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Re: Pre-Depends for postgresql


Please don't get me wrong, I don't insist of using adduser. IMHO
Mathieu's solution of checking whether adduser is available is
acceptable, if adduser is not installed then I can't break any admin
preferences anyway. In addition, user postgres has uid 31, thus
base-passwd should have given its blessings to postgres :-)

But I would like to understand this issue properly. Thus I am
bothering you again (sorry :-) ):

On 2003-10-17  2:14 +1000, Russell Coker wrote:
> If you depend on a less important package then it would be an indication that 
> one of the packages in question has the wrong priority and therefore a bug.

That's obvious.

> If you pre-depend on an equally important package then there may be issues 
> related to circular-dependencies at some future time.

I understand, but that doesn't hold here.

> If you have a non-base package pre-depend on a base package then the base 
> package can never depend on it (base packages must not depend on non-base 
> packages).  

That's basically the same as the first paragraph.

> If you have an "optional" package depend on a package that is
> "important" or "required" then again it would be a bug for any other
> package to have a dependency that results in a circle leading back
> to your package.

This confuses me. If a package can neither pre-depend on a package
that has a lower, an equal, nor a higher priority, then we wouldn't
need pre-dependencies at all. Could you convince an example?

> So no matter what happens if you have postgres keep it's current
> section and priority (I can't see postgres becoming a base part of
> Debian or being considered important in the Debian priority system)

Well, making a huge beast like postgres standard or even part of base
is certainly not desirable...

> then any problem related to your pre-depends will be a fairly
> obvious and unambiguous bug in someone else's package.

Could you explain this in more detail, please? Maybe with an example?

Currently, postgres is already using adduser in its preinst, but only
depends on it (which is kind of "too late"). The question is now,
should we make it officially pre-depend on it or should I convince
Oliver to rewrite the stuff to fall back to useradd (BTW: Oliver, do
you follow this?)

> I've recently learnt about some of these things the hard way...  ;)

I believe that and that's the reason why I want to understand this

Thanks in advance for the time you spent to teach newbies! :-) The
policy only explains the purpose of pre-depends and I didn't find
anything in the Developer's Reference.

Have a nice day,

Martin Pitt
home:  www.piware.de
eMail: martin@piware.de

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