I'm comfy with Postgres though, like I'll center my entire backend around it and do the heavy lifting in SQL (never ORM). It's more that I don't want to depend on a cronjob for something as fundamental as a cache.
Usually Postgres costs a lot more than Redis if you're paying for a platform. Like a decent Redis or memcached in Heroku is free. And I don't want to waste precious Postgres connections or risk bogging down the whole DB if there's lots of cache usage, which actually happened last time I tried skipping Redis.
I can understand being nervous about some cron job running on some other service, but what's concerning about a cron job managed inside of Postgres with pg_cron? If that doesn't run, your database is probably down anyway.
Postgres might cost more but I'm probably already paying. I agree that exhausting connections and writing at a high rate are easy ways to bring down Postgres, but I'm personally not going to worry about exhausting connections to Postgres until I have at least a thousand of them. Everything has to be considered within the actual problem you are solving, there are definitely situations to start out with a cache.
I might be ok with this if it were built in, but pg_cron is an extension, so first off you might not even have access to it. And then you still have to monitor it.
Heroku doesn't have it. That's actually kinda annoying that they don't, cause the others do. AND they no longer have free Redis, so that changes things a bit.
> Usually Postgres costs a lot more than Redis if you're paying for a platform.
You need to back up your unbelievable assertion with facts. Memory cache is typically far more expensive than a simple database, specially as provisioning the same memory capacity as RAM is orders of magnitude more expensive than storing the equivalent data in a database.
Why are you confusing memory capacity as a requirement to store the whole database in memory? I mean, think. What do you think is the biggest performance bottleneck with caches, and how does this relate to memory capacity?
I didn't say it's cheaper for the same cache size. But yeah a base tier Redis that will carry a small project tends to be a lot cheaper than the base tier Postgres.
Usually Postgres costs a lot more than Redis if you're paying for a platform. Like a decent Redis or memcached in Heroku is free. And I don't want to waste precious Postgres connections or risk bogging down the whole DB if there's lots of cache usage, which actually happened last time I tried skipping Redis.