表空间

Database数据库

Talespace表空间

Segment逻辑段：

extent扩展：空间分配的最小单位

Oracle block块：（io的最小单位）查询初始化参数可以查看

SQL> show parameter db_block_size

 

UNDOTBS1：撤销表空间

表空间

查询预定义表空间：

SQL> select TABLESPACE_NAME,CONTENTS from dba_tablespaces;

SQL> select FILE_NAME, TABLESPACE_NAME from dba_data_files;

创建新表空间：

SQL> create tablespace tbs01 datafile '/u01/app/oracle/oradata/orcl/tbs01.dbf' SIZE 10M AUTOEXTEND ON NEXT 10M MAXSIZE 100M;

在指定的表空间中创建表：

SQL> create table t1 tablespace tbs01 as select * from dba_objects where 1=0;

SQL> select bytes, blocks, extents, tablespace_name from dba_segments where segment_name='T1';

SQL> insert into t1 select * from dba_objects;

SQL> select bytes, blocks, extents, tablespace_name from dba_segments where segment_name='T1';

SQL> select extent_id, bytes, blocks from dba_extents where segment_name='T1';

SQL> insert into t1 select * from t1;

SQL> insert into t1 select * from t1;

SQL> insert into t1 select * from t1;

SQL> select bytes, blocks, extents, tablespace_name from dba_segments where segment_name='T1';

SQL> select extent_id, bytes, blocks from dba_extents where segment_name='T1';

SQL> insert into t1 select * from t1;                 空间不足，报错

SQL> rollback;

SQL> select bytes, blocks, extents, tablespace_name from dba_segments where segment_name='T1';             空间不释放

SQL> alter table t1 move;        释放空间

只读表空间：

SQL> alter tablespace tbs01 read write（only）;

SQL> delete t1;                  禁止dml

SQL> insert into t1 select * from t1;        禁止dml

SQL> create table t2 (x int) tablespace tbs01;         失败

SQL> alter table t1 add (x int);         成功

SQL> update t1 set x=1;           失败

SQL> drop table t1;           成功

dml和ddl的区别

改变表空间大小：

resize，autoextend，add datafile

删除表空间：

SQL> drop tablespace tbs01 including contents and datafile;