caching – Page 3 – Türker Yıldırım

A transient that never expired because of one typo

NoteDecember 7, 20231 min read

A transient set with a mismatched key on read, so every request wrote a new row and none was ever read. A transient with an expiry is only…

The bundle we split by route, and the waterfall it created

Deep diveOctober 24, 202310 min read

A 900 KB bundle, split by route, and a page that got slower. Six sequential requests before the first render.

Redis 7.2, and the client-side caching I did not use

NoteSeptember 21, 20232 min read

Tracking mode lets Redis invalidate a client’s local cache, which is a genuinely good feature and is not free in PHP. The feature suits an application server with…

The N+1 that only appeared in production

Deep diveJuly 29, 202310 min read

An endpoint at 40 ms locally and 2.1 seconds in production. Nine hundred queries on one request, and three on the same request in a test.

Reading from a replica after a write, and the lie it tells

NoteJuly 18, 20232 min read

A form that saves and redirects to a page that reads, with a replica that is 200 ms behind and a redirect that takes 40. Sticky-per-request covers the…

A cold cache after every deploy, and the warmer we wrote

NoteJune 22, 20231 min read

A deploy that flushes the cache produces two minutes of every request doing the expensive thing at once. A warmer is an admission that the cache is load-bearing,…

A cache key with a version prefix, and the flush I stopped running

NoteMay 16, 20231 min read

A deploy that changed a serialised shape needed every cached entry invalidated, and the tool for that had been FLUSHDB. Flushing invalidates everything, including the ninety per cent…

Cache stampede, and a lock shorter than the work

NoteApril 27, 20232 min read

A cache entry expiring under load means every request recomputes it at once, and a lock that expires before the computation finishes makes it worse. Two things have…

A block that renders on the server and edits on the client

Deep diveMarch 17, 202310 min read

A block showing live stock levels, which cannot be saved into post content. Static markup that was wrong the moment it was written.

A read replica, and the six queries that could not use it

Deep diveMarch 16, 202314 min read

A primary at 80% CPU and reports running during the working day. Setting up the replica takes an afternoon; the consistency model takes a month.