Re: Corrupt index

This pattern of misbehavior does occur repeatedly for
me.

I don't know if this may have something to do with it,
but we do backup the data every night using VERITAS
Backup Exec. We are not restoring anything, though
(the data is backed up to tape). The VERITAS software
runs on Windows, but there is an agent that runs on
our Linux box where the PostgreSQL data is stored. I
should also mention that the backup is running while
the database is being modified (we modify the database
24/7).

There is another unexpected behavior that I noticed
for the first time this morning (so I am not sure if
it's recurring, related or relevant). The database
"blinked" in the sense that all database connections
were lost - but new connections could be obtained
immediately after the "blink". The error message that
I got said something about possible "corrupted shared
memory" and I guess the shutting down of the
connections was a precautionary measure.

I hope this additional information helps.

--- Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Amir Becher <abecher@yahoo.com> writes:
> > Here is an example of the misbehavior that I am
> > seeing:
> > [snip]
> > The main point is that "column_a" is the wrong
> number.
>
> Hmm.  This looks like you must have an index entry
> pointing at the wrong
> heap tuple.  Which is not something we hear of
> regularly, and certainly
> not an error that I'd expect to see appearing in
> isolation.
>
> You didn't say in so many words, but should I take
> it that (a) this
> pattern of misbehavior (wrong row returned) occurs
> repeatedly for you,
> and (b) there are no other signs of problems
> (backend unexpectedly
> quits, strange error messages, that sort of thing)?
>
> I can't really think of any plausible mechanism for
> this to happen,
> except for the index and table files getting out of
> sync somehow.
> Are you doing anything that operates directly on the
> database files
> (for example, doing backup/restore with cp or tar or
> some such)?
>
>             regards, tom lane

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