Re: Corruption of files in PostgreSQL

Paolo Bizzarri,

I am also using postgresql in my application and also facing file object
corruption problem.

I already discussed several times with Richard Huxton, and ended without any
clue.

Here I am briefing my problem, see if u find any clue about it.
I am storing/retrieving my file in postgresql using lo_export() and
lo_import() api.

after few weeks (as application is being used - number of file objects in
database also grows) my file object gets corrupted. And I have no clue about
which causes this problem.

I confirmed the file corruption by the following query,

sfrs2=> select loid, pageno, length(data) from pg_largeobject where loid =
101177 and pageno = 630;
loid | pageno | length
--------+--------+--------
101177 | 630 | 181
(1 row)

But actually the result of the above query before corruption(ie, immediately
after file object added to table)

fasp_test=> select loid, pageno, length(data) from pg_largeobject where loid
= 106310 and pageno = 630;
loid | pageno | length
--------+--------+--------
106310 | 630 | 205
(1 row)

I uploaded same file in both(sfrs2, fasp_test) databases. The first one
result is after the corruption. and the later is before corruption.

You also confirm you problem like this. And I strongly believe that, there
is some bug in PostgreSQL.

Kindly don't forget to alert me once u find solution/cause.

Regards,
Purusothaman A

On 5/30/07, Paolo Bizzarri <pibizza(at)gmail(dot)com> wrote:
>
> On 5/30/07, Richard Huxton <dev(at)archonet(dot)com> wrote:
> > Paolo Bizzarri wrote:
> > > We use postgres as a backend, and we are experimenting some corruption
> > > problems on openoffice files.
> >
> > 1. How are you storing these files?
>
> Files are stored as large objects. They are written with an lo_write
> and its contents is passed as a Binary object.
>
> > 2. What is the nature of the corruption?
>
> Apparently, files get truncated.
>
> > > As our application is rather complex (it includes Zope as an
> > > application server, OpenOffice as a document server and as a client)
> > > we need some info on how to check that we are interacting correctly
> > > with Postgres.
> >
> > Shouldn't matter.
>
> I hope so...
>
> > > We are currently using:
> > >
> > > - PostgreSQL 7.4.8;
> >
> > Well, you need to upgrade this - version 7.4.17 is the latest in the 7.4
> > series. You are missing 9 separate batches of bug and security fixes.
>
> Ok. We will upgrade and see if this can help solve the problem.
>
> >
> > > - pyscopg 1.1.11;
> > > - Zope 2.7.x;
> > > - Openoffice 2.2.
> >
> > None of this should matter really, unless there's some subtle bug in
> > psycopg causing corruption of data in-transit.
> >
> > Let's get some details on the two questions above and see if there's a
> > pattern to your problems.
>
> Ok. Thank you.
>
> Paolo Bizzarri
> Icube S.r.l.
>
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