Re: index corruption?

On Monday March 31 2003 3:54, Tom Lane wrote:
> "Ed L." <pgsql@bluepolka.net> writes:
> >> I am seeing this same problem on two separate machines, one brand new,
> >> one older.  Not sure yet what is causing it, but seems pretty unlikely
> >> that it is hardware-related.
> >
> > I am dabbling for the first time with a (crashing) C trigger, so that
> > may be the culprit here.
>
> Could well be, although past experience has been that crashes in C code
> seldom lead directly to disk corruption.  (First, the bogus code has to
> overwrite a shared disk buffer.  If you follow what I consider the
> better path of not making your shared buffers a large fraction of the
> address space, the odds of a wild store happening to hit a disk buffer
> aren't high.  Second, once it's corrupted a shared buffer, it has to
> contrive to cause that buffer to get written out before the core dump
> occurs --- in most cases, the fact that the postmaster abandons the
> contents of shared memory after a backend crash protects us from this
> kind of failure.)
>
> When you find the problem, please take note of whether there's something
> involved that increases the chances of corruption getting to disk.  We
> might want to try to do something about it ...

It is definitely due to some rogue trigger code.  Not sure what exactly, but
if I remove a certain code segment the problem disappears.

Ed