SQL性能调优

Question

有什么方法可以在特定时间点找到长时间运行的查询吗？

Answer 1

这是一个查询，您可以用来查找正在运行的查询并消耗更多时间。

 SELECT TOP 10 SUBSTRING(qt.TEXT, (qs.statement_start_offset/2)+1,
    ((CASE qs.statement_end_offset
    WHEN -1 THEN DATALENGTH(qt.TEXT)
    ELSE qs.statement_end_offset
    END - qs.statement_start_offset)/2)+1),
    qs.execution_count,
    qs.total_logical_reads, qs.last_logical_reads,
    qs.total_logical_writes, qs.last_logical_writes,
    qs.total_worker_time,
    qs.last_worker_time,
    qs.total_elapsed_time/1000000 total_elapsed_time_in_S,
    qs.last_elapsed_time/1000000 last_elapsed_time_in_S,
    qs.last_execution_time,
    qp.query_plan
    FROM sys.dm_exec_query_stats qs
    CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt
    CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp
    ORDER BY qs.total_logical_reads DESC -- logical reads
    -- ORDER BY qs.total_logical_writes DESC -- logical writes
    -- ORDER BY qs.total_worker_time DESC -- CPU time

这将是查询结果：

也请参考以下链接： https://stackify.com/performance-tuning-in-sql-server-find-slow-queries/

Answer 2

对于MySQL或Maria DB。基本上，您可以使用此查询；

SELECT * FROM INFORMATION_SHEMA.PROCESSLIST WHERE time > ** choose time in seconds **