复制代码 代码如下:

--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