SQLSERVER优化（仅供自己学习记忆，不喜勿喷）

最新推荐文章于 2025-06-25 12:34:25 发布

转载最新推荐文章于 2025-06-25 12:34:25 发布 · 266 阅读

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CC 4.0 BY-SA版权

原文链接：https://www.cnblogs.com/vice/p/9163241.html

文章标签：

#sqlserver

本文介绍了用于检查SQL Server性能的查询，包括检测阻塞、CPU占用和索引缺失情况。通过执行提供的SQL语句，可以找出占用资源较高的SQL语句，等待资源的任务以及可能存在的索引问题，从而进行性能调优。

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

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

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

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;