in reply to Re^3: Why did DBIC overtake CDBI?
in thread Why did DBIC overtake CDBI?
I'm not sure if there's an easy way to use it to fake joins across databases though.
If by "database" you mean "database server instance" (i.e., a different $dbh) then no, RDBO can't join across that when fetching multiple objects.
When dealing with a single object, however, it's possible to pull related objects from other databases. e.g.
$p = Product->new(id => 123)->load; # row from products table in db #1
$v = $p->vendor; # related row from vendors table in db #2
But all the multi-object "all at once" fetching is done using SQL JOINs, which don't work against separate database server instances.
Now if by "database" you mean something like a MySQL database (e.g., foodb.sometable and bardb.othertable) or a Postgres schema (e.g., public.table1 and alternate.table2), then yes, RDBO should be able to JOIN across those because they are addressable in a single SQL query run on a single $dbh.