Re: Inline Extension

On Sun, Jan 22, 2012 at 3:20 PM, Daniel Farina <daniel@heroku.com> wrote:
> A few anecdotes does not constitute evidence, but it does look like
> some people pay attention to any additional versioning foothold they
> can get.

Sure, but just because some people do it doesn't make it a good idea.
I can personally attest to having done many things over the years
which initially appeared to be good ideas, but later turned out to be
mind-bogglingly dumb.  It's true that if we make it easy for people to
use the extension mechanism as a way of storing versioning information
for user code, then people will use it for that purpose, but the
question is whether that's really what we want.  I don't see what
advantage it gives us.  Dimitri's proposal was to neuter the pg_dump
support that is the raison d'être of the extension mechanism.  That's
clearly necessary if you don't want to end up with an unreloadable
database, but it begs the question (which no one's really answered
AFAICT) of what good the extension mechanism is without that feature.
There are certainly easier ways to remember a version number than
building support for it into core.  If people create their own
versioning mechanisms, they can create something which is tailor-made
for their particular requirements, rather than relying on decisions
which we made in core that may or may not be right for them (e.g. the
lack of version ordering, or even that we have versions rather than
some more general type of control table).  I don't want to prejudge
the outcome and say, oh, we should never have support for this concept
in core - but neither do I want to embark on that project without a
detailed understanding of where and how it is adding value.  If people
are doing management via "pure FEBE", good for them: but that doesn't
explain why it shoudn't be done all in userspace, with all of the
flexibility that gives.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company