学习目标
表空间是数据的容器。掌握表空间的管理，包括创建表空间、删除表空间、重命名表空间、查看表空间的情况。
课程学习
通过使用表空间，管理员可以控制一个数据库安装的磁盘布局。
表空间对应于一个文件系统目录，假定数据库节点数据目录/pg_location/mount1/path1是用户拥有读写权限的空目录。
openGauss自带了两个表空间：pg_default和pg_global。
默认表空间pg_default：用来存储非共享系统表、用户表、用户表index、临时表、临时表index、内部临时表的默认表空间。对应存储目录为实例数据目录下的base目录。
共享表空间pg_global：用来存放共享系统表的表空间。对应存储目录为实例数据目录下的global目录。
课后作业
1、创建表空间t_tbspace、用户test，并使用test，在这个表空间上创建表t1
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 t_tbspace relative location 'tablespace/tbs1';
CREATE TABLESPACE
omm=# create user test identified by 'test@123';
NOTICE: The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# grant create on tablespace t_tbspace to test;
GRANT
omm=# \c omm test
Password for user test:
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "omm" as user "test".
omm=> create table t1(id int);
CREATE TABLE
2、查看表空间t_tbspace的oid和大小
omm=> select oid,* from pg_tablespace;
oid | spcname | spcowner | spcacl | spcoptions | spcmaxsize | relative
-------+------------+----------+------------------------+------------+------------+----------(3 rows)
1663 | pg_default | 10 | | | | f
1664 | pg_global | 10 | | | | f
16389 | t_tbspace | 10 | {omm=C/omm,test=C/omm} | | | t
omm=> select pg_tablespace_size('t_tbspace');
pg_tablespace_size
--------------------
4096
(1 row)
3、查看数据库在默认表空间下有哪些对象
omm=> with objectInDefaultTS as
omm-> ( select relname, relkind, relpages,pg_size_pretty(pg_relation_size(a.oid)),
omm(> reltablespace,relowner
omm(> from pg_class a
omm(> where a.relkind in ('r', 'i') and reltablespace='0'
omm(> )
omm-> select *
omm-> from objectInDefaultTS
%'m-> order by relpages desc; where relname not like 'pg_%' and relname not like 'gs_%' and relname not like 'sql_%
omm->
relname | relkind | relpages | pg_size_pretty | reltablespa
ce | relowner
------------------------------------------+---------+----------+----------------+------------
---+----------
streaming_gather_agg_index | i | 2 | 16 kB |
0 | 10
statement_history_time_idx | i | 1 | 8192 bytes |
0 | 10
snapshot_id_key | i | 1 | 8192 bytes |
0 | 10
streaming_cont_query_oid_index | i | 1 | 8192 bytes |
0 | 10
streaming_cont_query_matrelid_index | i | 1 | 8192 bytes |
0 | 10
streaming_cont_query_lookupidxid_index | i | 1 | 8192 bytes |
0 | 10
streaming_reaper_status_id_index | i | 1 | 8192 bytes |
0 | 10
streaming_cont_query_schema_change_index | i | 1 | 8192 bytes |
0 | 10
streaming_reaper_status_oid_index | i | 1 | 8192 bytes |
0 | 10
snapshot_pkey | i | 1 | 8192 bytes |
0 | 10
streaming_stream_oid_index | i | 1 | 8192 bytes |
0 | 10
streaming_stream_relid_index | i | 1 | 8192 bytes |
0 | 10
streaming_cont_query_relid_index | i | 1 | 8192 bytes |
0 | 10
streaming_cont_query_defrelid_index | i | 1 | 8192 bytes |
0 | 10
streaming_cont_query_id_index | i | 1 | 8192 bytes |
0 | 10
plan_table_data | r | 0 | 0 bytes |
0 | 10
statement_history | r | 0 | 0 bytes |
0 | 10
streaming_stream | r | 0 | 0 bytes |
0 | 10
streaming_reaper_status | r | 0 | 0 bytes |
0 | 10
snapshot | r | 0 | 0 bytes |
0 | 10
streaming_cont_query | r | 0 | 0 bytes |
0 | 10
t1 | r | 0 | 0 bytes |
0 | 16390
(22 rows)
4、查看数据库在非默认表空间下有哪些对象
omm=> select relname,relkind,relpages,pg_size_pretty(pg_relation_size(a.oid)),reltablespace,relowner
omm-> from pg_class a, pg_tablespace tb
omm-> omm-> where a.relkind in (‘r’, ‘i’)
and a.reltablespace=tb.oid
omm-> and tb.spcname=‘t_tbspace’
omm-> order by a.relpages desc;
relname | relkind | relpages | pg_size_pretty | reltablespace | relowner
---------±--------±---------±---------------±--------------±---------
(0 rows)
5、重命名表空间
omm=# alter tablespace t_tbspace rename to app_tbs;
ALTER TABLESPACE
omm=# \db
List of tablespaces
Name | Owner | Location
------------+-------+-----------------
pg_default | omm |
pg_global | omm |
app_tbs | omm | tablespace/tbs1
6、删除表空间
–用户必须是表空间的owner或者系统管理员才能删除表空间。需要先删除表空间的对象，再删除表空间
omm=# drop table test.t1;
DROP TABLE
omm=# drop tablespace app_tbs;
DROP TABLESPACE
