Hi,

I found one thread on this that included some people's opinions, but I
haven't been able to find anyone who has actually done some performance
testing to see if there is a cost and what that cost is to doing cross
database joins. I do tend to want to keep everything in one DB, but it
gets hard when you have databases that do cross over at times, but
rarely. Of course I am being somewhat lazy in doing this post, but only
because I think someone here *must* have already done some testing
between cross db joins and inside db joins. Another point of interest is
if DBI actually opens another connection or not. I saw one mention of a
worry about that, but as I understand it, you can refer to any table in
any database from any mysql connection that has permission to access
that DB and table, so you should be able to access any DB from any
initial connection.

Thanks,

Eric