Auditing and Postgres 7.3

Hi all,

I've been thinking implementing auditing for Postgres 7.3 and wanted to
see if anyone had any thoughts about it.

Auditing would allow a user to log queries executed upon different
'schema' objects - I use the loose sense of the word here. The user would
be able to define the type of query - insert, delete, etc - as well as
choose to log only those queries which were successful or otherwise.

The superuser would be able to audit unprivileged users. Unprivileged
users would only be able to produce an audit trail upon objects which
he/she owns or has been granted audit privileges to.

The audit trail would be written either to a new internal system table,
pg_audit, or optionally a file on the file system. I imagine that an
external program would also be needed to read/dump the audit trail.

So what would an audit trail consist of?

timestamp
query type
query
query result (successful|unsuccessful)
audit object oid

I haven't really thought about this too hard just yet but thought I'd see
if people considered this to be a useful addition to Postgres or not, or
if I was going about this the wrong way.

Gavin