One alternative is using "data virtualization" tools like Denodo Virtual DataPort, that create the illusion of a single relational RDBMS and let you perform joi

One alternative is using "data virtualization" tools like Denodo Virtual DataPort, that create the illusion of a single relational RDBMS and let you perform joins between different databases (disclosure: I work at Denodo). I wrote about it here: http://productivedetour.blogspot.com.es/2014/12/connecting-to-denodo-virtual-dataport.html http://productivedetour.blogspot.com.es/2014/12/connecting-t...