Question

如何识别最耗资源的SQL

Answer 1

执行最慢的SQL语句

SELECT

(total_elapsed_time / execution_count)/1000 N'平均时间ms'

,total_elapsed_time/1000 N'总花费时间ms'

,total_worker_time/1000 N'所用的CPU总时间ms'

,total_physical_reads N'物理读取总次数'

,total_logical_reads/execution_count N'每次逻辑读次数'

,total_logical_reads N'逻辑读取总次数'

,total_logical_writes N'逻辑写入总次数'

,execution_count N'执行次数'

,SUBSTRING(st.text, (qs.statement_start_offset/2) + 1,

((CASE statement_end_offset

WHEN -1 THEN DATALENGTH(st.text)

ELSE qs.statement_end_offset END

- qs.statement_start_offset)/2) + 1) N'执行语句'

,creation_time N'语句编译时间'

,last_execution_time N'上次执行时间'

FROM

sys.dm_exec_query_stats AS qs CROSS APPLY
sys.dm_exec_sql_text(qs.sql_handle) st

WHERE

SUBSTRING(st.text, (qs.statement_start_offset/2) + 1,

((CASE statement_end_offset

WHEN -1 THEN DATALENGTH(st.text)

ELSE qs.statement_end_offset END

- qs.statement_start_offset)/2) + 1) not like '�tch%'

ORDER BY

total_elapsed_time / execution_count DESC;

--总耗CPU最多的前个SQL:
SELECT TOP
20

total_worker_time/1000 AS [总消耗CPU 时间(ms)],execution_count [运行次数],

qs.total_worker_time/qs.execution_count/1000 AS [平均消耗CPU 时间(ms)],

last_execution_time AS [最后一次执行时间],max_worker_time /1000 AS [最大执行时间(ms)],

SUBSTRING(qt.text,qs.statement_start_offset/2+1,
(CASE WHEN
qs.statement_end_offset = -1
THEN DATALENGTH(qt.text)
ELSE
qs.statement_end_offset END -qs.statement_start_offset)/2 + 1)
AS [使用CPU的语法], qt.text [完整语法],
qt.dbid, dbname=db_name(qt.dbid),

qt.objectid,object_name(qt.objectid,qt.dbid) ObjectName
FROM sys.dm_exec_query_stats qs
WITH(nolock)
CROSS apply
sys.dm_exec_sql_text(qs.sql_handle) AS qt
WHERE execution_count>1
ORDER BY total_worker_time DESC

--平均耗CPU最多的前个SQL:
SELECT TOP 20

total_worker_time/1000 AS [总消耗CPU 时间(ms)],execution_count [运行次数],

qs.total_worker_time/qs.execution_count/1000 AS [平均消耗CPU 时间(ms)],

last_execution_time AS [最后一次执行时间],min_worker_time /1000 AS [最小执行时间(ms)],

max_worker_time /1000 AS [最大执行时间(ms)],

SUBSTRING(qt.text,qs.statement_start_offset/2+1,
(CASE WHEN
qs.statement_end_offset = -1
THEN DATALENGTH(qt.text)
ELSE
qs.statement_end_offset END -qs.statement_start_offset)/2 + 1)
AS [使用CPU的语法], qt.text [完整语法],
qt.dbid, dbname=db_name(qt.dbid),

qt.objectid,object_name(qt.objectid,qt.dbid) ObjectName
FROM sys.dm_exec_query_stats qs
WITH(nolock)
CROSS apply
sys.dm_exec_sql_text(qs.sql_handle) AS qt
WHERE execution_count>1
ORDER BY
(qs.total_worker_time/qs.execution_count/1000) DESC

Answer 2

1，看执行计划里面的cost值，作为参考
2，看sql的执行时间。