Querying Data Warehouses - Data Warehouse Systems: Design and Implementation - page 224

6.6 Bibliographic Notes
MDX was first introduced in 1997 by Microsoft as part of the OLE DB for
OLAP specification. After the commercial release of Microsoft OLAP Services
in 1998 and Microsoft Analysis Services in 2005, MDX was adopted by the
wide range of OLAP vendors, both at the server and the client side. The latest
version of the OLE DB for OLAP specification was issued by Microsoft in
1999. In Analysis Services 2005, Microsoft added some MDX extensions like
subqueries. This newer variant of MDX is sometimes referred to as MDX
2005. There are many topics about MDX. A popular introductory one is
[ 227 ], although it is somehow outdated, and more advanced topics on MDX
are, for example, [ 163 , 189 , 197 ]. MDX is also covered, although succinctly, in
general topics covering OLAP tools, such as [ 71 , 79 , 182 ].
XML for Analysis (abbreviated as XMLA) is an industry standard for com-
municating among analytical systems. XMLA is an application programming
interface (API) based on SOAP (Simple Object Access Protocol) designed for
OLAP and data mining. XMLA is maintained by XMLA Council, which is
composed of many companies, with Microsoft, Hyperion, and SAS being the
ocial XMLA Council founder members. In this chapter, we did not cover
XMLA due to the fact that XMLA requests are typically generated by client
tools and OLAP servers to communicate between them. XMLA is covered,
for example, in the topics about OLAP tools mentioned above.
Data Mining Extensions (DMX) is a query language for data mining
models supported by Analysis Services. Like SQL, it supports a data
definition language (DDL), a data manipulation language (DML), and a
data query language. Whereas SQL statements operate on relational tables
and MDX on data cubes, DMX statements operate on data mining models.
DMX is used to create and train data mining models and to browse, manage,
and predict against them. We will study DMX together with a data mining
overview in Chap. 9 . This is why we did not cover DMX in this chapter.
Self-service business intelligence is an approach to data analytics that
enables business users to access and work with corporate information in order
to create personalized reports and analytical queries on their own, without
the involvement of IT specialists. In order to realize this vision, Microsoft
introduced the Business Intelligence Semantic Model (BISM), which we
introduced in Chap. 3 . The BISM supports two models, the traditional
multidimensional model and a new tabular model. The tabular model was
designed to be simpler and easier to understand by users familiar with Excel
and the relational data model. In addition, Microsoft has created a new query
language to query the BISM tabular model. This language, called DAX (Data
Analysis Expressions), is not a subset of MDX, but rather a new formula
language that is an extension of the formula language in Excel. The DAX
statements operate against an in-memory relational data store and are used
to create custom measures and calculated columns. In this chapter, we did not