操作系统是Windows2008R2 ,数据库是SQL2014 64位。
近阶段服务器出现过几次死机，管理员反馈机器内存使用率100%导致机器卡死。于是做了个监测服务器的软件实时记录CPU数据，几日观察得出数据如下：
SQL优化方法：
1、查看连接对象
USE master GO --如果要指定数据库就把注释去掉 SELECT * FROM sys.[sysprocesses] WHERE [spid]>50 --AND DB_NAME([dbid])=‘gposdb‘
当前连接对象有67个其中‘WINAME’的主机名，‘jTDS’的进程名不属于已知常用软件，找到这台主机并解决连接问题。在360流量防火墙中查看有哪个软件连接了服务器IP，除之。
2、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。
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](der.[sql_handle]) AS dest WHERE [session_id]>50 AND DB_NAME(der.[database_id])=‘gposdb‘ 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
--在SSMS里选择以文本格式显示结果 SELECT TOP 10 dest.[text] AS ‘sql语句‘ FROM sys.[dm_exec_requests] AS der CROSS APPLY sys.[dm_exec_sql_text](der.[sql_handle]) AS dest WHERE [session_id]>50 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
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](der.[sql_handle]) AS dest WHERE [session_id]>50 ORDER BY [cpu_time] DESC
4、查询CPU占用最高的SQL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
5、索引缺失查询
SELECT
DatabaseName = DB_NAME(database_id)
,[Number Indexes Missing] = count(*)
FROM sys.dm_db_missing_index_details
GROUP BY DB_NAME(database_id)
ORDER BY 2 DESC;
SELECT TOP 10
[Total Cost] = ROUND(avg_total_user_cost * avg_user_impact * (user_seeks + user_scans),0)
, avg_user_impact
, TableName = statement
, [EqualityUsage] = equality_columns
, [InequalityUsage] = inequality_columns
, [Include Cloumns] = included_columns
FROM sys.dm_db_missing_index_groups g
INNER JOIN sys.dm_db_missing_index_group_stats s
ON s.group_handle = g.index_group_handle
INNER JOIN sys.dm_db_missing_index_details d
ON d.index_handle = g.index_handle
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。