Re: Which postgresql should i choose to migrate from 8.3 ? 8.4 or 9.1?

On Tue, Aug 28, 2012 at 9:52 AM, Ing.Edmundo.Robles.Lopez <
erobles(at)sensacd(dot)com(dot)mx> wrote:

> Hi!
> We are using postgresql 8.3 in my work, and the need to migrate to a newer
> version became urgent :)
>
> I've been reading the release notes for versions 8.4 and 9.1, but is not
> clear to me which problems I can have with version 8.4 or 9.1 from a dump
> 8.3
>

Just as a note, you will have far fewer problems if you can use the newer
version's dump programs against 8.3 than if you try to dump with 8.3 tools
and restore in later versions.

>
> My boss thinks we would have fewer problems if we use the version 8.4, I
> believe that it is best to have version 9.1, and the number of problems
> will be the same as in version 8.4
>

I think the sorts of problems you have are likely to be different. 8.4 is
likely to be the easiest migration, it is true. I can tell you as far as
LedgerSMB goes, we had the most trouble with 8.3 and 9.1 when they came out
because of changes that specifically affected us in those releases (the
extension system was the big one in 9.1).

Your tradeoff is basically this: The more major versions you move up, the
more likely you are to have immediate issues, but you can buy more time
between major version upgrades and the backwards-compatibility-breaking
improvements usually are significant improvements, so you may have more
work in the migration but then you have a better ability to be cautious
about moving forward.

>
>
> In favor of version 9.1 is that it will be supported until 2016.
>
>
> What is the structural difference or what was the reason to have a version
> 9 and version 8?
>
>
To be honest, you can't put a lot of stock in whether it was named 8.5 or
9.0. Every application is unique. Every major version (8.4, 9.0, 9.1,
9.2) will introduce backwards-incompatible behavior and much of this is
actually an improvement once you get the specific problems you have fixed.
As I say the move from 8.2 to 8.3 hit us pretty hard because of the
casting changes. 9.0 didn't cause any problems for us at all (neither did
8.4). 9.1 caused us to have a number of installation issues since we
depend on contrib stuff that took a while to get sorted out but would have
been tolerable if we were not distributing software.

>
>
>
> Please, could you help to give peace of mind to my boss and make sure that
> the version we choose to be as smooth as possible compatible with version
> 8.3?
>
> indeed to restore the dump of the 83 in 9.1 had a bug in UTF-8, will I
> have the same problem with the 8.4???
>

Always use the new tools to back up the old db during migration. So if
moving from 8.3 to 9.1, use the 9.1's pg_dump. Otherwise you can expect
problems.

>
> What will be the problems you have had to migrate from version 8.x to the
> 8.4 or 9.1???
>
> is it a good idea migrate to 9.1 rather than 8.4?
>

If it were my organization I'd start doing this on a separate server for
testing purposes (use the pg_dump from the new server to back up the data
from the old server). Then I'd run tests and see what the gaps were. Then
depending on urgency, I would ideally choose to fix those problems and then
migrate. However, if it is particularly urgent, I might scale back to 8.4
and try again.

> Perhaps, it would be a good idea to have a page on the postgresql site
> which is titled: How to convince my boss to install latest version. ;)
>

Best Wishes,
Chris Travers