SQL Server数据库文件，自动扩展时最后剩余空间如果不满足扩展条件，系统不会自动再利用剩余容量，http://space.itpub.net/81227/viewspace-713277

以下测试在Oracle中是否也存在同样的问题。

SQL> conn / as sysdba

SQL> select * from v$version;

BANNER

--------------------------------------------------------------------------------

Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production

--创建一个初始10M，每次扩展30M，最大60M的表空间

SQL> create tablespace t_demo datafile '/home/oracle/oradata/zw/t_demo01.dbf' size 10M autoextend on next 30M maxsize 60M;

Tablespace created.

SQL> create table t_table as select * from dba_objects;

Table created.

SQL> alter table t_table move tablespace t_demo;

Table altered.

SQL> select FILE#,name ,BYTES ,BLOCKS,CREATE_BYTES,BLOCK_SIZE from v$datafile where file#=6;

FILE# NAMEBYTESBLOCKS CREATE_BYTES BLOCK_SIZE

---------- ------------ ---------- ---------- ------------ ----------

6 t_demo01.dbf104857601280104857608192

SQL> insert into t_table select * from t_table;

72339 rows created.

SQL> select FILE#,name ,BYTES ,BLOCKS,CREATE_BYTES,BLOCK_SIZE from v$datafile where file#=6;

FILE# NAMEBYTESBLOCKS CREATE_BYTES BLOCK_SIZE

---------- ------------ ---------- ---------- ------------ ----------

6 t_demo01.dbf 419430405120104857608192

--此处扩展了30M，总容量为40M

SQL> insert into t_table select * from t_table;

144678 rows created.

SQL> select FILE#,name ,BYTES ,BLOCKS,CREATE_BYTES,BLOCK_SIZE from v$datafile where file#=6;

FILE# NAMEBYTESBLOCKS CREATE_BYTES BLOCK_SIZE

---------- ------------ ---------- ---------- ------------ ----------

6 t_demo01.dbf 419430405120104857608192

SQL> select segment_name,bytes from dba_segments where segment_name='T_TABLE';

SEGMENT_NAMEBYTES

---------------- ----------

T_TABLE34603008

SQL> insert into t_table select * from t_table;

insert into t_table select * from t_table

*

ERROR at line 1:

ORA-01653: unable to extend table SYS.T_TABLE by 128 in tablespace T_DEMO

SQL> select segment_name,bytes from dba_segments where segment_name='T_TABLE';

SEGMENT_NAMEBYTES

---------------- ----------

T_TABLE61865984

SQL> select FILE#,name ,BYTES ,BLOCKS,CREATE_BYTES,BLOCK_SIZE from v$datafile where file#=6;

FILE# NAMEBYTESBLOCKS CREATE_BYTES BLOCK_SIZE

---------- ------------ ---------- ---------- ------------ ----------

6 t_demo01.dbf 629145607680104857608192

--此处扩展了20M，总容量为60M

SQL> select 7680*8/1024 from dual;

7680*8/1024

-----------

60

在Oracle中，数据文件自动扩展，最后会充分利用剩余的可用空间，使数据文件大小达到设定的最大容量。