> What I would like to know is, if I have changed some ot the modules,
> how can I use GNU gdb to debug the modified codes?
You can run the backend directly from gdb:
$ gdb postgres
(set breakpoint)
> b <routine_to_breakpoint>
(tell gdb to begin)
> run -D <path_to_database>
(enter query at prompt)
> select xyz from abc...
(will run until it hits the breakpoint(s))
- Thomas