Re: Finer Extension dependencies

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Hmm .. feature names should be globally unique, right?  If so I think
> you're missing an UNIQUE index on the new catalog, covering just the
> feature name.  You have a two column index (extoid, featurename), so you
> could have two different extensions providing the same feature.  Is this
> okay?  If it is, then there is a bit of a bogus code in

You're right, this looks like something I forgot to go back to, the
unique index should be global on the feature's name.  I will go make
that happen (tomorrow).

> I noticed that you've left unspecified whether an extension should have
> a "provides" entry for itself or not -- I mean the code adds one if it's
> not there.  I'm not sure about this, maybe it's okay.  But this makes it
> impossible for it to say "provides: extname-0.5" and have a dependent
> extension fail if it only requires "extname", because that one will be
> provided automatically whether extname's author wants it or not.
> Again, maybe this is okay.

I think it is ok, at least that's how I intended the feature to work.
The use case I want to allow is for the other extension's author to say
its extension depends on the extname-0.5 feature. In fact I guess that
you would rather provide feature names, not version, so as not to have
to look up a feature matrix each time.

For the use case you're concerned with, I think that if an extension's
upgrade is not compatible with the previous version, the extension name
itself should be changed (extname2 or extname-1.0 or whatever).

Regards,
--
Dimitri Fontaine
http://2ndQuadrant.fr     PostgreSQL : Expertise, Formation et Support