11G新特性 -- 收缩临时表空间

当大任务执行完毕，并不会立即释放临时表空间。有时候通过删除然后重建临时表空间的速度可能更快。不过对于在线系统可能不会那么容易删除重建，所以11g中可以在线收缩临时表空间或单个临时数据文件。

收缩临时表空间

SQL> select name,blocks,bytes from v$tempfile;

NAME                                                   BLOCKS      BYTES
-------------------------------------------------- ---------- ----------
/u01/app/oracle/oradata/dbt/temp01.dbf                  40832  334495744

SQL> alter tablespace temp shrink space;

Tablespace altered.

SQL> select name,blocks,bytes from v$tempfile;

NAME                                                   BLOCKS      BYTES
-------------------------------------------------- ---------- ----------
/u01/app/oracle/oradata/dbt/temp01.dbf                    255    2088960

SQL> 

收缩单个临时数据文件

SQL> select name,blocks,bytes from v$tempfile;

NAME                                                   BLOCKS      BYTES
-------------------------------------------------- ---------- ----------
/u01/app/oracle/oradata/dbt/temp01.dbf                 262144 2147483648

SQL> alter tablespace temp shrink tempfile '/u01/app/oracle/oradata/dbt/temp01.dbf';

Tablespace altered.

SQL> select name,blocks,bytes from v$tempfile;

NAME                                                   BLOCKS      BYTES
-------------------------------------------------- ---------- ----------
/u01/app/oracle/oradata/dbt/temp01.dbf                    255    2088960

SQL> 

收缩到指定大小

SQL>  select name,blocks,bytes from v$tempfile;

NAME                                                   BLOCKS      BYTES
-------------------------------------------------- ---------- ----------
/u01/app/oracle/oradata/dbt/temp01.dbf                 262144 2147483648

SQL> alter tablespace temp shrink space keep 1g;

Tablespace altered.

SQL> select name,blocks,bytes from v$tempfile;

NAME                                                   BLOCKS      BYTES
-------------------------------------------------- ---------- ----------
/u01/app/oracle/oradata/dbt/temp01.dbf                 131072 1073741824

SQL>