很多軟件開發(fā)過程中,，沒有注意合理規(guī)劃索引，造成一個表上有N多個索引,，為后續(xù)的維護(hù)和優(yōu)化帶來麻煩,。因 此有時候需要監(jiān)控已有的索引是否在使用,，oracle提供了監(jiān)控索引是否使用的工具，很簡單,，簡要介紹一下,。

首先，我們?nèi)绻潜O(jiān)控一個表上的所有索引,，可以這樣先生成監(jiān)控的命令：

SQL> select 'alter index '||index_name||' monitoring usage;' from user_indexes where table_name=upper('mpaymentappl')
2  /

'ALTERINDEX'||INDEX_NAME||'MONITORINGUSAGE;'
------------------------------------------------------------
alter index IDX_MPAYMENTAPPL_BCODE monitoring usage;
alter index MPAYMENTAPPL_FLAGS monitoring usage;
alter index MPAYMENTAPPL_PAICODE monitoring usage;

然后執(zhí)行這些腳本就開始監(jiān)控了,，監(jiān)控信息可通過V$OBJECT_USAGE查看，通過used列可知道這個索引是否被使用：

SQL> select * from V$OBJECT_USAGE
2  /

INDEX_NAME                     TABLE_NAME                     MON USE START_MONITORING    END_MONITORING
------------------------------ ------------------------------ --- --- ------------------- -------------------
IDX_MPAYMENTAPPL_BCODE         MPAYMENTAPPL                   YES NO  03/24/2010 10:55:27
MPAYMENTAPPL_FLAGS             MPAYMENTAPPL                   YES NO  03/24/2010 10:55:27
MPAYMENTAPPL_PAICODE           MPAYMENTAPPL                   YES NO  03/24/2010 10:55:28

取消監(jiān)控某個索引：

SQL> ALTER INDEX MPAYMENTAPPL_FLAGS NOMONITORING USAGE;

Index altered.

SQL> select * from V$OBJECT_USAGE
2  /

INDEX_NAME                     TABLE_NAME                     MON USE START_MONITORING    END_MONITORING
------------------------------ ------------------------------ --- --- ------------------- -------------------
IDX_MPAYMENTAPPL_BCODE         MPAYMENTAPPL                   YES NO  03/24/2010 10:55:27
MPAYMENTAPPL_FLAGS             MPAYMENTAPPL                   NO  NO  03/24/2010 10:55:27 03/24/2010 10:57:19
MPAYMENTAPPL_PAICODE           MPAYMENTAPPL                   YES NO  03/24/2010 10:55:28

那些持續(xù)關(guān)注一定時間沒有使用的索引就可以刪除了,，以提高DML操作效率,。