Re: pg_migrator issue with contrib - Mailing list pgsql-hackers

Robert Haas wrote:
> > Let me list the problems with pg_migrator:
> >
> > ? ? ? ?o ?/contrib and plugin migration (not unique to pg_migrator)
> > ? ? ? ?o ?you must read/follow the install instructions
> > ? ? ? ?o ?might require post-migration table/index rebuilds
> > ? ? ? ?o ?new so serious bugs might exist
> 
> I pretty much agree with this list.  With respect to #2, I don't think
> that it's asking a lot for people to read/follow the install
> instructions, so I don't consider that a serious problem.

My point was that I think someday pg_migrator will be point-and-click,
but it is not now.

> Oh, to me "experimental" does not imply that usefulness is uncertain;
> rather, it implies that usefulness has been established but that the
> code is new (item #4 above) and may be not be 100% feature-complete
> (items #1 and #3 above).
> 
> > I think we can say: ?"pg_migrator is designed for experienced users with
> > large databases, for whom the typical dump/restore required for major
> > version upgrades is a hardship".
> 
> Precisely.  In other words, if you are an INEXPERIENCED user (that is
> to say, most of them) or you don't have a particular large database,
> dump + reload is probably the safest option.  We're not discouraging
> you from use pg_migrator, but please be careful and observe that it is
> new and has some limitations.

Agreed.  There is no reason for most users to need pg_migrator;  it is
not worth the risk for them, however small.  There are some people who
really need it, and hopefully they are experienced users, while there is
a larger group who want to know such an option _exists_, so if they ever
need it, it is available.

> > I assume this will be the same adoption pattern we had with the Win32
> > port, where it was a new platform in 8.0 and we dealt with some issues
> > as it was deployed, and that people who want it will find it and
> > hopefully it will be useful for them.
> 
> Completely agree.  And like the Windows port, hopefully after a
> release or two, we'll figure out what we can improve and do so.  I am
> interested in this problem but all of my free time lately has been
> going into the EXPLAIN patch I'm working on, so I haven't had time to
> dig into it much.  The problems of being a hobbyist...

One difference in risk is that the Windows port usually had _new_ data
meaning you were not risking as much as using pg_migrator on an
estabilished database installation.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + If your life is a hard drive, Christ can be your backup. +