（转）以备不时之需
最耗时的sql
declare @n int
set @n=500 ;
with cte1 as
(
select a.*,t.*
from sys.dm_exec_query_stats a
cross apply sys.dm_exec_sql_text(a.plan_handle) t
where t.dbid >= 5
)
select
t.dbid,db_name(t.dbid) as dbname,
a.total_worker_time,a.avg_time_ms,a.execution_count,a.cache_count,
replace(replace(t.text,CHAR(10),' '),CHAR(13),' ')
from
(
select top(@n)
plan_handle,
sum(total_worker_time) / 1000 as total_worker_time ,
sum(execution_count) as execution_count ,
count(1) as cache_count,
(sum(total_worker_time) / sum(execution_count) ) / 1000 as avg_time_ms
from cte1
group by plan_handle
order by avg_time_ms desc
) a
cross apply sys.dm_exec_sql_text(a.plan_handle) t
where avg_time_ms > 200
order by avg_time_ms desc
go
最频繁的sql
declare @n int
set @n=500 ;
with cte1 as
(
select a.*,t.*
from sys.dm_exec_query_stats a
cross apply sys.dm_exec_sql_text(a.plan_handle) t
where t.dbid >= 5
)
select
t.dbid,db_name(t.dbid) as dbname,
a.execution_count,a.total_worker_time,a.avg_time_ms,a.cache_count,
replace(replace(t.text,CHAR(10),' '),CHAR(13),' ')
from
(
select top(@n)
plan_handle,
sum(total_worker_time) / 1000 as total_worker_time ,
sum(execution_count) as execution_count ,
count(1) as cache_count,
(sum(total_worker_time) / sum(execution_count) ) / 1000 as avg_time_ms
from cte1
group by plan_handle
order by avg_time_ms desc
) a
cross apply sys.dm_exec_sql_text(a.plan_handle) t
order by execution_count desc
go
耗cpu的sql
declare @n int
set @n=500 ;
with cte1 as
(
select a.*,t.*
from sys.dm_exec_query_stats a
cross apply sys.dm_exec_sql_text(a.plan_handle) t
where t.dbid >= 5
)
select
t.dbid,db_name(t.dbid) as dbname,
a.total_logical_reads,a.avg_reads,a.total_logical_writes,a.avg_writes,a.execution_count,
a.total_worker_time,a.avg_time_ms,a.cache_count,
replace(replace(t.text,CHAR(10),' '),CHAR(13),' ')
from
(
select top(@n)
plan_handle,
sum(total_logical_reads) as total_logical_reads,
(sum(total_logical_reads) / sum(execution_count) ) as avg_reads,
sum(total_logical_writes) as total_logical_writes,
(sum(total_logical_writes) / sum(execution_count) ) as avg_writes,
sum(execution_count) as execution_count,
count(1) as cache_count,
sum(total_worker_time) as total_worker_time ,
(sum(total_worker_time) / sum(execution_count) ) / 1000 as avg_time_ms
from cte1
group by plan_handle
order by ( (sum(total_logical_reads) / sum(execution_count) ) + (sum(total_logical_writes) / sum(execution_count) ) ) desc
) a
cross apply sys.dm_exec_sql_text(a.plan_handle) t
order by (avg_reads + avg_writes) desc
go
当前数据库可能缺少的索引
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
当前数据库没用到的索引
select tb_name=object_name(a.object_id)
,idx_name=b.name
,last_user_update
,c.colid,c.keyno
,col_name=d.name
into #tmp
from sys.dm_db_index_usage_stats a left join sys.indexes b on a.object_id=b.object_id and a.index_id=b.index_id
left join sys.sysindexkeys c on c.id=a.object_id and c.indid=a.index_id
left join syscolumns d on d.id=c.id and d.colid=c.colid
where database_id=db_id()
and last_user_seek is null
and last_user_scan is null
and last_user_lookup is null
and last_user_update is not null
order by tb_name,idx_name,keyno
select tb_name,idx_name,last_user_update
,keywords= stuff(
(select ','+ col_name
FROM #tmp
where tb_name=a.tb_name and idx_name=a.idx_name
order by tb_name,idx_name,keyno
for xml path('') )
,1,1,'')
from #tmp a
group by tb_name,idx_name,last_user_update
drop table #tmp
go
当前数据库索引的使用率
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
当前数据库指定表的索引使用情况
declare @table as nvarchar(100)
set @table = 't_ire_candidate';
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
go
-- 查找阻塞
select
b.text, – sql执行计划
b.dbid,
db_name(b.dbid) as dbname,
a.session_id, – 执行会话id
a.blocking_session_id, – 引起阻塞的会话id
a.status,
a.command,
a.wait_time,
a.wait_type,
a.wait_resource,
a.total_elapsed_time
from sys.dm_exec_requests a
cross apply sys.dm_exec_sql_text(a.sql_handle) b
where session_id in
(
select distinct request_session_id from sys.dm_tran_locks
)
通过 a.blocking_session_id 查看引起阻塞的进程，text是对应的sql脚本