SQL SERVER占用CPU过高优化S

然后使用下面语句看一下各项指标是否正常，是否有阻塞，正常情况下搜索结果应该为空。

1 SELECT TOP 10  2 [session_id],  3 [request_id],  4 [start_time] AS '开始时间',  5 [status] AS '状态',  6 [command] AS '命令',  7 dest.[text] AS 'sql语句',   8 DB_NAME([database_id]) AS '数据库名',  9 [blocking_session_id] AS '正在阻塞其他会话的会话ID', 10 [wait_type] AS '等待资源类型', 11 [wait_time] AS '等待时间', 12 [wait_resource] AS '等待的资源', 13 [reads] AS '物理读次数', 14 [writes] AS '写次数', 15 [logical_reads] AS '逻辑读次数', 16 [row_count] AS '返回结果行数' 17 FROM sys.[dm_exec_requests] AS der  18 CROSS APPLY  19 sys.[dm_exec_sql_text](der.[sql_handle]) AS dest  20 WHERE [session_id]>50 AND DB_NAME(der.[database_id])='gposdb'   21 ORDER BY [cpu_time] DESC

查看是哪些SQL语句占用较大可以使用下面代码

1 --在SSMS里选择以文本格式显示结果 2 SELECT TOP 10  3 dest.[text] AS 'sql语句' 4 FROM sys.[dm_exec_requests] AS der  5 CROSS APPLY  6 sys.[dm_exec_sql_text](der.[sql_handle]) AS dest  7 WHERE [session_id]>50   8 ORDER BY [cpu_time] DESC

3、如果SQLSERVER存在要等待的资源，那么执行下面语句就会显示出会话中有多少个worker在等待

1 SELECT TOP 10  2  [session_id],  3  [request_id],  4  [start_time] AS '开始时间',  5  [status] AS '状态',  6  [command] AS '命令',  7  dest.[text] AS 'sql语句',   8  DB_NAME([database_id]) AS '数据库名',  9  [blocking_session_id] AS '正在阻塞其他会话的会话ID', 10  der.[wait_type] AS '等待资源类型', 11  [wait_time] AS '等待时间', 12  [wait_resource] AS '等待的资源', 13  [dows].[waiting_tasks_count] AS '当前正在进行等待的任务数', 14  [reads] AS '物理读次数', 15  [writes] AS '写次数', 16  [logical_reads] AS '逻辑读次数', 17  [row_count] AS '返回结果行数' 18  FROM sys.[dm_exec_requests] AS der  19  INNER JOIN [sys].[dm_os_wait_stats] AS dows  20  ON der.[wait_type]=[dows].[wait_type] 21  CROSS APPLY  22  sys.[dm_exec_sql_text](der.[sql_handle]) AS dest  23  WHERE [session_id]>50   24  ORDER BY [cpu_time] DESC

4、查询CPU占用最高的SQL语句

1 SELECT TOP 10  2    total_worker_time/execution_count AS avg_cpu_cost, plan_handle,  3    execution_count,  4    (SELECT SUBSTRING(text, statement_start_offset/2 + 1,  5       (CASE WHEN statement_end_offset = -1  6          THEN LEN(CONVERT(nvarchar(max), text)) * 2  7          ELSE statement_end_offset  8       END - statement_start_offset)/2)  9    FROM sys.dm_exec_sql_text(sql_handle)) AS query_text 10 FROM sys.dm_exec_query_stats 11 ORDER BY [avg_cpu_cost] DESC

5、索引缺失查询

1 SELECT   2     DatabaseName = DB_NAME(database_id)  3     ,[Number Indexes Missing] = count(*)   4 FROM sys.dm_db_missing_index_details  5 GROUP BY DB_NAME(database_id)  6 ORDER BY 2 DESC;  7 SELECT  TOP 10   8         [Total Cost]  = ROUND(avg_total_user_cost * avg_user_impact * (user_seeks + user_scans),0)   9         , avg_user_impact 10         , TableName = statement 11         , [EqualityUsage] = equality_columns  12         , [InequalityUsage] = inequality_columns 13         , [Include Cloumns] = included_columns 14 FROM        sys.dm_db_missing_index_groups g  15 INNER JOIN    sys.dm_db_missing_index_group_stats s  16        ON s.group_handle = g.index_group_handle  17 INNER JOIN    sys.dm_db_missing_index_details d  18        ON d.index_handle = g.index_handle 19 ORDER BY [Total Cost] DESC;

找到索引缺失的表，根据查询结果中的关键次逐一建立索引。

做完这些测试，基本能找到问题。