[markandrewj]

Scaling databases vertically, like Oracle DB, in the past was the norm. It is possible to serve a large number of users, and data, from a single instance. There are some things worth considering though. First of all, no matter how reliable your database is, you will have to take it down eventually to do things like upgrades.

The other consideration that isn't initially obvious, is how you may hit an upper bound for resources in most modern environments. If your database is sitting on top of a virtual or containerized environment, your single instance database will be limited in resources (CPU/memory/network) to a single node of the cluster. You could also eventually hit the same problem on bare metal.

That said there are some very high density systems available. You may also not need the ability to scale as large as I am talking, or choose to shard and scale your database horizontally at later time.

If your project gets big enough you might also start wanting to replicate your data to localize it closer to the user. Another strategy might be to cache the data locally to the user.

There are positive and negatives with a single node or cluster. If retools database was clustered they would have been able to do a rolling upgrade though.