test18

如何使一个经常用的小表一直保留在内存中？

SQL> show parameter db%cache_size

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_keep_cache_size                   big integer 0  

SQL> select 10*1024*1024
  2  from dual;

10*1024*1024
------------
    10485760

Elapsed: 00:00:00.01
SQL> alter system set db_keep_cache_size=10485760;  <---指定Keep缓冲的大小

System altered.

Elapsed: 00:00:00.25

SQL> select sum(bytes)/1024/1024 M from user_segments where segment_name='T';

         M
----------
     .0625    <----该表的大小

Elapsed: 00:00:00.35
SQL> alter table t storage(buffer_pool keep);　　<--如此则可以将该表缓冲在keep中