OLAP allows complex, multidimensional queries over large datasets to be rapidly answered. An OLAP system models the world as facts representing quantitative or qualitative measurements of things of interest. This article defines the different types and their pros and cons.
APIs and Query Languages
Unlike relational databases, which had SQL as the standard query language, and widespread APIs such as ODBC, JDBC and OLEDB, there was no such unification in the OLAP world for a long time. The first real standard API
was OLE DB for OLAP specification from Microsoft which appeared in 1997 and introduced the MDX query language. Several OLAP vendors – both server and client – adopted it. In 2001 Microsoft and Hyperion announced
the XML for Analysis specification, which was endorsed by most of the OLAP vendors. Since this also used MDX as a query language, MDX became the de facto standard. Since September-2011 LINQ can be used to query SSAS OLAP
cubes from Microsoft .NET.