In This Chapter
Figuring out what data your data warehouse needs from outside your company
Looking into the quality of your external data
Fitting external data into your data warehouse
Keeping your external data up-to-date and in working order
Your data warehouse is most likely incomplete until it includes data that comes from sources outside your company. You might want to build a picture of sales activity across all your divisions for the past three years; but wouldn't you also like to include competitors' sales results so that your data warehouse users can see how your company is doing in comparison?
If you call a competitor's chief information officer to ask whether someone could send you a regular stream of data pulled from the company's sales applications or reports from the consolidated sales analysis data warehouse that the company has already built, you probably get a response similar to, "Are you crazy?" Fortunately, you can obtain much of this type of information from publicly available sources.
Simply ask yourself this question: Looking at the complete list from within your company of all data sources that will provide data to the warehouse, what else do you need that you don't already have on the list — and what can you not get somewhere else within the company to help make business decisions?
Here's a list you can use as a starting point:
Your competitors' ...