I'm working on a web app in which each user will have their own account. Each account would have its own data (duh) and this data needs to be kept separate from everyone else (either by putting it in another database JUST for that user or combining all data into 1 database and then marking it with a "userid" that can be used to filter out every one else stuff.
Which would be better: having a different database for every user (created on signup via sql and php) that is named after their userid? Or is it better to combine all of the info into one massive database and just earmark things with an indexed "userid"?
Performance might be an issue in the future so which is better for that?