aso mdx

ASO: Understanding MDX Gary Crisci, Oracle Ace

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What is MDX?

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• MDX stands for Multi-Dimensional Expression •

MDX is a language that allows you to query OLAP cubes in a way reminiscent of that in which SQL allows you to query relational databases. –

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Fast Track to MDX, 2004, Whitehorn, Zare, Pasumansky

Unlike some other OLAP languages, it is not a full report-formatting language. The results of an MDX query come back to a client program as data structures that must be processed in some way to look like a spreadsheet, a chart, or some other form of output. This is quite similar to how SQL works with relational databases and how its related application programming interfaces (APIs) behave. –

MDX Solutions With Microsoft SQL Server Analysis Server 2005 and Hyperion Essbase Second Edition, 2006, Spofford, Harinath, Webb, Huang, Civardi

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How do we use MDX with Essbase? • There are two primary ways, at this time, to utilize MDX with Essbase. – Query data from an Essbase database • Aggregate Storage or Block Storage!

– Construct member formulas • Aggregate Storage only

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SQL SELECT Product, Sales, Margin FROM dbo.Transactions WHERE Year = ‘Jan’

MDX SELECT {[Measures].[Sales], [Measures].[Margin]} ON COLUMNS, {[Product].levels(0).members} ON ROWS FROM [SAMPASO].[BASIC] Must Define axis WHERE [Year].[Jan] specification to render multi-dimensional in a report. www.odtug.com

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Nesting rows using AXIS SELECT {[Measures].[Sales], [Measures].[Margin]} ON AXIS(0), {[Product].levels(0).members} ON AXIS(1), {[Scenario].children} ON AXIS(2) FROM [SAMPASO].[BASIC] WHERE [Year].[Jan]

Nesting columns is a little different SELECT {CrossJoin({[Measures].[Sales], [Measures].[Margin]}, {[Scenario].children})} ON axis(0), {[Product].levels(0).members} ON axis(1) FROM [SAMPASO].[BASIC] WHERE [Year].[Jan]

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• Naming Conventions – The most obvious way to identify a member is to start with the name of the dimension and work downwards, specifying the members at each level in the hierarchy until we reach the required members - Fast Track to MDX, 2004, Whitehorn, Zare, Pasumansky • [Jan] This works • [Year].[Jan] This is better • [Year].[Qtr1].[Jan] This is best practice – * No difference in performance – * Particularly important with Duplicate Member names – * No quotes - “Jan” vs. [Jan]

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• Tuples – A tuple is defined as an intersection of exactly a single member from each dimension in the cube. For each dimension that is not explicitly referenced, the current member is implicitly added to the tuple definition. A tuple always identifies (or has the potential to identify) a single cell in the multi-dimensional matrix. That could be an aggregate or a leaf level cell, but nevertheless one cell and only one cell is ever implied by a tuple. - Fast Track to MDX, 2004, Whitehorn, Zare, Pasumansky • ([Year].[Jan], [Measures].[Sales], [Product].[Cola], [Market].[East]) • ([Year].[Jan], [Measures].[Sales]) • ([Year].[Jan]) – * Wrap tuples in parenthesis ( ) – * Similar to a cross-dimensional operator • (“Jan”->”Sales”) vs. ([Year].[Jan], [Measures].[Sales])

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• Sets – A set is a collection of tuples with the same dimensionality. It may have more than one tuple, but it can also have only one tuple, or even have zero tuples, in which case it is an empty set. - Fast Track to MDX, 2004, Whitehorn, Zare, Pasumansky • {([Scenario].[Actual],[Measures].[Sales]), ([Scenario].[Actual],[Measures].[Margin])} • {[Year].levels(0).members} • {[Measures].[Sales]} – Wrap sets in { }

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• MDX Expressions WITH MEMBER [Measures].[Margin%] AS '[Measures].[Margin] / [Measures].[Sales]' SELECT {[Measures].[Sales], [Measures].[Margin], [Measures].[Margin%]} ON COLUMNS, {[Year].[Jan]} ON ROWS FROM [SAMPASO].[BASIC]

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This is IT

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This is Essbase

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• We use MDX Expressions to define member formulas in the Essbase outline • Same concept as member formulas in BSO • Many functions can be translated from Essbase calc language to MDX – In EAS go to Help -> Information Map -> Technical Reference – Go to MDX -> Aggregate Storage Topics -> MDX Outline Formulas • For version 7X go to MAXL -> MDX

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@AVG – Calculator: @AVG(SKIPMISSING, @CHILDREN(East)); – MDX: Avg([East].Children) • For SKIPNONE - Avg([East].Children,IncludeEmpty)

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@CHILDREN – Calculator: @CHILDREN(Market); – MDX: Children([Market]) OR [Market].Children @ICHILDREN – Calculator: @ICHILDREN(Market); – MDX: Union({[Market]},{[Market].children}) @CURRMBR – Calculator: @CURRMBR(Product); – MDX: CurrentMember([Product]) or [Product].CurrentMember @LEVMBRS – Calculator: @LEVMBRS(Product,0); – MDX: [Product].levels(0).Members www.odtug.com

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@LSIBLINGS – Calculator: @LSIBLINGS(Qtr4); – MDX: MemberRange([Qtr4].FirstSibling, [Qtr4].Lag(1)) @RSIBLINGS – Calculator: @RSIBLINGS(Qtr1); – MDX: MemberRange([Qtr1].Lead(1), [Qtr1].LastSibling) @PARENTVAL – Calculator: @PARENTVAL(Market, Sales); – MDX: ([Sales], [Market].CurrentMember.Parent).Value @REMOVE – Calculator: @REMOVE(@CHILDREN(East),@LIST(“New York”,Connecticut)); – MDX: Except({[East].Children}, {[New York], [Connecticut]}) @COUNT – Calculator: @COUNT(SKIPMISSING, @RANGE(Sales, Children(Product)); – MDX:NonEmptyCount(CrossJoin({[Sales]},{[Product].Children})) • For SKIPNONE – Count([Product].Children) www.odtug.com

