skip_unusable_indexparameter
alter session/system set skip_unusable_index = true/false ;
公司主营业务：网站建设、成都网站设计、移动网站开发等业务。帮助企业客户真正实现互联网宣传，提高企业的竞争能力。成都创新互联是一支青春激扬、勤奋敬业、活力青春激扬、勤奋敬业、活力澎湃、和谐高效的团队。公司秉承以“开放、自由、严谨、自律”为核心的企业文化，感谢他们对我们的高要求，感谢他们从不同领域给我们带来的挑战，让我们激情的团队有机会用头脑与智慧不断的给客户带来惊喜。成都创新互联推出鹤山免费做网站回馈大家。
The point :
1, if set to true, then allow DML on table with unusable indexes(and index partitions). Or set to false to disallow DML on table.
2, DML on tables with constraints which with unusable index status will failed because data maybe violated constraint if DML allowed.
3, if DML not referencing on index column, DML will successfull dispite of this parameter .
suppose index idx_job_emp is defined on column job.
alter session set skip_unusable_index = false ;
insert into emp( empno, job, deptno) values (1,'analyzer',10) ; -- false ,because index maintenance can not be skip.
insert into emp( empno, deptno) values (1,10) ; -- successfull , because index does not indexing NULL value key.
[@more@]网站题目：skip_unusable_indexparameter
文章地址：http://ybzwz.com/article/joddgo.html
