When Oracle11G uses EXP to export, the empty table cannot be exported.

Oracle11G用EXP导出时,空表不能导出解决：

11G中有个新特性,当表无数据时,不分配segment,以节省空间

解决：
方法一：insert一行,再rollback就产生segment了
该方法是在在空表中插入数据,再删除,则产生segment.导出时则可导出空表.

方法二：设置deferred_segment_creation 参数

 show parameter deferred_segment_creation
  NAME                                 TYPE        VALUE
  ------------------------------------ ----------- ------------------------------
  deferred_segment_creation            boolean     TRUE

alter system set deferred_segment_creation=false;
  系统已更改.

show parameter deferred_segment_creation
  NAME                                 TYPE        VALUE
  ------------------------------------ ----------- ------------------------------
  deferred_segment_creation            boolean     FALSE

• 该参数值默认是TRUE,当改为FALSE时,无论是空表还是非空表,都分配segment.
• 注意：This value has no effect on previously imported empty tables,仍不能导出,Only works on newly added tables later.
• 如需导出之前的空表,只能用第一种方法.

方法三：

1. 先查询一下当前用户下的所有空表

    select table_name from user_tables where NUM_ROWS=0;

2. Use the following sentence to find an empty table

    select 'alter table '||table_name||' allocate extent;' from user_tables where num_rows=0

3. 把查询结果导出,执行导出的语句

'ALTERTABLE'||TABLE_NAME||'ALLOCATEEXTENT;'
 -----------------------------------------------------------
 alter table AQ$_AQ$_MEM_MC_H allocate extent;
 alter table AQ$_AQ$_MEM_MC_G allocate extent;
 alter table AQ$_AQ$_MEM_MC_I allocate extent;
 alter table AQ$_AQ_PROP_TABLE_T allocate extent;
 alter table AQ$_AQ_PROP_TABLE_H allocate extent;
 alter table AQ$_AQ_PROP_TABLE_G allocate extent;
 alter table AQ$_AQ_PROP_TABLE_I allocate extent;
 alter table AQ$_KUPC$DATAPUMP_QUETAB_T allocate extent;
 alter table AQ$_KUPC$DATAPUMP_QUETAB_H allocate extent;
 alter table AQ$_KUPC$DATAPUMP_QUETAB_G allocate extent;
 alter table AQ$_KUPC$DATAPUMP_QUETAB_I allocate extent;

 'ALTERTABLE'||TABLE_NAME||'ALLOCATEEXTENT;'
 -----------------------------------------------------------
 alter table AQ$_SYS$SERVICE_METRICS_TAB_T allocate extent;
 alter table AQ$_SYS$SERVICE_METRICS_TAB_H allocate extent;
 alter table AQ$_SYS$SERVICE_METRICS_TAB_G allocate extent;
 alter table AQ$_SYS$SERVICE_METRICS_TAB_I allocate extent;

4. 然后再执行

  exp 用户名/密码@数据库名 file=/home/oracle/exp.dmp log=/home/oracle/exp_smsrun.log
  exp camsjs/camsjs@orcl file=E:\CAMSJS0421.dmp owner=camsjs