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It seems the article's implication is that they are relying on redis TTL and expiry to guarantee all keys exists or no keys exist, at all times, for a given key set.

I never got the impression that Redis gave guarantees on when expired keys were deleted, just that they would be eventually.

If the issue is that you want a consistent all or nothing, why not just use a single key to make that determination?

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we reordered our keys such that they can expire at different times - also redis checks a keys TTL before returning - and wont return if its expired. i think it will 'eventually' delete if its not accessed, but we only cared about keys being returned, not when its actually deleted

Thanks for clarifying. I wasn't aware of the fact that redis removes expired keys even if they aren't deleted. I've always thought of expiry as more of a resource management annotation. Interesting way to use it.

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