Posts tagged "interviews"

Two requests read the same row, both change it, and the second save quietly erases the first. A version number turns that silent bug into a conflict you can catch. Here is how optimistic locking works.

When two systems edit the same record, last-write-wins is the easy answer. It also throws away data on purpose. Here is when that is fine, and when it is a trap.

Offset pagination is easy to write and breaks in two ways: it gets slow, and it skips or repeats rows when the data changes. Cursor pagination fixes both. Here is the difference.

Everybody wants exactly-once delivery. Over a network it is impossible. Here is why, and the trick that gives you the same result in practice.

A tutor-style walkthrough of what a distributed database control plane actually is, why metadata is the crown jewel, where Raft fits in, and how to follow one request end-to-end to remember the whole design.