@喬的回答似乎是正確的,我只是增加了一些可能的,有用的信息:
有使用此計算得到全部測試衝擊值的文章here:
avg_total_user_cost * avg_user_impact * (migs.user_seeks + migs.user_scans))
以下是他們建議的查詢:
SELECT CONVERT (varchar, getdate(), 126) AS runtime,
mig.index_group_handle, mid.index_handle,
CONVERT (decimal (28,1), migs.avg_total_user_cost * migs.avg_user_impact *
(migs.user_seeks + migs.user_scans)) AS improvement_measure,
'CREATE INDEX missing_index_' + CONVERT (varchar, mig.index_group_handle) + '_' +
CONVERT (varchar, mid.index_handle) + ' ON ' + mid.statement + '
(' + ISNULL (mid.equality_columns,'')
+ CASE WHEN mid.equality_columns IS NOT NULL
AND mid.inequality_columns IS NOT NULL
THEN ',' ELSE '' END + ISNULL (mid.inequality_columns, '')
+ ')'
+ ISNULL (' INCLUDE (' + mid.included_columns + ')', '') AS create_index_statement,
migs.*,
mid.database_id,
mid.[object_id]
FROM sys.dm_db_missing_index_groups AS mig
INNER JOIN sys.dm_db_missing_index_group_stats AS migs
ON migs.group_handle = mig.index_group_handle
INNER JOIN sys.dm_db_missing_index_details AS mid
ON mig.index_handle = mid.index_handle
ORDER BY migs.avg_total_user_cost * migs.avg_user_impact * (migs.user_seeks + migs.user_scans) DESC
由此產生的improvement_measure
是uni tless,即只在相對意義上有用,但這應該有助於將來自dm_db_missing_index_group_stats
的不同值合併成有用的決策依據。
你有一個很好的查詢來找到缺少的索引? – 2014-11-28 14:15:09
這裏有一個很好的:http://www.geniiius.com/blog/missing-indexes – 2014-11-28 15:53:36