Chapter 5. Historical Data

Building an effective real-time data processing and analytics platform requires that you first process and analyze your historical data. Ultimately, your goal should be to build a system that integrates real-time and historical data and makes both available for analytics. This is not the same as saying you should have only a single, monolithic datastore—for a sufficiently simple application, this might be possible, but not in general. Rather, your goal should be to provide an interface that makes both real-time and historical data accessible to applications and data scientists.

In a strict philosophical sense, all of your business’s data is historical data; it represents events that happened in the past. In the context of your business operations, “real-time data” refers to the data that is sufficiently recent to where its insights can inform time-sensitive decisions. The time window that encompasses “sufficiently recent” varies across industries and applications. In digital advertising and ecommerce, the real-time window is determined by the time it takes the browser to load a web page, which is on the order of milliseconds up to around a second. Other applications, especially those monitoring physical systems such as natural resource extraction or shipping networks, can have larger real-time windows, possibly in the ballpark of seconds, minutes, or longer.

Business Intelligence on Historical Data

Business intelligence (BI) traditionally refers to ...

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