By: Siddharth Mehta
Overview
Data in Online Transaction Processing (OLTP) systems is suited to support convenient data storage for user-facing applications. The data model in such systems is highly normalized. For data warehousing environments, data is required to be in a schema that supports a dimensional model. Data is therefore transformed from the OLTP storage systems to a data warehouse using ETL, so that data can be aligned in a suitable format to create data marts from the data warehouse.
Two major theories driving the design of a data warehouse and data marts are from Ralph Kimball and Bill Inmon which are mostly practiced in real time environments. Generally data is gathered from OLTP systems and brought to the data warehouse. From the data warehouse, context / requirement specific data marts are created, which can be perceived as a subset of the data warehouse. Cube source data from these data marts, and client applications connect to the cube. The schema for a cube falls into two categories: Star and Snowflake. In simple terms, Star Schema can be considered a more denormalized form of schema compared to Snowflake.
Designing and developing a data warehouse is out scope for this tutorial. For the purpose of development, we will install and use the AdventureWorks DW database. We will then create a SSAS project and create a data source which will connect to this database. Finally we will create a star schema using a Data Source View.
