当我运行SQL Server 2005数据库优化顾问时,它提供了一个建议来创建一个索引,但它会建议索引一个已经有索引的列。为什么它会建议再次创建相同的索引?数据库优化顾问建议创建一个现有索引
这里是我的SQL:
SELECT t.name AS 'affected_table'
, 'Create NonClustered Index IX_' + t.name + '_'
+ CAST(ddmid.index_handle AS VARCHAR(10))
+ ' On ' + ddmid.STATEMENT
+ ' (' + IsNull(ddmid.equality_columns,'')
+ CASE
WHEN ddmid.equality_columns IS NOT NULL
AND ddmid.inequality_columns IS NOT NULL
THEN ','
ELSE ''
END
+ ISNULL(ddmid.inequality_columns, '')
+ ')'
+ ISNULL(' Include (' + ddmid.included_columns + ');', ';')
AS sql_statement
, ddmigs.user_seeks
, ddmigs.user_scans
, CAST((ddmigs.user_seeks + ddmigs.user_scans)
* ddmigs.avg_user_impact AS INT) AS 'est_impact'
, ddmigs.last_user_seek
FROM
sys.dm_db_missing_index_groups AS ddmig
INNER JOIN sys.dm_db_missing_index_group_stats AS ddmigs
ON ddmigs.group_handle = ddmig.index_group_handle
INNER JOIN sys.dm_db_missing_index_details AS ddmid
ON ddmig.index_handle = ddmid.index_handle
INNER Join sys.tables AS t
ON ddmid.OBJECT_ID = t.OBJECT_ID
WHERE
ddmid.database_id = DB_ID()
AND CAST((ddmigs.user_seeks + ddmigs.user_scans)
* ddmigs.avg_user_impact AS INT) > 100
ORDER BY
CAST((ddmigs.user_seeks + ddmigs.user_scans)
* ddmigs.avg_user_impact AS INT) DESC;
您能否提供您当前的索引结构(即索引构建语句的脚本)和DTA提出的建议的详细信息。我怀疑你会发现他们是不同的。 – 2009-07-12 09:34:25
[为什么SQL Server 2005动态管理视图报告缺少索引时,它不是?](http://stackoverflow.com/questions/305524/why-does-sql-server-2005-dynamic-management- view-report-a-missing-index-when-it) – 2013-12-27 19:32:22