Sql Server 索引使用情况

--查询数据库索引碎片状况 use dbname; SELECT OBJECT_NAME(ind.OBJECT_ID) AS TableName,  ind.name AS IndexName, indexstats.index_type_desc AS IndexType,  indexstats.avg_fragmentation_in_percent  FROM sys.dm_db_index_physical_stats(DB_ID(), NULL, NULL, NULL, NULL) indexstats  INNER JOIN sys.indexes ind   ON ind.object_id = indexstats.object_id  AND ind.index_id = indexstats.index_id  WHERE indexstats.avg_fragmentation_in_percent > 50  ORDER BY indexstats.avg_fragmentation_in_percent DESC ;
--查询数据库索引使用状况 select db_name(database_id) as N'数据库名称',           object_name(a.object_id) as N'表名称',           b.name N'索引名称',         user_seeks N'索引查找次数',         user_scans N'索引扫描次数',         last_user_seek N'索引最后查找时间',        last_user_scan N'索引最后扫描时间',         rows as N'索引所属表行数' 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()   ---当前数据库 -- and object_name(a.object_id)   like 'test%' ---待检索表名  order by user_seeks,user_scans,object_name(a.object_id)

--查看那些被大量更新却很少被使用的索引，这类索引应该被移除 SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED SELECT                                                       DB_NAME() AS DatabaseName     , SCHEMA_NAME(o.Schema_ID) AS SchemaName     , OBJECT_NAME(s.[object_id]) AS TableName     , i.name AS IndexName     , s.user_updates     , s.system_seeks + s.system_scans + s.system_lookups                           AS [System usage] INTO #TempUnusedIndexes FROM   sys.dm_db_index_usage_stats s INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id]     AND s.index_id = i.index_id INNER JOIN sys.objects o ON i.object_id = O.object_id   WHERE 1=2 EXEC sp_MSForEachDB 'USE [?];                           INSERT INTO #TempUnusedIndexes SELECT TOP 20     DB_NAME() AS DatabaseName     , SCHEMA_NAME(o.Schema_ID) AS SchemaName     , OBJECT_NAME(s.[object_id]) AS TableName     , i.name AS IndexName     , s.user_updates     , s.system_seeks + s.system_scans + s.system_lookups                                          AS [System usage] FROM   sys.dm_db_index_usage_stats s INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id]     AND s.index_id = i.index_id INNER JOIN sys.objects o ON i.object_id = O.object_id   WHERE s.database_id = DB_ID() AND OBJECTPROPERTY(s.[object_id], ''IsMsShipped'') = 0 AND s.user_seeks = 0     AND s.user_scans = 0     AND s.user_lookups = 0 AND i.name IS NOT NULL ORDER BY s.user_updates DESC'                           SELECT TOP 20 * FROM #TempUnusedIndexes ORDER BY [user_updates] DESC DROP TABLE #TempUnusedIndexes
--最高维护代价的索引，Maintenance cost高的应该被移除
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED SELECT                                                         DB_NAME() AS DatabaseName     , SCHEMA_NAME(o.Schema_ID) AS SchemaName     , OBJECT_NAME(s.[object_id]) AS TableName     , i.name AS IndexName     , (s.user_updates ) AS [update usage]     , (s.user_seeks + s.user_scans + s.user_lookups) AS [Retrieval usage]     , (s.user_updates) -       (s.user_seeks + s.user_scans + s.user_lookups) AS [Maintenance cost]     , s.system_seeks + s.system_scans + s.system_lookups AS [System usage]     , s.last_user_seek     , s.last_user_scan     , s.last_user_lookup INTO #TempMaintenanceCost FROM   sys.dm_db_index_usage_stats s INNER JOIN sys.indexes i ON  s.[object_id] = i.[object_id]     AND s.index_id = i.index_id INNER JOIN sys.objects o ON i.object_id = O.object_id   WHERE 1=2 EXEC sp_MSForEachDB 'USE [?];                             INSERT INTO #TempMaintenanceCost SELECT TOP 20     DB_NAME() AS DatabaseName     , SCHEMA_NAME(o.Schema_ID) AS SchemaName     , OBJECT_NAME(s.[object_id]) AS TableName     , i.name AS IndexName     , (s.user_updates ) AS [update usage]     , (s.user_seeks + s.user_scans + s.user_lookups)                     AS [Retrieval usage]     , (s.user_updates) - (s.user_seeks + user_scans +                          s.user_lookups) AS [Maintenance cost]     , s.system_seeks + s.system_scans + s.system_lookups AS [System usage]     , s.last_user_seek     , s.last_user_scan     , s.last_user_lookup FROM   sys.dm_db_index_usage_stats s INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id]     AND s.index_id = i.index_id INNER JOIN sys.objects o ON i.object_id = O.object_id   WHERE s.database_id = DB_ID()     AND i.name IS NOT NULL     AND OBJECTPROPERTY(s.[object_id], ''IsMsShipped'') = 0     AND (s.user_seeks + s.user_scans + s.user_lookups) > 0 ORDER BY [Maintenance cost] DESC'                       SELECT top 20 * FROM #TempMaintenanceCost ORDER BY [Maintenance cost] DESC DROP TABLE #TempMaintenanceCost

