Hmm, that makes it sound like a plain old data-corruption problem, ie,
trashed xmin or xmax in some tuple header. Can you do a "select
count(*)" from this table without getting the error?
no, select count(*) fails around 25 millions rows.
PostgreSQL 8.1RC1 on x86_64-unknown-linux-gnu, compiled by GCC gcc
(GCC) 4.0.1
[ raised eyebrow... ] You're keeping important data in an RC version
that you've not updated for more than a year? Your faith in Postgres'
code quality is touching, but I'd counsel getting onto a more recent
release.
regards, tom lane