查看Sqlserver索引使用情况(数据库中索引，表中索引)

转自：https://blog.csdn.net/weixin_46867655/article/details/106330669
索引能加快速度，一般人都知道这个。

但是索引也有另一面，就是索引是有开销的，每次update、delete、insert表的时候，都会维护相应的索引，把值维护到索引中去。所以索引并不是越多越好，建好索引之后需要定期的查看索引的使用，比如一条索引一次没被查过，但是被修改了几十万甚至上百万次，那么这些修改都是需要资源消耗的。同时也要占用磁盘空间，对于这些删掉。对于user_seeks次数很少，或者为0的索引，可以删除这些索引；那如何查询索引的使用情况呢？如下：

--1.要查看的数据库的索引
use vims_sc --要查看的数据库
 
select db_name(database_id) as N'数据库名称',
       object_name(a.object_id) as tbname,
       b.name N'索引名称',
       user_seeks N'用户索引查找次数',
       user_scans N'用户索引扫描次数',
       last_user_seek N'最后查找时间',
       last_user_scan N'最后扫描时间',
       rows as N'表中的行数'
	   into #tmp
from sys.dm_db_index_usage_stats a join 
     sys.indexes b
     on a.index_id = b.index_id
     and a.object_id = b.object_id
     join sysindexes c
     on c.id = b.object_id
where database_id=db_id('vims_sc')   ---改成要查看的数据库
and object_name(a.object_id) not like 'sys%'
order by user_seeks,user_scans,object_name(a.object_id)
 
select *from #tmp where tbname='AP_VC_Vaccine'

--2.查看表的索引使用情况====================================
SELECT TOP 1000
o.name AS 表名
, i.name AS 索引名
, i.index_id AS 索引id
, dm_ius.user_seeks AS 搜索次数
, dm_ius.user_scans AS 扫描次数
, dm_ius.user_lookups AS 查找次数
, dm_ius.user_updates AS 更新次数
, p.TableRows as 表行数
, 'DROP INDEX ' + QUOTENAME(i.name)
+ ' ON ' + QUOTENAME(s.name) + '.' + QUOTENAME(OBJECT_NAME(dm_ius.OBJECT_ID)) AS '删除语句'
FROM sys.dm_db_index_usage_stats dm_ius
INNER JOIN sys.indexes i ON i.index_id = dm_ius.index_id AND dm_ius.OBJECT_ID = i.OBJECT_ID
INNER JOIN sys.objects o ON dm_ius.OBJECT_ID = o.OBJECT_ID
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id
INNER JOIN (SELECT SUM(p.rows) TableRows, p.index_id, p.OBJECT_ID
FROM sys.partitions p GROUP BY p.index_id, p.OBJECT_ID) p
ON p.index_id = dm_ius.index_id AND dm_ius.OBJECT_ID = p.OBJECT_ID
WHERE OBJECTPROPERTY(dm_ius.OBJECT_ID,'IsUserTable') = 1
AND dm_ius.database_id = DB_ID()
--AND i.type_desc = 'nonclustered'--这里指定了索引的类型，聚集索引或者非聚集索引
AND i.is_primary_key = 0
AND i.is_unique_constraint = 0
and o.name='StockOut'   --需要查找的表名
ORDER BY (dm_ius.user_seeks + dm_ius.user_scans + dm_ius.user_lookups) ASC