I was keen to play with DQP so I decided to test it by pulling data from two databases. I have found the documentation descriptive enough but I will write the procedure I followed. Hopefully, it will be helpful to some.
I want to deploy OGSA-DAI Axis on Tomcat. I have a MySQL database on my machine and a Postgres database on another machine. My plan is to use DQP (which is bundled in OGSA-DAI 3.2) to do a join across these databases. I will deploy OGSA-DAI on my machine. I will then deploy two data resources, one for each database, and a DQP resource that includes these two resources. Finally, I will run some queries.