Namespace your cache keys so two different lookups never collide

Two completely different lookups end up sharing the exact same cache key, and one silently overwrites the other.

Beginner to intermediateRead 5 minDoing: about an hour6 steps

▶ Start

What you'll have at the end

A colon-separated cache key scheme where two different lookups never read each other's data

Before you start

You need

An app that already reads and writes more than one kind of lookup through the same cache (Redis or an equivalent key-value store), with at least one of those lookups keyed by nothing but a raw id or value.

Not covered

Deciding when a cache entry should expire or be deleted once its underlying data changes, and enforcing a maximum key length for very large caches; this only covers naming keys so two different lookups can never share one.

Leans on

6 steps

Where to go next

Fix a cache that shows old data

once every lookup has its own namespaced key, keeping that key's value fresh after a write is the separate problem covered there.

Checked 19 Aug 2026

Part of the Backend Caching cookbook