Question

我在下面有一个MDX查询。这个查询有效，问题是它很慢，需要＆gt;即使数据集不是很大，也会返回15秒的结果。我认为查询应该在2秒内执行（它也用在登陆页面上，等待时间很麻烦）。由于所有IF THEN ELSE逻辑，[测量]。[星级]导致速度减慢。所有这一切都基于[平均分数]，它根据查找表中的范围从查找表中找到[星级]。对于例如如果[平均分数]＆lt; 86，[星级] = 1 如果[平均分数]＆gt; = 86且＆lt; = 90，[星级] = 2

[平均分数]是一个简单的和/计算。它可以根据用作参数的日期范围进行更改。您能否建议在下面的现有查询中进行优化，或者推荐另一种方法来计算[星级]？

MDX查询如下：

    WITH 
       MEMBER [Measures].[MeanScore] AS ([Measures].[Standard Point Assignment - Sum]/[Measures].[Episode Of Care HCAHPS Count])
       MEMBER [Measures].[StarRating] AS 
       CASE 
       WHEN [HCAHPS Star Rating].[HCAHPS Star Rating ID].CurrentMember IS [HCAHPS Star Rating].[HCAHPS Star Rating ID].[All] 
          THEN 
         CASE 
           WHEN [Measures].[HSR-HCHCAHPS Domain ID] = TAIL([HCAHPS Star Rating].[HCAHPS Star Rating ID].[HCAHPS Star Rating ID]).Item(0).Item(0).Properties('HCHCAHPS Domain ID') 
                  THEN 
               (
                [Measures].[Rating], 
                Tail([HCAHPS Star Rating].[HCAHPS Star Rating ID].[HCAHPS Star Rating ID]).Item(0).Item(0)
               )
           ELSE 
               (
                [Measures].[StarRating],
                Tail([HCAHPS Star Rating].[HCAHPS Star Rating ID].[HCAHPS Star Rating ID]).Item(0).Item(0).PrevMember
               )
         END 
       ELSE 
         CASE 
           WHEN [Measures].[MeanScore] > [HCAHPS Star Rating].[HCAHPS Star Rating ID].CurrentMember.Properties('Start', typed)
           AND [Measures].[HC-HCAHPS Domain ID] = [HCAHPS Star Rating].[HCAHPS Star Rating ID].CurrentMember.Properties('HCHCAHPS Domain ID', typed) 
                  THEN 
               (
               [Measures].[Rating], 
                [HCAHPS Star Rating].[HCAHPS Star Rating ID].CurrentMember
                )
           ELSE 
               (
                [Measures].[StarRating],
                [HCAHPS Star Rating].[HCAHPS Star Rating ID].CurrentMember.PrevMember
               ) 
         END 
     END 
SELECT 
    {
        [Measures].[Episode Of Care HCAHPS Count]
        ,[Measures].[Is Top Box]
        ,[Measures].[CompositeScore]   
        ,[Measures].[PromoterCount]
        ,[Measures].[PromoterPercent]
        ,[Measures].[PassiveCount]
        ,[Measures].[PassivePercent]
        ,[Measures].[DetractorCount]     
        ,[Measures].[DetractorPercent]
        ,[Measures].[StarRating]
        ,[Measures].[MeanScore]
    } ON COLUMNS, 
    NONEMPTYCROSSJOIN
    (
        {NONEMPTY([HCAHPS Domain].[HCAHPS Survey Methodology ID].[HCAHPS Survey Methodology ID])}
        ,DESCENDANTS(StrToSet('[Org Hierarchy].[Parent Key].&[118418]'))
        ,{[HCHCAHPS Domain].[HC Domain Group].[HC Domain Group]}
        ,{[HCHCAHPS Domain].[HCAHPS Domain Name].[HCAHPS Domain Name]}
        ,{[HCAHPS Question Answer].[Question Number].AllMembers}
     ) ON ROWS 
     FROM [CAHPS] 
     WHERE 
     (
        StrToMember("[Date].[Date].&[" + FORMAT(NOW()-365,"yyyy-MM-ddT00:00:00")  + "]",CONSTRAINED):StrToMember("[Date].[Date].&[" + FORMAT(NOW(),"yyyy-MM-ddT00:00:00")  + "]",CONSTRAINED)
     )

Answer 1

通常，Analysis Services MDX中的IIF和CASE语句可能会发现某些性能下降。虽然大多数IIF语句都是相对便宜，复杂的嵌套条件（包含大量IIF语句），但这会导致Analysis Services公式引擎最终逐个运行查询。

对于高性能查询，目标是使查询以子空间模式（或块计算）而不是逐个单元模式运行。要在IIF语句的上下文中执行此操作，请尝试使用SCOPE语句。将IIF语句转换为SCOPE的一个很好的参考是Mosha Pasumansky的博文是Performance of IIF function in MDX。

顺便提一下，有关子空间计算的更多信息（与逐个单元格相比），请参阅Analysis Services Performance Guide

的第3.2.1节

SSAS根据另一个计算的度量计算度量

1 个答案: