Re: how to watch parse/plan trees

Hannu Krosing <hannu@tm.ee> writes:
> How do you people look at various trees and lists when debugging them ?

I tend to start psql with PGOPTIONS="-d2" and then look at the
prettyprinted trees in the postmaster log.

If you have a bug that prevents you from getting as far as the parsetree
dump, however, gdb is probably the only way.

> Also could anyone recommend any tools for debugging gram.y or is this
> also done mostly by hand even for large grammars ?

Once you've got rid of any shift/reduce or reduce/reduce conflicts
(bison -v output is helpful for that), I find that the grammar itself
seldom has any surprising behaviors that you need to use a debugger
to follow.
        regards, tom lane