On Wed, Aug 27, 2014 at 10:13 AM, Bruce Momjian <bruce@momjian.us> wrote:
> On Wed, Aug 27, 2014 at 09:54:11AM -0400, Robert Haas wrote:
>> Having said that, there are obviously advantages for our users if we
>> don't get too crazy about requiring that. I've used products in the
>> past where to get from version 3 to version 11 you have to upgrade
>> from 3 to 5, then 5 to 7, then 7 to 9, and then 9 to 11. That's
>> somewhat understandable from the vendor's point of view, but it's not
>> a lot of fun, and I think we should definitely avoid imposing those
>> kinds of requirements on our users.
>>
>> What we're talking about here is much milder than that. For the
>> pg_upgrade case, you can upgrade from 8.3 to any of 8.4, 9.0, 9.1,
>> 9.2, 9.3, and 9.4. You only need to do a two-step upgrade if you want
>> to leapfrog more than 6 major release versions. That seems like a
>> wide-enough window that it shouldn't inconvenience many people. For
>> the pg_dump case, you can upgrade from 7.2 or 7.3 to 7.4, 8.0, 8.1,
>> 8.2, 8.3, 8.4, 9.0, 9.1, 9.2, 9.3, or 9.4; that is, 11 or 12 major
>> releases. The number of people who want to skip more than a dozen
>> releases in a single upgrade should be very small, and we might
>> council those people that they'd be better off with a step-wise
>> upgrade for other reasons - like the application-level compatibility
>> breaks we've made over the years - anyway.
>
> Two things --- first, removing 8.3 support in pg_upgrade allowed me to
> remove lots of dead code, so it was a win. Second, I think you need to
> look at the time span from old to new versions to understand if a
> double-step release is reasonable. If that 3-5-7-9 release step spans
> two years, it is too short --- if it spans 15 years, it is probably fine
> as few people would wait 15 years to upgrade.
Right, I agree with all of that and was not intending to dispute any of it.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company