Resolve Dependencies of Function-Based Indexes A function-based index depends on any
function that it is using. If the function or the specification of a package containing the
function is redefined (or if the index owner’s EXECUTE privilege is revoked), then the
following conditions hold:
解决基于函数索引依赖性，一个函数索引取决于这个索引上的任何函数。如果函数或者包含
函数的包体的定义重定义（或者如果索引的拥有者的EXECUTE权限被收回），那么以下条件将
保持 ：
■ The index is marked as DISABLED.
■ Queries on a DISABLED index fail if the optimizer chooses to use the index.
■ DML operations on a DISABLED index fail unless the index is also marked
UNUSABLE and the initialization parameter SKIP_UNUSABLE_INDEXES is set to
true.
To re-enable the index after a change to the function, use the ALTER INDEX ... ENABLE
statement.
#索引被标记为DISABLED.
#查询在DISABLED索引将失败如果优化器选择使用这个索引。
#DML操作在一个DISABLED索引上表将失败除非索引被标记为UNUSABLE并且初始化参数
SKIP_UNUSABLE_INDEXES设置为TRUE.
为了重新启动索引在一个函数改变后，可以使用ALTER INDEX...ENABLE语句。
---------------------------------------------操作记录-----------------------------------------------
SQL> update a set comoon='dd' where object_id=28;
update a set comoon='dd' where object_id=28
*
ERROR at line 1:
ORA-30554: function-based index AIKI.IDX_001 is disabled
SQL> alter index idx_001 unusable;
Index altered.
SQL> update a set comoon='dd' where object_id=28;
1 row updated.
SQL> rollback;
