Gavin, That is certainly one nice tool. The visualization system and the listeners are nice (though it does not seem to work on larger plans with lots of planning steps) , but its still not clear to me what some of the symbology means. For example, a subset has several children, one of which is purple, and the other is light turquoise.
In my case, the problematic collection of sets and nodes is relatively small relative to the overall query, so the graphvis rendering is much smaller. With the RuleMatchVisualizer, the tree is so large that it does not render at all at the last step (I assume that the last step is also the step where the CannotPlanException is thrown) Maybe this is all easier to understand if I were to have a better understanding of the VolcanoPlanner infrastructure? -Ian
