Detecting database corruption

My company is developing a PostgreSQL 7.4 application. We don't want
our customers to have to manage the database, so we're automating as
much maintenance as possible. If the database ever becomes corrupt,
we have procedures for restoring the database from backup data.
The question we've been wondering about is how to detect a corrupt
database. False positives are acceptable (database isn't really
corrupt but we think it is); false negatives are not, (database
is corrupt but we can't tell).

- Are any cases of corruption detected in the normal operation of
PostgreSQL?

- If there are, then how are applications notified when corruption
is detected?

- What symptoms should prompt us to suspect and check for corruption?

- Are there any tools we can run to determine whether a database is
corrupt?

Jack Orenstein