SQL Server 索引优化相关语句

--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@dbidint
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>25and o.object_id=s.object_id
orderby 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
orderby 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@objectidint;
DECLARE@indexidint;
DECLARE@partitioncountbigint;
DECLARE@schemanamenvarchar(130);
DECLARE@objectnamenvarchar(130);
DECLARE@indexnamenvarchar(130);
DECLARE@partitionnumbigint;
DECLARE@partitionsbigint;
DECLARE@fragfloat;
DECLARE@commandnvarchar(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_idAS 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 >10.0AND index_id >0;
-- Declare the cursor for the list of partitions to be processed.
DECLARE partitions CURSORFORSELECT*FROM #work_to_do;
-- Open the cursor.
OPEN partitions;
-- Loop through the partitions.
WHILE (1=1)
 BEGIN;
 FETCHNEXT
 FROM partitions
 INTO@objectid, @indexid, @partitionnum, @frag;
 IF@@FETCH_STATUS<0BREAK;
 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
 WHEREobject_id=@objectidAND index_id =@indexid;
 SELECT@partitioncount=count (*)
 FROM sys.partitions
 WHEREobject_id=@objectidAND 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(@partitionnumASnvarchar(10));
 EXEC (@command);
 PRINT N'Executed: '+@command;
 END;
-- Close and deallocate the cursor.
CLOSE partitions;
DEALLOCATE partitions;
-- Drop the temporary table.
DROPTABLE #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
whereobject_id= stats.object_idand index_id = stats.index_id
) as index_name,
*
FROM sys.dm_db_index_usage_stats as stats
WHERE database_id =DB_ID()
orderby table_name
-- 指定表的索引使用情况
declare@tableasnvarchar(100)
set@table='t_name';
SELECT
(
 select name
 from sys.indexes
 whereobject_id= stats.object_idand index_id = stats.index_id
) as index_name,
*
FROM sys.dm_db_index_usage_stats as stats
whereobject_id=object_id(@table)
orderby user_seeks, user_scans, user_lookups asc
--End Index 分析优化的相关 Sql