Field note · July 9, 2023
Course note — Batch, streaming, and the honest difference
Streaming is not "batch but faster". It is a different consistency model with different failure modes, and most teams that adopt it did not need to.
Revised Batch, streaming, and the honest difference this week. The change was small and the reason was not.
Streaming is not "batch but faster". It is a different consistency model with different failure modes, and most teams that adopt it did not need to.
The first draft explained the mechanism and stopped. What was missing was the failure: the thing that happens when you get it wrong, described concretely enough that someone recognises it later. A lesson that only teaches the correct version leaves you unable to spot the incorrect one, which is the situation you will actually be in.
It sits in the Getting the data in module. The exercise is a thinking one rather than a query one — some of this material is about deciding what to compute, and that does not need a keyboard.
Ordering matters here more than in most courses. It follows What a pipeline is really doing and leads into Idempotency, backfills, and yesterday arriving twice, and reading it out of sequence mostly works but costs you the setup.
Free means free, and it also means we can rewrite it whenever it is wrong. No edition, no errata PDF, nothing to repurchase. The whole course is 36 lessons and the fixes land the day we find them.