Scott, Tom, Merlin: Thanks for the comments and help. It's all sorted now - the origin of the confusion was some outdated information in the JDBC driver documentation. The question arose because I was originally looking at polling from JDBC (which I know I forgot to mention), where the docs state that: "A key limitation of the JDBC driver is that it cannot receive asynchronous notifications and must poll the backend to check if any notifications were issued." http://jdbc.postgresql.org/documentation/84/listennotify.html .... and show a `SELECT 1' being issued to push any notifications. I'd assumed that was a JDBC limitation until I tested with psql and found that it, too, required some kind of client-initiated communication to see NOTIFY events, at which point I began wondering if the backend pushed them at all rather than waiting for client interaction. Hence my question. Anyway, as pointed out, psql just doesn't bother polling for notifications because it's not important for psql, but it could if it needed to - the notifications are waiting in its recieve buffer for it to notice and care. As for the JDBC driver - it turns out that the documentation is out-of-date and/or misleading. The JDBC driver *does* support reading notifications the backend has pushed to its receive buffer, and does *not* have to poll the backend or issue a statement to receive notifications. Some searching suggests that this changed in 8.0 or 8.1 . The documentation needs adjusting, so I've sent a patch to it off to the JDBC folks. -- Craig Ringer -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
