I am often wondering if large webservices can run on old-school monolithic relational databases. It would be great because being able to simply model your applications data model as a set of SQL tables with strong constraints about data types and relations has huge benefits. But a single computer can only have that many cores and that much memory, so how far do modern monolithic database systems actually scale? And is Postgres going to be enough for Lemmy?

I stumbled upon the linked article on twitter. And it seems impressive. They are running their two billion dollar IT business on one single managed postgres instance. They started to migrate away from that when they hit the two billion mark in 2020. But instead of choosing a NoSQL system, they chose to stick with Postgres. They split groups of tables into different database instances.

Given that a two billion dollar company can run on a single Postgres instance like that, I have high hopes that no Lemmy instance will ever hit a limit with that.

At the moment it seems though that some parts of lemmy use Postgres in an inefficient way, so there may be some engineering necessary. But in the end I am positive that even an instance with 100k users should be able to run lemmy as it is, with a single postgres instance.