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
1 USE master
2 GO
3 --如果要指定数据库就把注释去掉
4 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。
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。
