XML guru Norm Walsh, formerly of Sun, is now on the payroll at Mark Logic, a smart move for both Walsh and his new employer—and a big shock to some in the industry who can’t believe that he jumped ship. Walsh has already learned Rule 1 of Database Performance from Mark Logic CEO Dave Kellogg.

Norm writes about this experience on his blog, Thinking Differently About XML. “I was thinking about the problem from the wrong end,” Walsh wrote. “I had gone out and asked the server to give me a fairly big document and now I was trying to grub around inside it to find stuff. Instead, I should ‘push the constraints to the database’,” Walsh wrote. “Maybe I’m just discovering something that was obvious to all of you, but I’m now thinking of XML applications over not just a few files, but a whole database. My world is suddenly a lot bigger which is very cool.”