[Pkg-postgresql-private] System for managing multiple postmasters?

[Oliver Elphick]

On Wed, 2003-10-15 at 18:25, Martin Pitt wrote:
> Please forget about the binary update, this of course was crap. But
> nevertheless the problem persists. I just tried upgrading from 7.3.4
> (sid) to 7.4.0-beta4 (alioth) and upgrading failed:
...
> The pg_dumpall from 7.3 doesn't work any longer because of the changed
> libkrb5. I reinstalled 7.3.4 then, dumped the database with its
> pg_dumpall, then purged and reinstalled 7.4.0beta and fed back the
> dump which worked fine.

Oh dear, this means there is no way we can guarantee to do the upgrade
automatically.  We can't even use ldd to save _all_ libraries to
dumpall/ because they might have been deleted by the time the preinst
runs.

> Thus, it would be nice if during an upgrade the old version was
> responsible for dumping the database (i. e. do it in its prerm) and
> the new version for restoring it. By now, the new db does the dump
> which seems far less reliable. 

Yes, but the problems of doing a dump at any time during package
installation are bad.  We can't guarantee to have enough disk space
(which is why postgresql-dump offers a dump to tape option); we don't
want it to happen when we are just upgrading without a major version
change, and so on.

(I used to save the executables in the prerm, but if there's any bug
there, it is hell to get the package replaced.)

> Splitting the task had the disadvantage that it does not fit into a
> single script anymore, but at least in my case it had worked.
> 
> What do you think?

I think this demonstrates that the automatic upgrade is just too flaky
and needs complete rethinking.  This is why I started to consider
installing parallel major versions.  I think we have to go that way, so
that the new version can be installed before the old one is removed.

I'm going to be away for the next two days.  I may be able to look at
mail, but probably only in the evening.  In fact I will be away Thursday
and Friday every week for the foreseeable future.  This time I will try
to plan how to make the packages work in parallel.

-- 
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight, UK                             http://www.lfix.co.uk/oliver
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839  932A 614D 4C34 3E1D 0C1C
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     "If ye love me, keep my commandments."       John 14:15