第11天 |openGauss逻辑结构：数据库管理

接着昨天继续学习openGauss,今天是第11天了。今天学习内容是openGauss逻辑结构：表空间管理。
老规矩，先登陆墨天轮为我准备的实训实验室

root@modb:~# su - omm
omm@modb:~$ gsql -r

作业要求

1.创建表空间enmtbs和数据库musicdb

omm=# CREATE TABLESPACE enmtbs RELATIVE LOCATION 'tablespace/enmtbs1';
CREATE TABLESPACE
omm=# CREATE DATABASE musicdb WITH TABLESPACE = enmtbs;
CREATE DATABASE

2.查看数据库集簇中有哪些数据库

omm=# SELECT datname FROM pg_database;datname  
-----------template1ommmusicdbtemplate0postgres
(5 rows)omm-# \lList of databasesName    | Owner | Encoding | Collate | Ctype | Access privileges 
-----------+-------+----------+---------+-------+-------------------musicdb   | omm   | UTF8     | C       | C     | omm       | omm   | UTF8     | C       | C     | postgres  | omm   | UTF8     | C       | C     | template0 | omm   | UTF8     | C       | C     | =c/omm           +|       |          |         |       | omm=CTc/ommtemplate1 | omm   | UTF8     | C       | C     | =c/omm           +|       |          |         |       | omm=CTc/omm
(5 rows)

3.查看数据库默认的表空间信息

–首先执行下面的语句，查看musicdb数据库默认表空间的对象OID：

omm=# select datname,dattablespace from pg_database where datname='musicdb';datname | dattablespace 
---------+---------------musicdb |         16389
(1 row)

–根据表空间对象的OID，来查看表空间的名字：

omm=# select oid,spcname from pg_tablespace where oid=16389;oid  | spcname 
-------+---------16389 | enmtbs
(1 row)

–可以将上面的两条语句合并成一条语句，来查询数据库musicdb默认表空间的名字：

omm=# select spcname 
omm-# from pg_tablespace 
omm-# where oid=( select dattablespace
omm(#            from pg_database
omm(#            where datname='musicdb' )
omm-# ;spcname 
---------enmtbs
(1 row)

4.查看数据库下有哪些模式

omm-#\dn+List of schemasName       | Owner | Access privileges |           Description            | WithBlockChain 
-----------------+-------+-------------------+----------------------------------+----------------blockchain      | omm   |                   | blockchain schema                | fcstore          | omm   |                   | reserved schema for DELTA tables | fdb4ai           | omm   | omm=UC/omm       +| db4ai schema                     | f|       | =U/omm            |                                  | dbe_perf        | omm   |                   | dbe_perf schema                  | fdbe_pldebugger  | omm   | omm=UC/omm       +| dbe_pldebugger schema            | f|       | =U/omm            |                                  | dbe_pldeveloper | omm   | omm=UC/omm       +| dbe_pldeveloper schema           | f|       | =U/omm            |                                  | pkg_service     | omm   |                   | pkg_service schema               | fpublic          | omm   | omm=UC/omm       +| standard public schema           | fsnapshot        | omm   |                   | snapshot schema                  | fsqladvisor      | omm   | omm=UC/omm       +| sqladvisor schema                | f|       | =U/omm            |                                  | |       | =U/omm            |                                  | 
(10 rows)

5.查询当前连接的数据库下有哪些表：

omm=# with my_tables(table_catalog, table_schema, table_name, table_type) as
omm-#       (   select table_catalog, table_schema, table_name, table_type
omm(#           from information_schema.tables
omm(#          where table_schema not in ('pg_catalog', 'information_schema','dbe_perf')
omm(#        )
omm-# 
omm-#  select * from my_tables;table_catalog |  table_schema   | table_name | table_type 
---------------+-----------------+------------+------------omm           | db4ai           | snapshot   | BASE TABLEomm           | dbe_pldeveloper | gs_errors  | BASE TABLEomm           | dbe_pldeveloper | gs_source  | BASE TABLE
(3 rows)

6.更改数据库默认的表空间

omm=# CREATE TABLESPACE app_ts  RELATIVE LOCATION 'tablespace/app_ts1';
CREATE TABLESPACE
omm=# ALTER DATABASE musicdb  SET TABLESPACE app_ts;
ALTER DATABASE

–查看表空间是否更改完成

omm=# select spcname 
omm-# from pg_tablespace 
omm-# where oid=( select dattablespace
omm(#            from pg_database
omm(#            where datname='musicdb' );spcname 
---------app_ts
(1 row)

7.重新命名数据库

omm=# ALTER DATABASE musicdb RENAME TO  musicdb1;
ALTER DATABASE
omm=# \lList of databasesName    | Owner | Encoding | Collate | Ctype | Access privileges 
-----------+-------+----------+---------+-------+-------------------musicdb1  | omm   | UTF8     | C       | C     | omm       | omm   | UTF8     | C       | C     | postgres  | omm   | UTF8     | C       | C     | template0 | omm   | UTF8     | C       | C     | =c/omm           +|       |          |         |       | omm=CTc/ommtemplate1 | omm   | UTF8     | C       | C     | =c/omm           +|       |          |         |       | omm=CTc/omm
(5 rows)

8.修改数据库的默认用户

omm=# CREATE USER user1  IDENTIFIED BY 'user1@ustb2020';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# ALTER USER user1  SYSADMIN;
ALTER ROLE
omm=# ALTER DATABASE musicdb OWNER to user1;
ERROR:  database "musicdb" does not exist
omm=# \lList of databasesName    | Owner | Encoding | Collate | Ctype | Access privileges 
-----------+-------+----------+---------+-------+-------------------musicdb1  | omm   | UTF8     | C       | C     | omm       | omm   | UTF8     | C       | C     | postgres  | omm   | UTF8     | C       | C     | template0 | omm   | UTF8     | C       | C     | =c/omm           +|       |          |         |       | omm=CTc/ommtemplate1 | omm   | UTF8     | C       | C     | =c/omm           +|       |          |         |       | omm=CTc/omm
(5 rows)

9.删除数据库

omm=# DROP DATABASE musicdb1;
DROP DATABASE

总结

今天练习了关于数据库管理的几条命令，受益匪浅.