Re: Removing pg_migrator limitations

Bruce Momjian <bruce@momjian.us> writes:
> Tom Lane wrote:
>> I think you're just creating useless work for yourself by imagining that
>> pg_migrator is backend-version-independent.  In fact, I was thinking
>> about proposing that we pull it in as a contrib module.  Because so much
>> of what it does is tied to details of backend and pg_dump behavior, it's
>> just a pipe dream to think that developing it as a separate project is
>> helpful.

> Well, I do think it will work for 8.3 to 8.4 ,and 8.4 to 8.5 --- I test
> that regularly and I have not seen any failures in that regard.  If we
> move it into /contrib, I will make sure fixes get backpatched.  FYI, a
> typical test is:

>     if (GET_MAJOR_VERSION(ctx.old.pg_version) <= 803 &&
>         GET_MAJOR_VERSION(ctx.new.pg_version) >= 804)

Well, yeah, you can probably make it work if you're willing to carry
enoguh version tests and alternate sets of logic in the source code.
I don't think that is a particularly good engineering approach however.
It makes things less readable and probably more buggy.  Particularly
so since we are talking about some quite significant logic changes here.

There's a reason to clutter, eg, pg_dump with multiple version support.
I don't see the argument for doing so with pg_migrator.  Separate source
code branches seem like a much better idea.
        regards, tom lane