--使用频繁的索引，这类索引不应被移除 SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED SELECT                                               DB_NAME() AS DatabaseName         , SCHEMA_NAME(o.Schema_ID) AS SchemaName     , OBJECT_NAME(s.[object_id]) AS TableName     , i.name AS IndexName     , (s.user_seeks + s.user_scans + s.user_lookups) AS [Usage]     , s.user_updates     , i.fill_factor INTO #TempUsage FROM sys.dm_db_index_usage_stats s INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id]     AND s.index_id = i.index_id INNER JOIN sys.objects o ON i.object_id = O.object_id   WHERE 1=2 EXEC sp_MSForEachDB 'USE [?];                               INSERT INTO #TempUsage SELECT TOP 20     DB_NAME() AS DatabaseName     , SCHEMA_NAME(o.Schema_ID) AS SchemaName     , OBJECT_NAME(s.[object_id]) AS TableName     , i.name AS IndexName     , (s.user_seeks + s.user_scans + s.user_lookups) AS [Usage]     , s.user_updates     , i.fill_factor FROM   sys.dm_db_index_usage_stats s INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id]             AND s.index_id = i.index_id INNER JOIN sys.objects o ON i.object_id = O.object_id   WHERE s.database_id = DB_ID()     AND i.name IS NOT NULL     AND OBJECTPROPERTY(s.[object_id], ''IsMsShipped'') = 0 ORDER BY [Usage] DESC'                                   SELECT TOP 20 * FROM #TempUsage ORDER BY [Usage] DESC DROP TABLE #TempUsage

--碎片最多的索引，这类索引应该rebuild，否则会严重拖累数据库的性能
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED SELECT                                                         DB_NAME() AS DatbaseName     , SCHEMA_NAME(o.Schema_ID) AS SchemaName     , OBJECT_NAME(s.[object_id]) AS TableName     , i.name AS IndexName     , ROUND(s.avg_fragmentation_in_percent,2) AS [Fragmentation %] INTO #TempFragmentation FROM sys.dm_db_index_physical_stats(db_id(),null, null, null, null) s INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id]     AND s.index_id = i.index_id INNER JOIN sys.objects o ON i.object_id = O.object_id   WHERE 1=2 EXEC sp_MSForEachDB 'USE [?];                               INSERT INTO #TempFragmentation SELECT TOP 20     DB_NAME() AS DatbaseName     , SCHEMA_NAME(o.Schema_ID) AS SchemaName     , OBJECT_NAME(s.[object_id]) AS TableName     , i.name AS IndexName     , ROUND(s.avg_fragmentation_in_percent,2) AS [Fragmentation %] FROM sys.dm_db_index_physical_stats(db_id(),null, null, null, null) s INNER JOIN sys.indexes i ON s.[object_id] = i.[object_id]     AND s.index_id = i.index_id INNER JOIN sys.objects o ON i.object_id = O.object_id   WHERE s.database_id = DB_ID()   AND i.name IS NOT NULL   AND OBJECTPROPERTY(s.[object_id], ''IsMsShipped'') = 0 ORDER BY [Fragmentation %] DESC'                         SELECT top 20 * FROM #TempFragmentation ORDER BY [Fragmentation %] DESC DROP TABLE #TempFragmentation


--自上次SQL Server重启后，找出完全没有使用的索引，这类索引应该小心对待，不能一概而论，要看是什么原因导致这种问题
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED SELECT                                                     DB_NAME() AS DatbaseName     , SCHEMA_NAME(O.Schema_ID) AS SchemaName     , OBJECT_NAME(I.object_id) AS TableName     , I.name AS IndexName INTO #TempNeverUsedIndexes FROM sys.indexes I INNER JOIN sys.objects O ON I.object_id = O.object_id WHERE 1=2 EXEC sp_MSForEachDB 'USE [?];                           INSERT INTO #TempNeverUsedIndexes SELECT     DB_NAME() AS DatbaseName     , SCHEMA_NAME(O.Schema_ID) AS SchemaName     , OBJECT_NAME(I.object_id) AS TableName     , I.NAME AS IndexName FROM sys.indexes I INNER JOIN sys.objects O ON I.object_id = O.object_id LEFT OUTER JOIN sys.dm_db_index_usage_stats S ON S.object_id = I.object_id         AND I.index_id = S.index_id         AND DATABASE_ID = DB_ID() WHERE OBJECTPROPERTY(O.object_id,''IsMsShipped'') = 0   AND I.name IS NOT NULL   AND S.object_id IS NULL' SELECT * FROM #TempNeverUsedIndexes                         ORDER BY DatbaseName, SchemaName, TableName, IndexName DROP TABLE #TempNeverUsedIndexes
  --查看索引统计的相关信息
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED SELECT     ss.name AS SchemaName     , st.name AS TableName     , s.name AS IndexName     , STATS_DATE(s.id,s.indid) AS 'Statistics Last Updated'     , s.rowcnt AS 'Row Count'     , s.rowmodctr AS 'Number Of Changes'     , CAST((CAST(s.rowmodctr AS DECIMAL(28,8))/CAST(s.rowcnt AS DECIMAL(28,2)) * 100.0)                              AS DECIMAL(28,2)) AS '% Rows Changed' FROM sys.sysindexes s INNER JOIN sys.tables st ON st.[object_id] = s.[id] INNER JOIN sys.schemas ss ON ss.[schema_id] = st.[schema_id] WHERE s.id > 100   AND s.indid > 0   AND s.rowcnt >= 500 ORDER BY SchemaName, TableName, IndexName /* 因为查询计划是根据统计信息来的，索引的选择同样取决于统计信息， 所以根据统计信息更新的多寡可以看出数据库的大体状况，20%的自动更新对于大表来说非常慢。 */

 --查询数据库缺失索引状况
 SELECT  avg_total_user_cost * avg_user_impact * ( user_scans + user_seeks ) AS PossibleImprovement ,           last_user_seek ,           last_user_scan ,           [statement] AS [Object] ,           'CREATE INDEX [IDX_' + CONVERT(VARCHAR(32), GS.group_handle) + '_'           + CONVERT(VARCHAR(32), D.index_handle) + '_'           + REPLACE(REPLACE(REPLACE([STATEMENT], ']', ''), '[', ''), '.', '')           + ']' + ' ON ' + [statement] + ' (' + ISNULL(equality_columns, '')           + CASE WHEN equality_columns IS NOT NULL                       AND inequality_columns IS NOT NULL THEN ','                  ELSE ''             END + ISNULL(inequality_columns, '') + ')' + ISNULL(' INCLUDE ('                                                                 + included_columns                                                                 + ')', '') AS Create_Index_Syntax   FROM    sys.dm_db_missing_index_groups AS G           INNER JOIN sys.dm_db_missing_index_group_stats AS GS ON G.index_group_handle = GS.group_handle           INNER JOIN sys.dm_db_missing_index_details AS D ON G.index_handle = D.index_handle   ORDER BY statement,PossibleImprovement desc
--索引碎片整理
1）删除索引并重建
2）使用 DROP_EXISTING 语句重建索引
3）使用 ALTER INDEX REBUILD 语句重建索引(avg_fragmentation_in_percent>30%)
4）使用 ALTER INDEX REORGANIZE 重新组织索引（5%<avg_fragmentation_in_percent<=30%)