openGauss每日一练第 10 天

原创陶笑 2022-12-03

214

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

newdb1=# CREATE TABLESPACE   t_tbspace  RELATIVE LOCATION 'tablespace/t_tbspace_ts1';
CREATE TABLESPACE
newdb1=# CREATE USER test IDENTIFIED BY 'test54321!';
CREATE ROLE
newdb1=# GRANT CREATE ON TABLESPACE t_tbspace TO test;
GRANT
newdb1=# CREATE TABLE t1(id number) TABLESPACE t_tbspace;
CREATE TABLE
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2、查看表空间t_tbspace的oid和大小

pg_tablespace_size计算表空间占用的磁盘空间，单位是bytes

--可以根据名字
newdb1=# select oid,spcname,PG_TABLESPACE_SIZE('t_tbspace') from pg_tablespace ;
  oid  |  spcname   | pg_tablespace_size
-------+------------+--------------------
  1663 | pg_default |               8243
  1664 | pg_global  |               8243
 16390 | music_tbs  |               8243
 24679 | newtbs1    |               8243
 24683 | t_tbspace  |               8243
--也可以根据oid
newdb1=# select  PG_TABLESPACE_SIZE(24683);
 pg_tablespace_size
--------------------
               8243
(1 row)

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3、查看数据库在默认表空间下有哪些对象

newdb1-#  select *
newdb1-#  from objectInDefaultTS
newdb1-#    where relname not like 'pg_%' and relname not like 'gs_%' and relname not like 'sql_%'
newdb1-#  order by relpages desc;
                 relname                  | relkind | relpages | pg_size_pretty | reltablespace | 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_matrelid_index      | i       |        1 | 8192 bytes     |             0 |       10
 streaming_cont_query_lookupidxid_index   | i       |        1 | 8192 bytes     |             0 |       10
 streaming_cont_query_schema_change_index | i       |        1 | 8192 bytes     |             0 |       10
 streaming_reaper_status_id_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
 streaming_cont_query_oid_index           | i       |        1 | 8192 bytes     |             0 |       10
 plan_table_data                          | 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
 statement_history                        | r       |        0 | 0 bytes        |             0 |       10
(21 rows)
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4、查看数据库在非默认表空间下有哪些对象

--查看t_tbspace表空间下的对象，还是根据pg_class和pg_tablespace的tbs的oid关联进行查询，因为不是默认表空间，所以这里oid不是0可以关联

newdb1=#  select relname,relkind,relpages,pg_size_pretty(pg_relation_size(a.oid)),
newdb1-#           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='t_tbspace'
newdb1-#    order by a.relpages desc;
       relname        | relkind | relpages | pg_size_pretty | reltablespace | relowner
----------------------+---------+----------+----------------+---------------+----------
 pg_toast_24688_index | i       |        1 | 8192 bytes     |         24683 |       10
 t1                   | r       |        0 | 0 bytes        |         24683 |       10
(2 rows)

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5、重命名表空间

语法：

  AlterTablespace ::= ALTER TABLESPACE tablespace_name  RENAME TO new_tablespace_name;
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newdb1=# \db
              List of tablespaces
    Name    | Owner |         Location
------------+-------+--------------------------
 music_tbs  | omm   | tablespace/test_ts1
 newtbs1    | omm   | tablespace/newtbs1_ts1
 pg_default | omm   |
 pg_global  | omm   |
 t_tbspace  | omm   | tablespace/t_tbspace_ts1
(5 rows)

newdb1=# ALTER TABLESPACE t_tbspace RENAME TO t_tbspace_new;
ALTER TABLESPACE
newdb1=# \db
               List of tablespaces
     Name      | Owner |         Location
---------------+-------+--------------------------
 music_tbs     | omm   | tablespace/test_ts1
 newtbs1       | omm   | tablespace/newtbs1_ts1
 pg_default    | omm   |
 pg_global     | omm   |
 t_tbspace_new | omm   | tablespace/t_tbspace_ts1
(5 rows)
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6、删除表空间

语法:

DropTablespace ::= DROP TABLESPACE [ IF EXISTS ] tablespace_name;
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这里要注意必须先删除表空间中的对象
否则会报错

newdb1=# drop tablespace t_tbspace_new;
ERROR:  tablespace "t_tbspace_new" is not empty

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需要先检查表空间下的对象，删除后，再删除表空间

newdb1=#  select relname,relkind,relpages,pg_size_pretty(pg_relation_size(a.oid)),
          reltablespace,relowner
   from pg_class a, pg_tablespace tb
   where a.relkind in ('r', 'i')
   and a.reltablespace=tb.oid
   and tb.spcname='t_tbspace_new'
   order by a.relpages desc;
       relname        | relkind | relpages | pg_size_pretty | reltablespace | relowner
----------------------+---------+----------+----------------+---------------+----------
 pg_toast_24688_index | i       |        1 | 8192 bytes     |         24683 |       10
 t1                   | r       |        0 | 0 bytes        |         24683 |       10
(2 rows)

newdb1=#
newdb1=# drop table t1;
DROP TABLE
newdb1=#  select relname,relkind,relpages,pg_size_pretty(pg_relation_size(a.oid)),
          reltablespace,relowner
   from pg_class a, pg_tablespace tb
   where a.relkind in ('r', 'i')
   and a.reltablespace=tb.oid
   and tb.spcname='t_tbspace_new'
   order by a.relpages desc;
 relname | relkind | relpages | pg_size_pretty | reltablespace | relowner
---------+---------+----------+----------------+---------------+----------
(0 rows)

newdb1=# drop tablespace t_tbspace_new;
DROP TABLESPACE
newdb1=# \db
             List of tablespaces
    Name    | Owner |        Location
------------+-------+------------------------
 music_tbs  | omm   | tablespace/test_ts1
 newtbs1    | omm   | tablespace/newtbs1_ts1
 pg_default | omm   |
 pg_global  | omm   |
(4 rows)



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