Re: Unfamous 'could not read block ... in file "...": read only 0 of 8192 bytes' again

On Monday, February 20, 2012 5:32:01 pm Tom Lane wrote:
> Maxim Boguk <maxim(dot)boguk(at)gmail(dot)com> writes:
> > One of servers under my support 2 days ago produced the next error:
> > ERROR: could not read block 135 in file "base/16404/118881486": read
> > only 0 of 8192 bytes
> > ...
> > What I see in file system:
> > hh=# SELECT relfilenode from pg_class where
> > relname='agency_statistics_old';
> >
> > relfilenode
> >
> > -------------
> >
> > 118881486
> >
> > postgres(at)db10:~/tmp$ ls -la
> > /var/lib/postgresql/9.0/main/base/16404/118881486
> > -rw------- 1 postgres postgres 0 2012-02-20 12:04
> > /var/lib/postgresql/9.0/main/base/16404/118881486
> >
> > So table file size zero bytes (seems autovacuum truncated that table to 0
> > bytes).
>
> Hmmm .... something did, but I see no clear evidence that it was
> autovacuum.
>
> Do you know why the mod date on the file is 2012-02-20 12:04? That's
> more than two days after the error in your logs, so it's not clear to me
> that the current state of the file tells us much about what happened on
> the 17th. If autovacuum had truncated the table then, and the table
> wasn't touched otherwise, the file mod date shouldn't have increased.

If I am following correctly that is due to this:

"I recreated table from scratch and keep the damaged table under another
name (through alter table agency_statistics rename to
agency_statistics_old).
So I have files to dig into."

>
> regards, tom lane

--
Adrian Klaver
adrian(dot)klaver(at)gmail(dot)com