Let us begin with a positive assumption. Assume that your project team has successfully completed the development of the first data mart. Everything was done according to schedule. Your management is pleased that the team finished the project under budget and comfortably before the deadline. All the results proved out in comprehensive testing. Your data warehouse is ready to be deployed. This is the big day.

One of your prominent users is sitting at the workstation poised to compose and run the first query. Before he or she touches the keyboard, several important questions come to mind.

  • Are there any predefined queries I can look at?

  • What are the various elements of data in the warehouse?

  • Is there information about unit sales and unit costs by product?

  • How can I browse and see what is available?

  • From where did they get the data for the warehouse? From which source systems?

  • How did they merge the data from the telephone orders system and the mail orders system?

  • How old is the data in the warehouse?

  • When was the last time fresh data was brought in?

  • Are there any summaries by month and product?

These questions and several more like them are very valid and pertinent. What are the answers? Where are the answers? Can your user see the answers? How easy is it for the user to get to the answers?

Metadata in a data warehouse contains the answers to questions about the data in the data warehouse. You keep the answers in a place called the metadata repository. Even ...

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