In praise of memcached

tempest_ an hour ago | parent | next [-]

I stopped using memcached a decade a go in favour of Redis and now use valkey.

Never felt the need to go back to memcached except when a legacy dependency needed it.

	▲	jimbokun 30 minutes ago \| parent [-]
		OK. What do you think of the argument made in the article?

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jszymborski an hour ago | parent | prev | next [-]

An article praising memcached and no mention of the feral bunny mascots.

	▲	abound an hour ago \| parent [-]
		> And look at those cute little mascots at the top!

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kijin an hour ago | parent | prev | next [-]

Redis works great as a cache, but there are a few things you need to do in order to use it reliably as a cache.

1) Wrap your client library so that it's impossible to store anything without an expiry date. You don't want 6-months-old data suddenly coming up in your app!

2) Either turn off persistence, or use a separate database for the cache. In other words, don't mix volatile data with stuff you actually care about.

3) Set up a reasonable maxmemory value with an appropriate maxmemory-policy, so that Redis doesn't eat up all your RAM.

4) Resist the urge to use complex data structures. If you try to update a single field on an expired hash, you will end up with an incomplete object.

If you don't want all that hassle, then yes, Memcached probably works better out of the box.

	▲	dvt an hour ago \| parent [-]
		> 1) Wrap your client library so that it's impossible to store anything without an expiry date. You don't want 6-months-old data suddenly coming up in your app! No need for this client-side complexity, as you should be using `allkeys-lru`. FWIW, should likely be doing this anyway, as (generally speaking) all data stored in Redis is usually regarded as volatile because of what Redis actually is.

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dvt an hour ago | parent | prev | next [-]

Memcached is meant to be a lightweight memory cache, which makes sense, but contrary to the article's claim that "Redis is brought into a stack as a cache, and it is run with the assumption that people treat it that way"—I have very very rarely experienced this. Redis is brought into a stack because (most importantly!) it's fast and (almost as importantly!) because it's simple. I don't think this article is written by AI, but (and I'm trying to be charitable here), it's just like.. dumb.

> Dealing with memcached downtime is incredibly easy, because client libraries generally ignore connection exceptions. For instance, a simple get will just return the default value (or none) if the server is down.

This is a terrible idea in the context of things that might use Redis. If you use Redis with some kind of complex state (say, a document if you're working on a Notion clone, for instance), wtf even is a "default value"? In fact, I actually also want to know when the thing is down.

> Clustering memcached is wonderful, because memcached actually has no clustering built-in.

Yeah bro, this is yet another one of the reasons people use Redis: it handles consensus and clustering for you. What even is this article? It's a master class in straw-manning architectural decisions: most people use hammers as hammers, but screwdrivers make great hammers too, especially if you also need to screw stuff in! I mean.. technically true?

	▲	groundzeros2015 an hour ago \| parent \| next [-]
		> it handles consensus and clustering for you Considering how complex and error prone this is, I don’t want it in my stack.
	▲	jszymborski an hour ago \| parent \| prev \| next [-]
		> wtf even is a "default value"? The article mentions the default value is a null, which would be the cue to run whatever computationally expensive op or query the db or hit the disk etc... that you would normally run if you had no cache to begin with. > but screwdrivers make great hammers too I don't know what your screwdrivers look like but that sounds like a rough time.
	▲	foobarian an hour ago \| parent \| prev [-]
		The memcache slab pools are a leaky abstraction that you may end up having to manage operationally, and it's another way Redis is simpler.

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abofh an hour ago | parent | prev [-]

Oh God I'm tired of ai written thought pieces

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hoppoli 40 minutes ago | parent | next [-]

I see this comment frequently in this site and it doesn't provide any value. If this isn't part of the hackernews rules, I hope it becomes one soon.

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newfocogi an hour ago | parent | prev | next [-]

I don’t think LLMs would write this:

“Anyways, Redis homepage aside, you deploy it, and off you go - your trusty cache. You hand the connection string to the people who asked for it, and off you go.”

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abofh an hour ago | parent | next [-]

So many it's not X it's Y. It might have been polished, but it was claude

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newfocogi an hour ago | parent | prev [-]

Or this:

“None of these things are impossible with Redis, it’s just that memcached’s architecture in general more leans towards these directions, which makes it much, much more straightforward from an operations point of view.”

	▲	chipotle_coyote an hour ago \| parent [-]
		It's become de rigueur on HN to accuse any article one thinks is trite, obvious, or simply disagreeable of being AI-written. ("That comment has three items in a list! No human would ever put three items in a list! Checkmate, bot!")

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poly2it an hour ago | parent | prev | next [-]

I don't see how this is AI-written?

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throw310822 an hour ago | parent | prev [-]

Somebody call Deckard.