Re: pg_migrator issue with contrib

Bruce Momjian <bruce@momjian.us> writes:
> Tom Lane wrote:
>> There is a different problem though: sometimes the recommended fix for
>> contrib-module incompatibilities is to load the new contrib module into
>> the target database before trying to load your old dump file.  (We told
>> people to do that for 8.2->8.3 tsearch2, for example.)  In the
>> pg_migrator context there is no way to insert the new contrib module
>> first, and also no way to ignore the duplicate-object errors that you
>> typically get while loading the old dump.

> Ah, OK, interesting.  We could have pg_migrator detect this issue and
> fail right away with a message indicating pg_migrator cannot be used
> unless those objects are dumped manually and the /contrib removed.

How would it detect it?  I think the only thing you could do is
hard-wire tests for specific objects, which is klugy and doesn't
extend to third-party modules that you don't know about.

In most cases where there are major incompatibilities, attempting to
load the old dump file would fail anyway, so I don't think pg_migrator
really needs any hard-wired test.  It's the minor changes that are
risky.  I think ultimately the burden for those has to be on the module
author: he has to either avoid cross-version incompatibilities or make
sure they will fail safely.
        regards, tom lane