Re: Problem with a transaction on dump

Alvaro Herrera wrote:
>
> Froggy / Froggy Corp. wrote:
> >
> >
> > Alvaro Herrera wrote:
> > >
> > > Froggy / Froggy Corp. wrote:
> > > > Hello everyone,
> > > >
> > > > It is the second time i got this error message (sorry, its french, i
> > > > prefer to c/p this one than making a bad translation) :
> > > >
> > > > -------8<------------8<-----------8<-----------
> > > >
> > > > pg_dump: ERREUR: Impossible d'accéder au statut de la transaction
> > > > 892415538
> > > > DETAIL: Impossible d'ouvrir le fichier
> > > > «/var/lib/postgresql/7.4/main/pg_clog/0353» : Aucun fichier ou
> > > > répertoire de ce type
> > >
> > > What files are there in main/pg_clog?
> >
> > 0000 to 0024
>
> FWIW, I examined the bit pattern in the number 892415538, which is
> 110101001100010010111000110010, and taken as octets interpreted as ASCII
> chars, they look like this:
>
> 51.2
>
> So my guess is that your table was corrupted by the filesystem or
> something like that. Did your system crash recently? My guess is that
> this is a filesystem problem, kernel bug or something like that.

Yep i got a crash before the first problem. But the dump run nicely
until a day it crash with this kind of error.
BTW, beetween, i put all data on a new (safe ?) database, and i dont
have any kind of crash.
Actually, do you know a way to get back a maximum of data ? I have a
particular thing : i have one dump with 13MB and other are 5MB.

I dont really understand the exact error message. That mean that on a
transaction, the DB crash (or something like that), so i have an
INSERT/UPDATE or something like that which is lost, but other data are
not corrupted ?
Or it is an index which is corrupted, so more data are corrupted too ?