TIMESTAMPTZ is stored including the timezone. DatabaseTable connector doesn't work with timezone directly, but the value is automatically converted to midPoint local timezone. Therefore, you always work with local timezone in mappings and it will be automatically stored correctly in the database.
PostgreSQL server might be configured to close the idle connection after several minutes. That will raise following exception in the DatabaseTable connector "DB error: org.postgresql.util.PSQLException(An I/O error occurred while sending to the backend.)->;java.net.SocketException(Connection reset)". Solution for this problem is configure jdbc driver to send keepalive packets by adding "keepalives=1" and "keepalives_idle=XXX" (XXX is number of seconds after which keepalive packet will be sent) to jdbcUrlTemplate. For example: