Sql Server 索引使用情况及优化的相关 Sql

Sql Server 索引使用情况及优化的相关 Sql 语句，非常好的SQL语句，记录于此：

 

--Begin Index(索引) 分析优化的相关 Sql -- 返回当前数据库所有碎片率大于25%的索引-- 运行本语句会扫描很多数据页面-- 避免在系统负载比较高时运行-- 避免在系统负载比较高时运行declare @dbid intselect @dbid = db_id()SELECT o.name as tablename,s.* FROM sys.dm_db_index_physical_stats (@dbid, NULL, NULL, NULL, NULL) s,sys.objects owhere avg_fragmentation_in_percent>25 and o.object_id =s.object_idorder by avg_fragmentation_in_percent descGO-- 当前数据库可能缺少的索引-- 非常好用的 Sql 语句select d.*        , s.avg_total_user_cost        , s.avg_user_impact        , s.last_user_seek        ,s.unique_compilesfrom sys.dm_db_missing_index_group_stats s        ,sys.dm_db_missing_index_groups g        ,sys.dm_db_missing_index_details dwhere s.group_handle = g.index_group_handleand d.index_handle = g.index_handleorder by s.avg_user_impact descgo-- 自动重建或重新组织索引-- 比较好用，慎用，特别是对于在线 DB-- Ensure a USE <databasename> statement has been executed first.SET NOCOUNT ON;DECLARE @objectid int;DECLARE @indexid int;DECLARE @partitioncount bigint;DECLARE @schemaname nvarchar(130); DECLARE @objectname nvarchar(130); DECLARE @indexname nvarchar(130); DECLARE @partitionnum bigint;DECLARE @partitions bigint;DECLARE @frag float;DECLARE @command nvarchar(4000); -- Conditionally select tables and indexes from the sys.dm_db_index_physical_stats function -- and convert object and index IDs to names.SELECT    object_id AS objectid,    index_id AS indexid,    partition_number AS partitionnum,    avg_fragmentation_in_percent AS fragINTO #work_to_doFROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, 'LIMITED')WHERE avg_fragmentation_in_percent > 10.0 AND index_id > 0;-- Declare the cursor for the list of partitions to be processed.DECLARE partitions CURSOR FOR SELECT * FROM #work_to_do;-- Open the cursor.OPEN partitions;-- Loop through the partitions.WHILE (1=1)    BEGIN;        FETCH NEXT           FROM partitions           INTO @objectid, @indexid, @partitionnum, @frag;        IF @@FETCH_STATUS < 0 BREAK;        SELECT @objectname = QUOTENAME(o.name), @schemaname = QUOTENAME(s.name)        FROM sys.objects AS o        JOIN sys.schemas as s ON s.schema_id = o.schema_id        WHERE o.object_id = @objectid;        SELECT @indexname = QUOTENAME(name)        FROM sys.indexes        WHERE  object_id = @objectid AND index_id = @indexid;        SELECT @partitioncount = count (*)        FROM sys.partitions        WHERE object_id = @objectid AND index_id = @indexid;-- 30 is an arbitrary decision point at which to switch between reorganizing and rebuilding.        IF @frag < 30.0            SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REORGANIZE';        IF @frag >= 30.0            SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REBUILD';        IF @partitioncount > 1            SET @command = @command + N' PARTITION=' + CAST(@partitionnum AS nvarchar(10));        EXEC (@command);        PRINT N'Executed: ' + @command;    END;-- Close and deallocate the cursor.CLOSE partitions;DEALLOCATE partitions;-- Drop the temporary table.DROP TABLE #work_to_do;GO-- 查看当前数据库索引的使用率-- 非常的有用SELECTobject_name(object_id) as table_name,(select namefrom sys.indexeswhere object_id = stats.object_id and index_id = stats.index_id) as index_name,*FROM sys.dm_db_index_usage_stats as statsWHERE database_id = DB_ID()order by table_name-- 指定表的索引使用情况declare @table as nvarchar(100)set @table = 't_name';SELECT(  select name  from sys.indexes  where object_id = stats.object_id and index_id = stats.index_id) as index_name,*FROM sys.dm_db_index_usage_stats as statswhere object_id = object_id(@table)order by user_seeks, user_scans, user_lookups asc--End Index 分析优化的相关 Sql