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I'm currently researching SQL Server 2008 as a business intelligence solution, and currently looking at Analysis Services (and I'm pretty new to business intelligence as a whole...)

I'm a bit confused by some of the terms in SSAS, particularly the conceptual differences between cubes and MS's Unified Dimensional Model.

I believe that a cube in SSAS is basically an OLAP cube -- dimensions, measures, something that sits between the underlying data source and a business user.

But then that's kind of what I understand UDM to be as well.

The docs for SQL Server 2005 seem to suggest as much:

"A cube is essentially synonymous with a Unified Dimensional Model (UDM)".

But then the SQL Server 2008 pages sort of suggest that UDM is a wrapper for both multidimensional data (cubes) and relational data:

"Use the Unified Dimensional Model to provide one consolidated business view for relational and multidimensional data that includes business entities, business logic, calculations, and metrics."

This blog post suggests similarly:

"UDM provides a single dimensional model for all OLAP analysis and relational reporting needs. So you can use either MDX or SQL"

Is UDM something that sits above cubes? Or are they the same thing? I presume I would develop cubes with the Cube Designer application; what would I develop a UDM with?

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传统的多维数据集基于单个度量值组（事实），具有星形或雪花结构中的相关维度。

UDM（统一数据模型）允许您通过使用参考维度和多对多维度在几乎任何底层 SQL 数据模型上创建多维结构。

请注意，仅仅因为您可以，并不意味着您应该将 AS 放在任何旧结构的顶部 - 它很可能会表现不佳。传统的星型模式是最快的。

它有时也被认为是指附加的 SSAS 功能，例如操作和 KPI。

于 2010-03-29T20:56:31.980 回答