【转】如何新建索引:高开销的缺失索引

转自http://blog.csdn.net/yangzhawen/article/details/7253746

索引对查询性能影响极大，不要盲目的新建索引！数据库高开销的缺失索引 ,根据对动态性能视图的统计信息，新建需要的索引！

select c.name as 库名,c.equality_columns,
c.inequality_columns,c.included_columns,
c.statement as 表名,
c.avg_total_user_cost as 减少的平均成本 ,
c.avg_user_impact as 百分比收益,
c.last_user_seek as 使用后影响上次结果,
c.unique_compiles
from 
(
select a.name,b.* from 
(
select d.*
        , s.avg_total_user_cost
        , s.avg_user_impact
        , s.last_user_seek
        ,s.unique_compiles
from sys.dm_db_missing_index_group_stats s
        ,sys.dm_db_missing_index_groups g
        ,sys.dm_db_missing_index_details d
where s.group_handle = g.index_group_handle
and d.index_handle = g.index_handle
--order by s.avg_user_impact desc
)  b,
sys.databases a 
where a.database_id=b.database_id
)c
order by 百分比收益 desc,unique_compiles desc