"Andrus" <kobruleht2(at)hot(dot)ee> writes:
> I have table in 8.1.4 which tracks users logged into db
There have been a number of index-corruption bugs fixed since 8.1.4 ...
In particular, if it's possible that any of these clients abort before
committing these insertions, the vacuum race condition bug fixed in
8.1.10 is a pretty likely candidate for your problem.
regards, tom lane