Nextcloud asked in a poll at https://mastodon.social/@nextcloud@mastodon.xyz/115095096413238457 what database its users are running. Interestingly one fifth replied they don’t know. Should people know better where their data is stored, or is it a good thing everything is running so smoothly people don’t need to know what their software stack is built upon?
You seem to be obsessed with optimising one resource at the expense of others. Time is a limited resource, and even if it only takes 5 minutes to configure all of your containers to share a single db backend (it will take longer than that even if you just have 2), you’re only going to save a few MB of RAM. And since RAM costs roughly $2.5/GB (0.25 cents/MB) your time would have to be worth very little for this to be worthwhile.
On the other hand, if you’re doing it to learn more about computers then it might be worthwhile. This is a community of hobbiests, after all…
If you want to push it and paint me as obsessed about something, then let it be this: providing this community with on-topic and reasonable advice
This is false, and you should read once again my previous message illustrating why: on a decent “self-host”-friendly machine, the same software may work very well, or not at all, depending on whether the user would engage with very basic configuration. This goes beyond RAM (memory isn’t the sole shared resource), and I’m adamant that the alternative (which was “pretending that the problem doesn’t exist” turned into “throwing money at the problem”) is unreasonable.
Or more importantly: the extent to which you can self-host out of sheer luck and ignorance like you suggest is very limited. If you don’t want to engage with a minimum amount of configuration, you might bump into security issues (a much broader and complex subject) long before any of the above has a material impact.