Sometimes people host software on a server they own or rent, the server is plenty fast, and it costs literally nothing to issue those queries at the scale on which they’re needed.
I see people downvoting this. Anyone who disagrees with this, we have YAGNI for a reason - if someone said to me my performance was fine and they added caches, I would look at them with a big hairy eyeball because we already know cache invalidation is a PITA, that correctness issues are easy to create, and now you have the performance of two different systems to manage.
Amazon actually moved away from caches for some parts of its system because consistent behavior is a feature, because what happens if your cache has problems and the interaction between that and your normal thing is slow? What if your cache has some bugs or edge case behavior? If you don't need it you are just doing a bunch of extra work to make sure things are in sync.
> "If we don't need performance, we don't need caches" feels like a great broader takeaway here.
I don't think this holds true. Caches are used for reasons other than performance. For example, caches are used in some scenarios for stampede protection to mitigate DoS attacks.
Also, the impact of caches on performance is sometimes negative. With distributed caching, each match and put require a network request. Even when those calls don't leave a data center, they do cost far more than just reading a variable from memory. I already had the displeasure of stumbling upon a few scenarios where cache was prescribed in a cargo cult way and without any data backing up the assertion, and when we took a look at traces it was evident that the bottleneck was actually the cache itself.
IanCal|5 months ago
indymike|5 months ago
amluto|5 months ago
hobs|5 months ago
Amazon actually moved away from caches for some parts of its system because consistent behavior is a feature, because what happens if your cache has problems and the interaction between that and your normal thing is slow? What if your cache has some bugs or edge case behavior? If you don't need it you are just doing a bunch of extra work to make sure things are in sync.
motorest|5 months ago
I don't think this holds true. Caches are used for reasons other than performance. For example, caches are used in some scenarios for stampede protection to mitigate DoS attacks.
Also, the impact of caches on performance is sometimes negative. With distributed caching, each match and put require a network request. Even when those calls don't leave a data center, they do cost far more than just reading a variable from memory. I already had the displeasure of stumbling upon a few scenarios where cache was prescribed in a cargo cult way and without any data backing up the assertion, and when we took a look at traces it was evident that the bottleneck was actually the cache itself.
ralegh|5 months ago