Обсуждение: Could not read block error question

Hello

One question about blocks in PG. I got an error "Could not read block
<no.> of relation...." it appeared to be in pg_trigger but the thing
is that the block number was 110 and the file has only 67 pages. So
the question is how is it possible?
--
Łukasz Brodziak

Lukasz Brodziak <lukasz.brodziak@gmail.com> wrote:

> I got an error "Could not read block <no.> of relation...." it
> appeared to be in pg_trigger

If you'd pasted in the message as it appeared, we wouldn't need to
guess whether you're right.

> the block number was 110 and the file has only 67 pages. So the
> question is how is it possible?

That could be, if your reading of things is right, database
corruption.  Before you do anything else, shutdown the database
server and make a copy of the data directory and all its
subdirectories.  (Don't try to pick one database or otherwise pick
and choose files.)  Save that backup until you've recovered from the
problem and things have been stable for at least a few weeks.

Next, read this page and repost with more information:

http://wiki.postgresql.org/wiki/Guide_to_reporting_problems

So far you haven't given us much to work with.

-Kevin

I would provide all the needed information if I only had them. The
thing is it happened on one of our client's machine and all he did was
reporting the problem without providing us the data folder. So I asked
the question just to know whether it is possible to read from a higher
block number than the highest physical number. Thank You for Your
attention.

2010/9/28 Kevin Grittner <Kevin.Grittner@wicourts.gov>:
> Lukasz Brodziak <lukasz.brodziak@gmail.com> wrote:
>
>> I got an error "Could not read block <no.> of relation...." it
>> appeared to be in pg_trigger
>
> If you'd pasted in the message as it appeared, we wouldn't need to
> guess whether you're right.
>
>> the block number was 110 and the file has only 67 pages. So the
>> question is how is it possible?
>
> That could be, if your reading of things is right, database
> corruption.  Before you do anything else, shutdown the database
> server and make a copy of the data directory and all its
> subdirectories.  (Don't try to pick one database or otherwise pick
> and choose files.)  Save that backup until you've recovered from the
> problem and things have been stable for at least a few weeks.
>
> Next, read this page and repost with more information:
>
> http://wiki.postgresql.org/wiki/Guide_to_reporting_problems
>
> So far you haven't given us much to work with.
>
> -Kevin
>
> --
> Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-admin
>



--
Łukasz Brodziak
II MU Bioinformatyka

Lukasz Brodziak <lukasz.brodziak@gmail.com> writes:
> One question about blocks in PG. I got an error "Could not read block
> <no.> of relation...." it appeared to be in pg_trigger but the thing
> is that the block number was 110 and the file has only 67 pages. So
> the question is how is it possible?

Well, that's why it failed to read the block ;-).  The real question is
why was it trying to read a block that doesn't exist in the table.
I'd bet on a corrupt index myself, so try reindexing.

            regards, tom lane