7.2 -> 7.4: horrible performance hit!

[I'm not subscribed to this list, and i'm sending this because the man
that develop our internal application is away... so i'm not aware of
most of the detail, i'm only seeking to some quick fix, wait tomorrow
for some better and deeper info.]
[[so, please, keep me in CC]]

In our organization we have develop an internal application based on
LAPP, hosded on Debian GNU/Linux intel box.

We are proceeding to upgrade from woody (postgres 7.2.X) to sarge
(postgres 7.4.X), and missing our expectation we get impressive
performance hit. ;(

The application work well, apart some query that took some *MINUTES* to
complete, when on 7.2 take (half of) second(s). It's a postgres
problem, a simply ``top'' running on the database backend reveal that
the postmaster instance eat up 99% of the cpu for all the query
processing.

I've just tried what i consider the ``base things to do'':

+ dump and reload the database
+ do an ``vacuumdb --analyze --full'' on the database and test before
and after the query.

no sensible changes.

There's some differences between 7.2 and 7.4 that can be the cause of
this?

Please, help me.

--
dott. Marco Gaiarin GNUPG Key ID: 240A3D66
Associazione ``La Nostra Famiglia'' http://www.sv.lnf.it/
Polo FVG - Via della Bontà, 7 - 33078 - San Vito al Tagliamento (PN)
gaio(at)sv.lnf.it tel +39-0434-842711 fax +39-0434-842797

Grazie parlamento europeo!
http://punto-informatico.it/p.asp?i=53925&r=PI