David, Thanks for your response!
/s/jr Consultant Concerto GR Mobile: 612.208.6601 Concerto - a composition for orchestra and a soloist > On 28Aug, 2017, at 5:36 PM, David G. Johnston <david.g.johns...@gmail.com> > wrote: > > On Mon, Aug 28, 2017 at 1:28 PM, Jerry Regan > <jerry.re...@concertoglobalresources.com > <mailto:jerry.re...@concertoglobalresources.com>> wrote: > My concern is how, after LISTENing in psql, I can tell it what to do when the > NOTItFY is received. > > As far as I am aware you cannot. The docs for psql, and its feature set, > with respect to LISTEN, are minimal and basically say psql will print out > notifications to stdout (this I'm forced to assume or read the code) and will > poll for notifications whenever it sends a query to the server. I’ve tested using LISTEN and NOTIFY in psql. First I issued the LISTEN, then when my prompt came back, issued the NOTIFY from psql. This is an example from the psql docs, I believe. In any case, that the NOTIFY had occurred was reported in the psql window. > > https://www.postgresql.org/docs/current/static/app-psql.html > <https://www.postgresql.org/docs/current/static/app-psql.html> > > "Whenever a command is executed, psql also polls for asynchronous > notification events generated by LISTEN and NOTIFY." > > I suspect the feature request would be something like: > > \set NOTIFY_PROGRAM './process-notify-request.bash' (or an equivalent > meta-command) Since the database would issue the NOTIFY, not sure \set would be used, but otherwise, yes. Or, I may just send information about the inserted row. It depends on what psql would need. > > And psql would invoke said program and pass the content of the notification > payload to it via stdin. I’d rather have psql know the program name to invoke, but since I don’t really know how all this works, I may have no choice. > > Given what we allow for "\copy" I don't see any technical or conceptual > problems with such a feature. Just needs someone to be its primary author. > > David J.
