Ask HN: How to traverse a transitive closure tree in preorder?

Hi

I'm working on a transitive closure tree implementation. I seem to have managed to implement everything else I need except a way to traverse the tree in preorder.

I've been using http://www.slideshare.net/billkarwin/sql-antipatterns-strike-back from page 68 as a reference for the build.

Currently I use depth to order the descendant call, which gives me a very quick level order result.

Anyone got any idea how to run a preorder traversal on this type of data structure?