[samdk]

It's not that postgres can't handle large tables, it's more that many of the ways it uses system tables aren't particularly optimized for them being large, so you're operating outside the territory the table/query design was probably built for.

Like most things postgres it'll probably still work better than it has any right to for a while, but it'd be extremely unsurprising if it caused you unexpected problems at some point. (And if it does, they'll likely excitingly novel and you'll probably have to dig pretty deep to understand what's going on.)

[swyx]

so is a good rule of thumb "put your users in postgres first until 100-500k, then revisit if you need to move to a dedicated solution"?

[IshKebab]

Probably not unless you like rearchitecting your entire security system when you already have 500k users!

[tuatoru]

That's probably easier than if you have only 2k. Although the special cases in the 500k might squeal a bit, they're more ignorable.