Sql Server 索引使用情况及优化的相关Sql语句分享

--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 int 
select @dbid = db_id() 
SELECT o.name as tablename,s.* FROM sys.dm_db_index_physical_stats (@dbid, NULL, NULL, NULL, NULL) s,sys.objects o 
where avg_fragmentation_in_percent>25 and o.object_id =s.object_id 
order by avg_fragmentation_in_percent desc 
GO 
-- 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_compiles 
from sys.dm_db_missing_index_group_stats s 
,sys.dm_db_missing_index_groups g 
,sys.dm_db_missing_index_details d 
where s.group_handle = g.index_group_handle 
and d.index_handle = g.index_handle 
order by s.avg_user_impact desc 
go 
-- 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 frag 
INTO #work_to_do 
FROM 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 
SELECT 
object_name(object_id) as table_name, 
( 
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 stats 
WHERE 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 stats 
where object_id = object_id(@table) 
order by user_seeks, user_scans, user_lookups asc 
--End Index 分析优化的相关 Sql