creimer@brturbo.com.br writes:
> And why this happens only with 8.0 and 8.1 and not with the 7.4?
8.0 and 8.1 are vulnerable to this behavior because of conflicts for
access to pg_subtrans (which didn't exist in 7.4). The problem occurs
when you have old open transactions, causing the window over which
pg_subtrans must be accessed to become much wider than normal.
8.2 should eliminate or at least alleviate the issue, but in the
meantime see if you can get your applications to not sit on open
transactions.
regards, tom lane