Set Functions: The .AllMembers Function - Page 2

December 7, 2007

Procedure: Use the .AllMembers Function to Filter a Dataset to Meet a Business Need

Having demonstrated the basic operation of .AllMembers, we are ready to address another requirement to which the client representatives have referred in earlier conversations. To detail the requirement, our colleagues have asked us to address a specific, immediate need, although they hope to be able to extrapolate the concepts we introduce to other, similar needs that continually arise within the organization. The authors / developers have asked that we construct a query that presents all measures (including calculated members / measures) for each of the Product Categories offered by the organization for their current and prior year (2004 and 2003, respectively), presented by Product Category, and subanalyzed by Customer Country. Our colleagues explain that management is attempting to perform analysis upon the Categories, specifically within the context of the “contribution” of each Customer Country toward the totals for each Category value. While management will likely prune the measures presented to a smaller subset going forward, the initial exercise will allow them to see all measures, including calculations, for the purpose of considering each for relevance, before deciding which to eliminate from prospective presentations. The client representatives assure us that, once they understand the concepts, they will seek to extend, or otherwise modify, and parameterize various parts of this (or a similar) query, within reports they will later create using Reporting Services, but that this example will suffice for now.

Because the initial business requirement entails working with all measures (“all members of the Measure dimension,” as it were), we explain that .AllMembers promises to be useful in generating the desired presentation. We confirm our understanding of the foregoing needs, as well as our conclusion that we have happened upon a great opportunity to both assist the client in meeting its immediate needs and to provide examples that leverage the MDX .AllMembers function. We set out to craft a query that relies upon .AllMembers, in conjunction with a couple of other the MDX functions, to meet the business need.

A new tab, with a connection to the Adventure Works cube (we can see it listed in the selector of the Metadata pane, once again) appears in the Query pane.

-- MDX061-2: Basic Use of .ALLMEMBERS Function;  Measure Dimension

SELECT

   CROSSJOIN(

      {[Measures].ALLMEMBERS},

         {[Date].[Calendar Year].[CY 2004]:[Date].[Calendar Year].[CY 2003]})

      ON AXIS (0),

   CROSSJOIN(

      {[Product].[Product Categories].CHILDREN},

         [Customer].[Country].[Country].MEMBERS

      ON AXIS (1)

FROM

               [Adventure Works]

The Query pane appears, with our input, as shown in Illustration 6.

The Results pane is, once again, populated by Analysis Services. This time, the dataset partially depicted in Illustration 7 appears.

In the returned dataset, we see the juxtaposed Years (2003 and 2004), which we generate via the MDX Range operator (“:”) and all measures within the cube – including calculated members / measures, which we deliver via the .AllMembers function. Moreover, we leverage the .Children and .Members functions to specify a row axis containing Product Categories, which we further subanalyze by Customer Country. We perform the desired juxtapositions within the query via the CrossJoin() function.

Of primary focus within our practice example is our use of the .AllMembers function, in conjunction with these other functions, to return all measures – in effect, “all members of the Measures dimension.” (We can easily verify operation by observing that all measures within the cube appear within the dataset – we can scroll over to see that all measures are present.) In this example, we can also see another characteristic of the behavior of .AllMembers in cases where a dimension contains only a single visible hierarchy: in such cases, the hierarchy can be referenced by the hierarchy name or the dimension name, because the dimension name in such a scenario is resolved to its only visible hierarchy. In our immediate example, Measures.AllMembers is a valid MDX expression because it resolves to the only hierarchy in the Measures dimension.

The client developers and report authors express satisfaction with the results, and confirm their understanding of the operation of the .AllMembers function within the context we have presented, among other uses we have discussed in earlier sections. We suggest to our client colleagues that, among numerous possibilities, the Years (“beginning” and “ending,” for that matter) might be parameterized, that we might build in the capability to swap crossjoined members, and that we might add other capabilities within the ultimate reporting dataset query. Suffice it to say that, assuming a thorough knowledge of the various layers of the Microsoft integrated BI solution, one can obtain many powerful capabilities and features, and knowing “where to put the intelligence” within the sometimes multiple choices can mean highly tuned performance and effective solutions for consumers throughout our organizations. For more of my observations on this subject see Multi-Layered Business Solutions ... Require Multi-Layered Architects.

Summary ...

In this article, we explored the MDX .AllMembers function, whose general purpose is to return a set composed of all members within a specified dimensional level or hierarchy. The set returned includes all calculated members contained within the specified level or hierarchy.

We examined the syntax involved with .AllMembers, and then undertook a couple of illustrative practice examples of uses for the function, generating queries that capitalized upon its capabilities. Throughout our practice session, we briefly discussed the results datasets we obtained from each of the queries we constructed, as well as extending our discussion to other possible options and uses for the concepts we exposed.

» See All Articles by Columnist William E. Pearson, III

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