DEV Community

loading...

Discussion on: Cache-Aside Pattern

Collapse
husniadil profile image
Husni Adil Makmur Author

Hi, thanks for the feedback.

I think in such an example, you pointed out, like just fetching data from a database there is no real need to have an external caching service deployed.

Yeah, I might put a very simple example that looks overkill to implement cache-aside pattern for such problem space, you're right. But I did this for the sake of simplicity. All comes back again to the real use case.


By optimizing and adding more memory to the MySQL instance you may also achieve near the performance like with redis (with less complexity). You just have to make sure that the cache (query and results) inside MySQL is big enough to fit as much pages in it. You would not have to deal with TTL, cache hit/miss and so on. Furthermore you would also have the single instance of thruth.

By tuning up MySQL, it should be able to withstand more traffic. But I think there are also trade-offs, for instance we need to aware the maximum numbers of database connections, and need more bucks for better machine specs.

I believe there's no silver bullet to handle this problem. There are some benefits when we separate the read model for this, for example if there's a heavy locking on MySQL during writes, the customer-facing app will still serves quickly on a warm cache situation, versus no cache at all.


Of course you are welcomed to read about the results I managed to achive with my in-memory cache (also in Go). I've also conducted much performance evaluations.

This is interesting, I might miss on finding on how you handle cache invalidation when there are some data being updated (not inserted) into the database during heavy reads. Will the app serve stale data for a longer period of time until no one is accessing the endpoint?

Collapse
davidkroell profile image
David Kröll

This is interesting, I might miss on finding on how you handle cache invalidation when there are some data being updated (not inserted) into the database during heavy reads.

Thanks for the reminder, I maybe missed this out (this piece of software is already two years old). But the idea of course was to update the cache first and afterwards the database.

Will the app serve stale data for a longer period of time until no one is accessing the endpoint?

I do not fully understand you question, but I've created a manager goroutine which cleans up the cache based on the configuration here:
github.com/davidkroell/shortcut/bl...

Thread Thread
husniadil profile image
Husni Adil Makmur Author

I do not fully understand you question

When a particular data it's still being accessed by many users in specific time range, that specific data will still be in the cache, although there's an update data request coming up from another endpoint. Thus new users is getting stale data (old data prior update).

Eventually, after no one is accessing the data for a period of time, the data will be deleted by the cache manager. CMIIW.