This is the initial version of an auditing module for Postgres.

It collects audit events from various sources and logs them in CSV format
including a timestamp, user information, details of objects affected (if any),
and the fully-qualified command text (whenever available).

All DDL, DML (including SELECT), and utility commands are supported. These
are categorised as described below, and audit logging for each group of
commands may be enabled or disabled by the superuser. Once enabled, however,
audit logging may not be disabled by a user.