[CentOS] Re: Why is yum not liked by some? -- CVS analogy (and why you're not getting it)

Les Mikesell lesmikesell at gmail.com
Fri Sep 9 19:42:37 UTC 2005

On Fri, 2005-09-09 at 14:04, Bryan J. Smith wrote:
> Les Mikesell <lesmikesell at gmail.com> wrote:
> > Please explain what would go wrong if yum simply ignored
> > the presence of files newer than a specified date.   
> No offense, but build a YUM repository and you'll know
> _exactly_ why we think you are _clueless_ in this thread.
> The YUM client does _not_ access the RPMs, it accesses the
> repodata which is a meta-data listing of what is in the
> repository.  That meta-data listing is set to a _specific_
> set of RPMs at a _specific_ time.

I realize I'm asking for something yum doesn't already do.

How hard is it for you to find the timestamp of the rpm
in question or the yum header file for it.  You are right
that I don't know what is already stored in that up-to-100k
of metadata header file that yum gathers for every available
rpm, but if a timestamp isn't already in there it doesn't
seem like that much extra to add one. Or to just pick up
the timestamp from the RPM file itself via http/ftp or
any of the ways that mirroring techniques use.

> > All I'm asking for is a way to access what was done last
> > week (which is still there)
> *WRONG*!
> The RPMs are still there, yes.
> But the meta-data listing is _not_, it's _gone_.

Wait... Are you saying that if I tell yum to install
program-1.2.3 after program-1.2.4 appears in the
repository it will no longer correctly resolve the
dependencies?  I thought the metadata in the hdr
files was derived from the rpm dependency listings
and would thus be unchanged by subsequent additions.
> You keep thinking the YUM client can automatically and
> arbitrarily pick and choose among RPMs exist in the
> repository.  The thing is that the YUM client _only_ picks'n
> chooses what the meta-data listing says.

I thought the metadata consisted of the available hdr files.

> And there is _no_ information in that meta-data to say "give
> me the state of the repository on date X" if the meta-data
> was generated on date Y.  There is _no_ "YUM service" on the
> server that can dynamically generate this.

If the subsequently added hdr files were ignored, you should
have the state of the repository at that earlier time.
Otherwise what was the point of using separate files?  The
'delta' that you keep talking about is exactly these additional
hdr files.  Remove them or pretend they aren't there and the
yum client sees the prior state.

  Les Mikesell
     lesmikesell at gmail.com

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