Right, record keeping. But when it's not your data, things get complicated. Imagine trying to understand how another firm's data systems work. You can talk with managers, who know how the business uses data. But they have no clue how the data are stored or managed. And you can talk with IT people, who know how data are stored or managed. But they have no clue how the data are used.

And yes, speed. Aggregating hundreds of gigabytes was nontrivial to do quickly. I started with Access, and then learned to manage and use SQL Server. And eventually a multi-Xeon server with lots of RAM and SAS-attached storage.