Sql Server 索引使用情况及优化的相关Sql语句分享

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

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