

omm=# drop DATABASE  IF EXISTS  musicdb;
NOTICE:  database "musicdb" does not exist, skipping
DROP DATABASE
omm=# drop DATABASE  IF EXISTS  musicdb1;
NOTICE:  database "musicdb1" does not exist, skipping
DROP DATABASE
omm=# drop DATABASE  IF EXISTS  musicdb2;
NOTICE:  database "musicdb2" does not exist, skipping
DROP DATABASE
omm=# drop DATABASE  IF EXISTS  musicdb3;
NOTICE:  database "musicdb3" does not exist, skipping
DROP DATABASE
omm=# drop tablespace IF EXISTS music_tbs;
NOTICE:  Tablespace "music_tbs" does not exist, skipping.
omm=# DROP TABLESPACE

omm=# drop tablespace IF EXISTS ds_location1;
NOTICE:  Tablespace "ds_location1" does not exist, skipping.
omm=# DROP TABLESPACE

omm=# 

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;

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

3）–执行下面的SQL语句，创建用户user1 ：

drop user IF EXISTS user1;

omm=# drop user  IF EXISTS  user1;
NOTICE:  role "user1" does not exist, skipping
DROP ROLE

CREATE USER user1 IDENTIFIED BY ‘kunpeng@1234’;

omm=# CREATE USER user1 IDENTIFIED BY 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# 

4）–授予user1数据库系统的SYSADMIN权限：

ALTER USER user1 SYSADMIN;

omm=# 
omm=# ALTER USER user1 SYSADMIN;
omm=# ALTER ROLE

2.使用sql查看数据库所在的表空间

1）–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;

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
 musicdb   |         16389 | music_tbs
 template0 |          1663 | pg_default
 musicdb1  |         16389 | music_tbs
 musicdb2  |         16389 | music_tbs
 musicdb3  |         16389 | music_tbs
 postgres  |          1663 | pg_default
omm=# (8 rows)


omm=# 

3.在文件系统中查看表空间中的多个数据库

2）–查看数据库、表空间的oid

select oid,datname from pg_database;

omm=# select oid,datname from pg_database;
  oid  |  datname  
-------+-----------
     1 | template1
 16384 | omm
 16390 | musicdb
 14555 | template0
 16391 | musicdb1
 16392 | musicdb2
 16393 | musicdb3
 14560 | postgres
(8 rows)

omm=# 

select oid,* from pg_tablespace ;

omm=# select oid,* from pg_tablespace ;
  oid  |  spcname   | spcowner | spcacl | spcoptions | spcmaxsize | relative 
-------+------------+----------+--------+------------+------------+----------
  1663 | pg_default |       10 |        |            |            | f
  1664 | pg_global  |       10 |        |            |            | f
 16389 | music_tbs  |       10 |        |            |            | t
(3 rows)

omm=# 

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

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
 musicdb   |         16389 | music_tbs
 template0 |          1663 | pg_default
 musicdb1  |         16389 | music_tbs
 musicdb2  |         16389 | music_tbs
 musicdb3  |         16389 | music_tbs
 postgres  |          1663 | pg_default
(8 rows)

omm=# 

3）–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

root@modb:~# cd /var/lib/opengauss/data/pg_tblspc/16389
root@modb:/var/lib/opengauss/data/pg_tblspc/16389# cd  PG_9.2*
root@modb:/var/lib/opengauss/data/pg_tblspc/16389/PG_9.2_201611171_gaussdb# ls
16390  16391  16392  16393  pgsql_tmp
root@modb:/var/lib/opengauss/data/pg_tblspc/16389/PG_9.2_201611171_gaussdb# 

#说明：xxxxx是表空间 music_tbs的oid

课程总结

1.创建表空间newtbs1

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

3.使用sql查看表空间newtbs1上有几个数据库

4.在文件系统中查看表空间newtbs1中的多个数据库