On Mon, Jan 26, 2015 at 3:42 PM, Dave Cramer <pg@fastcrypt.com> wrote:
Pawel,
Have a look at org/postgresql/test/jdbc2/NotifyTest.java for exactly what you proposed. As for when it gets notified, I do not know how you would tell as the spec does not provide this functionality (AFAIK)
AFAIK too JDBC doesn't. But IMHO, a meaningful (short of polling on a timer, which makes it either CPU intensive, or delayed) LISTEN/NOTIFY application is not particularly possible without a mechanism that will somehow call into the app to notify that a notification is ready.
Also, 'raise notice' from a statement is treated as SQLWarning by the driver, not a notification. I've poked around the source and it's actually quite tricky. Warnings that come out anything but the result response are attached directly to the connection. But the result warnings are sent through some cumbersome (to me :) ) chain of handlers.
I've put together this patch (over 9.1-902, which is just what I currently use), if anybody's interested: http://pastebin.com/KftdtdNq ,but:
- it uses JDK6 stuff
- has effect of copying all statements/resultset warnings into connection warnings
Also, thank you, Kevin. May be I'll try out the NG driver once I upgrade the project JDK :)
I've seen that :) May be I'm missing something, but that's not asynchronous. I need to wait until statement finishes before calling those getWarnings() methods. May be I can call them from another thread (at least on Connection/Statement object) as the SQL is being processed, and they will return current messages, but I'm not sure when to - i.e. how do I know when a new message has been made available.
Is it possible to get output of raise notice statements as produced by a PL function, as the function is being executed? And if yes, what version was that introduced in?
