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SQL性能优化常用语句(摘录网上)

1.把trace文件导入到表中

SELECT IDENTITY(BIGINT, 1, 1) AS RowNumber,* into TableNameFROM fn_trace_gettable(trace.trc, default)

2.查询CPU开销大的语句

SELECT top 100    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,creation_time FROM sys.dm_exec_query_stats where creation_time > 2014-11-01and (total_worker_time/execution_count) > 146341ORDER BY [avg_cpu_cost] DESC

3.查询阻塞

SELECT a.* FROM sys.[sysprocesses] aWHERE a.[spid]>50 AND DB_NAME(a.[dbid])=DBName and a.spid <> @@SPID and a.blocked > 0

4.查询连接数

SELECT COUNT(*) FROM [sys].[dm_exec_sessions] WHERE [session_id]>50

 

SQL性能优化常用语句(摘录网上)