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@IDESCENDANTS – Calculator: @IDESCENDANTS(Market); – MDX: Descendants([Market]) @DESCENDANTS – Calculator: @DESCENDANTS(Market,0); – MDX: Descendants([Market], [Market].levels(0)) OR • Leaves([Market]) –New in Sys 9

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@ISICHILD – Calculator: @ISICHILD(South); – MDX: IIF(Is([Market].CurrentMember,[South]) OR IsChild([Market].CurrentMember,[South]), ,)

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• Time Functionality – Leverage Analytic Dimensions

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• Period To Date Functions [QTD] = SUM( PeriodsToDate( [Year].Generations(2), [Year].CurrentMember ), [View].[Per] ) [YTD] = SUM( PeriodsToDate( [Year].Generations(1), [Year].CurrentMember ), [View].[Per] )

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• Time Balancing CASE WHEN IsUDA([Measures].CurrentMember, "TB_Last") THEN IIF(IsLeaf([Year].CurrentMember), [View].[Per], (ClosingPeriod ([Year].Levels(0), [Year].CurrentMember), [View].[Per]) ELSE [View].[Per] END Before

After

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• Time Balance – Skip Missing Problem

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Solution CASE WHEN IsUDA([Measures].CurrentMember,"TB_Last") THEN IIF(IsLeaf([Year].CurrentMember) AND Not IsEmpty([Year].CurrentMember),[View].[Per], IIF(IsLeaf([Year].CurrentMember), IIF (NonEmptyCount (MemberRange(Head([Year].levels(0).members ).item(0).item(0), [Year].CurrentMember,LEVEL),[View].[Per])> 0, ([View].[Per],Tail(Filter(MemberRange( Head([Year].levels(0).members).item(0).item(0), [Year].CurrentMember, LEVEL), Not IsEmpty([View].[Per]))).Item(0).Item(0)), MISSING), IIF (NonEmptyCount(DESCENDANTS([Year].CurrentMember,10,LEAVES),[View].[Per]) > 0, ([View].[Per],Tail(Filter(DESCENDANTS([Year].CurrentMember,10,LEAVES), Not IsEmpty([View].[Per]))).Item(0).Item(0)), IIF (NonEmptyCount([Year].levels(0).members,[View].[Per]) > 0, ([View].[Per], Tail(Filter([Year].levels(0).members, Not IsEmpty([View].[Per]))).Item(0).Item(0)),MISSING)))) ELSE [View].[Per] END

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George Spofford Revised Solution CASE WHEN IsUDA([Measures].CurrentMember, "TB_Last") THEN IIF(IsLeaf([Year].CurrentMember) AND Not IsEmpty([Year].CurrentMember),[View].[Per], IIF(IsLeaf([Year].CurrentMember), ([View].[Per],Tail(Filter (PeriodsToDate([Year].Generations(1), [Year].CurrentMember,), Not IsEmpty([View].[Per]))).Item(0).Item(0)), IIF (Not IsEmpty([View].[Per]),([View].[Per], Tail(Filter(DESCENDANTS([Year].CurrentMember,Year.Levels(0)), Not IsEmpty([View].[Per]))).Item(0).Item(0)), ([View].[Per],Tail(Filter([Year].levels(0).members, Not IsEmpty([View].[Per]))).Item(0).Item(0))))) ELSE [View].[Per] END

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Revised Period to Date Solution CASE WHEN IsUDA([Measures].CurrentMember, "TB_Last") THEN IIF(IsLeaf([Year].CurrentMember) AND Not IsEmpty([Year].CurrentMember),[View].[Per], IIF(IsLeaf([Year].CurrentMember), ([View].[Per],Tail(Filter (PeriodsToDate([Year].Generations(1), [Year].CurrentMember), Not IsEmpty([View].[Per]))).Item(0).Item(0)), IIF (Not IsEmpty([View].[Per]),([View].[Per], Tail(Filter(DESCENDANTS([Year].CurrentMember,Year.Levels(0)), Not IsEmpty([View].[Per]))).Item(0).Item(0)), ([View].[Per],Tail(Filter([Year].levels(0).members, Not IsEmpty([View].[Per]))).Item(0).Item(0))))) ELSE SUM(PeriodsToDate([Year].Generations(1),[Year].CurrentMember),[View].[Per]) END

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• Formula Precedence (Solve Order) – The mechanism that standard MDX uses for dealing with dimensional formula precedence is called solve order. Every calculated member has an associated solve order number, which is an integer that says what the calculation priority of the member is. When calculated members overlap on a cell, the member with the highest solve order number “wins” and is used to calculate the cell. - MDX Solutions, 2006, Spofford, Harinath, Webb, Huang, Civardi

- Default value is 0, maximum value is 127 - Multiple members can have the same solve order

- Dimension solve order sets the default solve order for all members in the dimension, you can still edit individual member’s order if required - In addition to calculating the correct value, Solve Order can yield huge performance gains for calculated members

- Test, Test, Test!!! www.odtug.com

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• Recap – MDX is a powerful query language, similar to SQL, that is used with multi-dimensional databases. – MDX can be used to query both ASO and BSO Essbase cubes, although it is primarily used for member expressions in ASO models. – Most Essbase calculator functions can be converted to MDX expressions – refer to the technical document. – You can leverage MDX expression in ASO cubes to simulate Dynamic Time Series (Period To Date) and Time Balancing functionality. – Solve Order is extremely important, both for calculating accurate results and performance.

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Questions

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