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Caching is an abstraction, not an optimization

(buttondown.com)
134 points samuel246 | 2 comments | 01 Jul 25 10:42 UTC | HN request time: 0.414s | source
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necovek ◴[03 Jul 25 19:22 UTC] No.44458350[source]▶
On top of the other things mentioned (caching always introduces complexity with lifetime tracking, and thus can't make things simple), the article's got it the wrong way around.

When code has abstract interfaces for data access, introducing caching can be simpler (but not simple) by localizing it in the abstraction implementation which has or doesn't have caching.

But it is not an abstraction (you can perfectly well do caching without any abstractions, and it's frequently done exactly that way).

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movpasd ◴[03 Jul 25 19:33 UTC] No.44458432[source]▶
I think you and the article are referring to abstractions over different concerns.

The concern you're talking about is about the actual access to the data. My understanding of the article is that it's about how caching algorithms can abstract the concern of minimising retrieval cost.

So in some ways you're coming at it from opposite directions. You're talking about a prior of "disk by default" and saying that a good abstraction lets you insert cache layers above that, whereas for the author the base case is "manually managing the layers of storage".

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1. foldU ◴[03 Jul 25 19:40 UTC] No.44458485[source]▶
This is correct, I appreciate you for putting it so coherently :). I think I didn’t make it clear enough in the piece that I’m coming from a stance of fast access being table stakes, and the question being about how that’s accomplished.
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2. necovek ◴[03 Jul 25 20:41 UTC] No.44458995[source]▶
"Caching" is an idea of storing a result of an expensive computation in storage that is faster to get from than doing the original computation (in very generic computer terms, computation can be simply fetching from the network or slower local storage).

What you describe as "caching algorithms" are not really caching algorithms, but cached object lifetime management algorithms (LRU, LFU...).

"Abstraction" is a higher level, simplified view of a set of concepts, yet caching is a single concept. See eg. https://en.wikipedia.org/wiki/Abstraction_(computer_science)

It sounds like you are both trying to redefine what "caching" means (tying it to implementations of particular algorithms), but also what "abstraction" means.

We should be very deliberate with the language we use, and our main goal should be to make it simpler to understand, not harder — I believe you are doing the latter here.