If it can be stuck in a sqlite database and run on a developer laptop, then no, it is not medium by any standard.

Please elaborate why you think 50Gb is anything other than a small dataset that can fit in memory on any half-decent server though.

[edit] in the spirit of not being a condescending tool to you, i'll replace my original reply with this: https://en.wikipedia.org/wiki/Long_tail

I'm assuming this is a joke. You can run databases that size without any of the fancy scalability stuff - no sharding no anything. I'd actually recommend that, it's makes admin super easy!