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
-----------
template1
omm
musicdb
template0
postgres
(5 rows)
omm-# \l
List of databases
Name | 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/omm
template1 | 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 schemas
Name | Owner | Access privileges | Description | WithBlockChain
-----------------+-------+-------------------+----------------------------------+----------------
blockchain | omm | | blockchain schema | f
cstore | omm | | reserved schema for DELTA tables | f
db4ai | omm | omm=UC/omm +| db4ai schema | f
| | =U/omm | |
dbe_perf | omm | | dbe_perf schema | f
dbe_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 | f
public | omm | omm=UC/omm +| standard public schema | f
snapshot | omm | | snapshot schema | f
sqladvisor | 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 TABLE
omm | dbe_pldeveloper | gs_errors | BASE TABLE
omm | 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=# \l
List of databases
Name | 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/omm
template1 | 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=# \l
List of databases
Name | 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/omm
template1 | 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.