openGauss每日一练第 8 天 | 一个数据库可以存储在多个表空间中

学习目标
学习表空间与数据库对象的关系。
在musicdb数据库中创建的所有的表，没有指定表空间的名字，因此都创建在数据库默认的表空间music_tbs中，当我们在musicdb数据库中创建表warehouse_t1的时候，明确指定在表空间ds_location1中创建时，这个表会存储在这个指定的表空间。即一个数据库中的对象，可以位于不同的表空间.

课后作业
1.创建表空间newtbs1、 ds_location1，查看表空间

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/newtbs1';
CREATE TABLESPACE
omm=# create tablespace ds_location1 relative location 'tablespace/ds_lc1';
CREATE TABLESPACE
omm=# \db
            List of tablespaces
     Name     | Owner |      Location      
--------------+-------+--------------------
 ds_location1 | omm   | tablespace/ds_lc1
 newtbs1      | omm   | tablespace/newtbs1
 pg_default   | omm   | 
 pg_global    | omm   | 
(4 rows)

2.创建一个数据库newdb1，默认表空间为newtbs1

omm=# create database newdb1 with  tablespace=newtbs1;
CREATE DATABASE

3.创建用户user5，并授予SYSADMIN权限，访问数据库newdb1，在表空间ds_location1上，创建一个表newt1（表结构自定义）

omm=# create user user5 identified by 'test@123';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# alter user user5 sysadmin;
ALTER ROLE

omm=# \c newdb1 user5
Password for user user5: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "newdb1" as user "user5".
newdb1=> create table newt1(id int) tablespace ds_location1;
CREATE TABLE

4.查看表所在的表空间

newdb1=> select * from pg_tables where tablename = 'newt1';


 schemaname | tablename | tableowner |  tablespace  | hasindexes | hasrules | hastriggers | tablecreator |       
     created            |         last_ddl_time         
------------+-----------+------------+--------------+------------+----------+-------------+--------------+-------
------------------------+-------------------------------
 public     | newt1     | user5      | ds_location1 | f          | f        | f           | user5        | 2022-1
2-01 11:15:47.281848+08 | 2022-12-01 11:15:47.281848+08

5.查看表空间newtbs1、 ds_location1上的对象

newdb1=> select relname, relkind, relpages,pg_size_pretty(pg_relation_size(a.oid)),reltablespace,relowner  
newdb1-> from pg_class a, pg_tablespace tb  
newdb1-> where a.relkind in ('r', 'i')  
newdb1-> and a.reltablespace=tb.oid  
newdb1-> and tb.spcname in ('newtbs1','ds_location1')
newdb1-> order by a.relpages desc;
 relname | relkind | relpages | pg_size_pretty | reltablespace | relowner 
---------+---------+----------+----------------+---------------+----------
 newt1   | r       |        0 | 0 bytes        |         16390 |    16392
(1 row)