SQL SERVER查询性能消耗,降低CPU使用率的方法

一.查看当前的数据库用户连接有多少

USE master

GO
SELECT *
FROM sys.[sysprocesses]
WHERE [spid] > 50
AND DB_NAME([dbid])=‘gposdb’

SELECT COUNT(*)
FROM [sys].[dm_exec_sessions]
WHERE [session_id] > 5

二.选取前10个最耗CPU时间的会话

SELECT TOP 10
[session_id] ,
[request_id] ,
[start_time] AS ‘开始时间’ ,
[status] AS ‘状态’ ,
[command] AS ‘命令’ ,
dest.[text] AS ‘sql语句’ ,
DB_NAME([database_id]) AS ‘数据库名’ ,
[blocking_session_id] AS ‘正在阻塞其他会话的会话ID’ ,
[wait_type] AS ‘等待资源类型’ ,
[wait_time] AS ‘等待时间’ ,
[wait_resource] AS ‘等待的资源’ ,
[reads] AS ‘物理读次数’ ,
[writes] AS ‘写次数’ ,
[logical_reads] AS ‘逻辑读次数’ ,
[row_count] AS ‘返回结果行数’
FROM sys.[dm_exec_requests] AS der
CROSS APPLY sys.dm_exec_sql_text AS dest
WHERE [session_id] > 50
AND DB_NAME(der.[database_id]) = ‘gposdb’
ORDER BY [cpu_time] DESC

三.查询前10个最耗CPU时间的SQL语句

SELECT TOP 10
dest.[text] AS ‘sql语句’
FROM sys.[dm_exec_requests] AS der
CROSS APPLY sys.dm_exec_sql_text AS dest
WHERE [session_id] > 50
ORDER BY [cpu_time] DESC

四.查询会话中有多少个worker在等待

SELECT TOP 10
[session_id] ,
[request_id] ,
[start_time] AS ‘开始时间’ ,
[status] AS ‘状态’ ,
[command] AS ‘命令’ ,
dest.[text] AS ‘sql语句’ ,
DB_NAME([database_id]) AS ‘数据库名’ ,
[blocking_session_id] AS ‘正在阻塞其他会话的会话ID’ ,
der.[wait_type] AS ‘等待资源类型’ ,
[wait_time] AS ‘等待时间’ ,
[wait_resource] AS ‘等待的资源’ ,
[dows].[waiting_tasks_count] AS ‘当前正在进行等待的任务数’ ,
[reads] AS ‘物理读次数’ ,
[writes] AS ‘写次数’ ,
[logical_reads] AS ‘逻辑读次数’ ,
[row_count] AS ‘返回结果行数’
FROM sys.[dm_exec_requests] AS der
INNER JOIN [sys].[dm_os_wait_stats] AS dows ON der.[wait_type] = [dows].[wait_type]
CROSS APPLY sys.dm_exec_sql_text AS dest
WHERE [session_id] > 50
ORDER BY [cpu_time] DESC

五.查询CPU占用高的语句

SELECT TOP 10
total_worker_time / execution_count AS avg_cpu_cost ,
plan_handle ,
execution_count ,
( SELECT SUBSTRING(text, statement_start_offset / 2 + 1,
( CASE WHEN statement_end_offset = -1
THEN LEN(CONVERT(NVARCHAR(MAX), text))

• 2
  ELSE statement_end_offset
  END - statement_start_offset ) / 2)
  FROM sys.dm_exec_sql_text(sql_handle)
  ) AS query_text
  FROM sys.dm_exec_query_stats
  ORDER BY [avg_cpu_cost] DESC

查询一下都是那些sql造成的大量的cpu资源,去优化sql