[Server-devel] PostgreSQL mgmt on Fedora: pg_cluster-like tools?

[Martin Langhoff]

2008/9/12 Devrim GÜNDÜZ <devrim at gunduz.org>:
> I am *very* against this one. It is not packager's job to run
> dump/reload:

I agree with you in a normal rpm package. I am working to some very
special requirements :-)

> * You may never be sure that it will work. We had this issue in 8.3 for
> example.

Yes, I've overseen many 7.2/7.3/7.4/8.0/8.1/8.2 migrations and
understand the pitfalls fairly well.

> * Upstream never ever gives such a guarantee that all apps will work on
> every PostgreSQL version. For example, some casts were removed in 8.3.

Having been once the maintainer of the Pg compat layer in Moodle, I
also have first-hand experience with this. When the casts removal was
mentioned in pg-devel, who was there asking about backwards compat?
;-)

> So dumping/restoring should be a DBA work. So "switch over if it was
> successful" is really a bad idea, and *will* break things.

We'll have ~5K school servers in rural schools just in Peru, a team of
perhaps 10 sysadmins for them, most of the servers disconnected.

OTOH, we know what apps talk to Pg, and we'll have tested them
thoroughly. The failures could come from data that breaks during
migration - so if an 8.3 to 8.4 migration fails to complete we keep
running on Pg 8.3, and write a log.

(This is assuming that 8.4 has improvements worth the migration risks.
We'll probably defer until a version of Pg has significant benefits to
actually do this...)

quite a challenge - :-)



m
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 martin at laptop.org -- School Server Architect
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