I asked a question on here a couple of days ago and got some really good answers, i'm thinking about doing a facebook style website with profiles, bio's, etc, and asked whether i should use mysql, the answers were to use Cassandra because its much better. I'm just asking is this what everyone would suggest, its just i know mysql fairly well and would it be a completely stupid move on my part to use mysql over Cassandra (which i hadnt even heard of until 2 days ago)
thanks
Go for MySQL. Cassandra will make development hard, it still lacks tools, tutorials, etc. And it's rapidly changing, so you'll have to change your code as well.
Take a look at this article - it explains why I think it's not yet the time for regular projects to go for Cassandra.
In case your application sky-rockets and needs more scalability than MySQL provides, then you'll have enough people to handle the transition to Cassandra. Just abstract your Data access layer so that you can later switch without changing the rest of the code.
Update: Note the date of this answer. It is by definition going to get out of date, so check if there are already good tools, tutorials, etc.
来源：https://stackoverflow.com/questions/4068946/a-bit-of-advice-on-cassandra-vs-mysql