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The cost of vary headers is usually not in hashing the keys but storing multiple entries per url in an arbitrarily large combination of headers. I can imagine c
by phanimahesh 3y ago
The cost of vary headers is usually not in hashing the keys but storing multiple entries per url in an arbitrarily large combination of headers. I can imagine cdns not wanting the hassle, though I don't live the outcome.
- zoogeny 3y agoIt's worth noting that the cost of storage wasn't the issue in this case. They already had a system that allowed you to determine which headers in the Vary list would be respected and so you could calculate a worst-case storage load. I mean, it definitely was an issue in general and we were careful about avoiding the same content being stored multiple times but it wasn't the reasoning they communicated behind the change in the anecdote I related. I think the best suggestion was in another thread by @johncolanduoni where he pointed out the difficulty of storing, distributing and retrieving the metadata per-resource that would be necessary for each PoP to correctly determine the Vary requirements at request time.
- naasking 3y agoI'm not sure that tracks. If those variants are used, then eliminating support for Vary means they'll just it with new endpoints that return the same thing, so total number of cache entries remain unchanged.