Hi, drill devs: I'm developing a storage plugin for our own storage engine and I'm confusing about the SubsetTransformer class while reading the source code. It seems that its goal is to find all physical implementations of an input and add it directly to the current as input. But I think this maybe unnecessary since volcano planner will search rules and do the transformation for us. What I guess is that this can accelerate the optimization process. -- Liu, Renjie Software Engineer, MVAD
