What Is a Data Warehouse?

Technology types (the authors included) love to use opaque terms for pretty simple concepts. You may have heard of the term “data warehouse” or “data mart.” We will define them both in the context of reporting. Your IT people don’t like running reports directly against your HRIS and other production systems that lots of people need to use at the same time. Reports slow down systems. It’s also inefficient to run reports off these systems for a few technical reasons.

A data mart is a more compact version of a portion of the data in your HRIS, ATS, or other production system. The data mart is dedicated just to reporting. It has no other purpose. This takes the pressure off your live systems to satisfy your reporting needs and allow other users to do the work of HR (adding employees, employee self-service, and so on). Think of a data warehouse as a collection of data marts all working together. If you have data from 10 different systems and you want to report on all of them, likely your IT team will talk about building a data warehouse. Your organization may have data stored in a talent management system, HRIS, benefits system, or performance management system. Data warehouses need to be carefully planned, so the more you know about the metrics you need to report, the better, cheaper, and faster a data warehouse can be built and be useful to your organization.

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