Miles Keaton <mileskeaton(at)gmail(dot)com> writes:
> When I do a pg_dump, (--data-only), PG7 used to dump the data out in
> order, so that all foreign-key checks worked correctly when loading
> the data back in.
If it did so, it was by pure luck.
In general it is not possible for pg_dump to guarantee this works;
consider circular FK constraints, or FK constraints added since the
dump occurred. In view of that, pg_dump has never tried to ensure
that data-only dumps are in a "valid" order at all. The usual
approach is to use --disable-triggers to short-circuit the FK
constraints during the load.
regards, tom lane