Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> ... Maybe we could find a way to reduce the size of the parse
> tree (i.e. fewer nodes), or the number of times that it has to be
> walked/copied.
We could eliminate some annoying tree-copy steps if we could institute
the policy that parse analysis doesn't scribble on the raw parse tree,
rewriter doesn't modify parse analysis output, and planner doesn't
modify rewriter output. However, it would be a lot of work, and I'm not
entirely sure that we'd end up with a significant speed benefit. In a
lot of places, the only way to not scribble on the input is to copy it
anyway ...
regards, tom lane