Question

Why Q2A is not using redis it is better than memcached?

Comments

What are the advantages (as a web-cache) Redis provides over memcached?

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Redis vs Memcached for WordPress - Which Is Better? : https://youtu.be/j_mjvkhZG18

Choosing between Redis and Memcached : https://aws.amazon.com/elasticache/redis-vs-memcached/

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Features Redis has that memcached doesn't: Advanced data structures, Snapshots, Replication, Transactions, Pub/Sub, Lua scripting, Geospatial support. None of them are relevant for Q2A AFAICS, so why waste time and resources on integrating a software that doesn't provide an advantage? Please don't jump on hype trains.

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oh ok.... correct ............... I was just trying to install memcached then I found Redis.

Answer 1

I used Memcached because it seemed more common in the PHP world, probably because it's been around for longer. I thought it would be available on more hosts (though I don't know if that's 100% accurate as I couldn't find hard stats).

Memcached is also simpler and apparently more memory-efficient for our use case in Q2A.

My intention was to add a new plugin type to allow users to use a different type of caching, but I never got around to it. You could do it with a core hack in qa-src/Storage/CacheFactory.php if you wanted to use Redis.