"Thomas F.O'Connell" <tfo@monsterlabs.com> writes:
> As for the bad data on disk, I've got a backup, but how severe are we
> talking? By not trusting it, do you mean that it could be flagrantly
> wrong (i.e., truly corrupted; bad data), or just out of sync with
> whatever writes were last occurring?
The high clog numbers you were quoting suggest completely-trashed
transaction ID fields (I'm assuming that the files actually present in
pg_clog have numbers nowhere near that). I've only seen that happen in
the context of completely-trashed disk pages. You could possibly do
some investigation for yourself using pg_filedump.
regards, tom lane