Separate DB

[A.J. Angel]

Originally Posted by Mr Spock

Should I use a separate db for each blog domain I set-up?

Use them separately!

Using one database may be easier to back up and update but one corruption and all blogs are affected while using multiple databases may be a hassle to back up and update but it's worth it especially if corruption happens. In that case, only one blog is affected, not all of them.

I also have to point out that nowadays, backing up and updating your blogs are made easier with plug-ins that do them automatically for you.