Databases

Where an application's actual data lives — separate from the app's own container, since a database needs different backup, scaling, and durability handling than the stateless service sitting in front of it. Most self-hosted apps pick one for you; this is what to know when something actually asks you to choose.

OLTP — the normal one: an application's live state, optimised for lots of small reads and writes.

OLAP — analytics: aggregating huge numbers of rows at once, a different shape of problem entirely.