は、次の非常に複雑なクエリ

Question

を理解するのに役立つ必要があります。それは大きな助けになるでしょう。各部分が何をしているかのちょうど短いメモやポインタ..

SELECT qs.execution_count AS [Runs], 
        (qs.total_worker_time - qs.last_worker_time)/(qs.execution_count - 1) AS [Avg time], 
        qs.last_worker_time AS [Last time], 
        (qs.last_worker_time - ((qs.total_worker_time - qs.last_worker_time)/
        (qs.execution_count - 1))) AS [Time Deviation], 
        CASE WHEN qs.last_worker_time = 0 
          THEN 100 
          ELSE (qs.last_worker_time - ((qs.total_worker_time - 
           qs.last_worker_time)/(qs.execution_count - 1))) * 100 
        END 
        /(((qs.total_worker_time - qs.last_worker_time)/
         (qs.execution_count - 1.0))) AS [% Time Deviation], 
        qs.last_logical_reads + qs.last_logical_writes + qs.last_physical_reads AS [Last IO], 
        ((qs.total_logical_reads + qs.total_logical_writes + qs.total_physical_reads) - 
        (qs.last_logical_reads + last_logical_writes + qs.last_physical_reads))/
        (qs.execution_count - 1) AS [Avg IO], 
        SUBSTRING (qt.text,(qs.statement_start_offset/2) + 1, 
           ((CASE WHEN qs.statement_end_offset = -1 
           THEN LEN(CONVERT(NVARCHAR(MAX), qt.text)) * 2 
           ELSE qs.statement_end_offset 
           END - qs.statement_start_offset)/2) + 1) AS [Individual Query], 
        qt.text AS [Parent Query], 
        DB_NAME(qt.dbid) AS [DatabaseName] 
       INTO #SlowQueries 
       FROM sys.dm_exec_query_stats qs 
       CROSS APPLY sys.dm_exec_sql_text(qs.plan_handle) qt 
       WHERE qs.execution_count > 1 
       AND qs.total_worker_time != qs.last_worker_time 
       ORDER BY [% Time Deviation] DESC 

       SELECT [Runs], [Avg time], [Last time], [Time Deviation], [% Time Deviation], 
        [Last IO], [Avg IO], [Last IO] - [Avg IO] AS [IO Deviation], 
        CASE WHEN [Avg IO] = 0 
          THEN 0 
          ELSE ([Last IO]- [Avg IO]) * 100/[Avg IO] 
        END AS [% IO Deviation], 
        [Individual Query], [Parent Query], [DatabaseName] 
      INTO #SlowQueriesByIO 
      FROM #SlowQueries 
      ORDER BY [% Time Deviation] DESC 

      SELECT [Runs], [Avg time], [Last time], [Time Deviation], [% Time Deviation], [Last IO], 
        [Avg IO], [IO Deviation], [% IO Deviation], 
        [Impedance] = [% Time Deviation] - [% IO Deviation], [Individual Query], [Parent Query], 
        [DatabaseName] 
      FROM #SlowQueriesByIO 
      WHERE [% Time Deviation] - [% IO Deviation] > 20 
      ORDER BY [Impedance] DESC 
      DROP TABLE #SlowQueries 
      DROP TABLE #SlowQueriesByIO 

は、誰も私が上記のクエリを理解する助けてください。それは単に私が理解するにはあまりにも複雑すぎる。そのSQLサーバのDMVが見つかりました。

Answer 1

これがすべてを説明する：

http://www.sqlservercentral.com/articles/Performance+Tuning/63638/