On Sat, May 4, 2019 at 1:49 PM Igal Sapir <igal@lucee.org> wrote:
<snip/>
> 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
Polling is much less efficient than event handling and I'm sure that there's a major performance hit with that.
Isn't that addressed here?:
// If this thread is the only one that uses the connection, a timeout can be used to // receive notifications immediately: // org.postgresql.PGNotification notifications[] = pgconn.getNotifications(10000);
It "helps", but it's still not the same as keeping the connection open and receiving messages in real time.
But it is the same as that. It keeps the connection open, and receives the messages in real time. It blocks either until it gets a NOTIFY, or for 10 seconds, whichever occurs first. You can use 0 to block forever until a NOTIFY arrives. Maybe you didn't remove the sleep a few lines further down? Or is there some other problem here?
I didn't try it out, but I know from experience with other systems that long polling is not as efficient as asynchronous events over an open socket. For example, Comet vs. WebSockets in web servers.
The only way to find out how big, or small, the impact is, is to benchmark both implementations, but I have no doubt that the open socket will be more efficient.