Click here to monitor SSC
SQLServerCentral is supported by Redgate
 
Log in  ::  Register  ::  Not logged in
 
 
 

James Serra's Blog

James is a big data and data warehousing technology specialist at Microsoft. He is a thought leader in the use and application of Big Data technologies, including MPP solutions involving hybrid technologies of relational data, Hadoop, and private and public cloud. Previously he was an independent consultant working as a Data Warehouse/Business Intelligence architect and developer. He is a prior SQL Server MVP with over 30 years of IT experience. James is a popular blogger (JamesSerra.com) and speaker, having presented at dozens of PASS events including the PASS Business Analytics conference and the PASS Summit. He is the author of the book “Reporting with Microsoft SQL Server 2012”. He received a Bachelor of Science degree in Computer Engineering from the University of Nevada-Las Vegas.

Data Warehouse vs Data Mart

I see a lot of confusion on what exactly is the difference between a data warehouse and a data mart.  The best definition that I have heard of a data warehouse is:

“A relational database schema which stores historical data and metadata from an operational system or systems, in such a way as to facilitate the reporting and analysis of the data, aggregated to various levels”.

Or more simply:

“A single organizational repository of enterprise wide data across many or all subject areas”.

Typical data warehouses have these characteristics:

  • Holds multiple subject areas
  • Holds very detailed information
  • Works to integrate all data sources
  • Does not necessarily use a dimensional model but feeds dimensional models.

On the other hand, a data mart is the access layer of the data warehouse environment that is used to get data out to the users.  The data mart is a subset of the data warehouse which is usually oriented to a specific business line or team.

According to the Inmon school of data warehousing, a dependent data mart is a logical subset (view) or a physical subset (extract) of a larger data warehouse, usually isolated for the need to have a special data model or schema (e.g., to restructure for OLAP).  One of the benefits of the new Tabular mode in SSAS is that you can build that on top of a data warehouse instead of a data mart, saving time by not having to build a data mart.

So in short, I like to think of a data warehouse as containing many subject areas, and a data mart as containing just one of those subject areas.

More info:

Data Mart vs Data Warehouse – The Great Debate

Data Warehouse Architecture – Kimball and Inmon methodologies

Data Mart Does Not Equal Data Warehouse

Data mart or data warehouse?

Data Warehouse – Data Mart

Data Warehouse vs Data Mart

Comments

Leave a comment on the original post [www.jamesserra.com, opens in a new window]

Loading comments...