dual database design --- opinions?

[Chris Bassett]

I'm going to start writing a database application that will be used for allowing users to register products, thus recording customer information and purchase information.

I as thinking of doing this with two separate databases. One would be a "user data" database that would hold data that would be changed on a daily basis. The other database would be more of a "static" database, that would not be changed very often.

My thoughts behind doing this is that all trasactions would require both databases to be read, but only the "user data" database would have changes being made. I was thinking this might speed up the processing of the "user data" database...? Both databases are hosted on the same MySQL server host.

Does it matter if I use two separate databases or should I just compile both database together into one for ease of maintenance? Is there any performance gain by using two of them versus one single database?