Comment by quink

> Sparse associative arrays are the default data structure, so it's very popular in, e.g., medical applications, where you would want to be able to store thousands of different things, but any given patient will only need a few of them.

Caché has really been moving away from that though... CacheStorage stores data in a big list in the *D globals.

I think the power in CacheStorage really comes from the indices and - very relevantly to the healthcare industry - all the relationships. They've got a very complex schema they need to support and Caché continues to be pretty good at that kind of thing - see the implicit joins in their SQL variety for example or Zen.