Howdy all, NOTE: Grey-beard coder, pgsql newbie. All info/tips/suggestions welcome!
I have a use-case where I’d like to LISTEN for all NOTIFY channels. Right now I simply issue a LISTEN for every channel name of interest, but in production the channels will number in the low thousands. The current implementation uses a linked list, and a linear probe through the list of desired channels which will always return true becomes quite expensive at this scale. I have a work-around available by creating the “ALL” channel and making the payload include the actual channel name, but this has a few of drawbacks: * it does not play nice with clients that actually want a small subset of channels; * it requires code modification at every NOTIFY; * it requires extra code on the client side. The work-around subjects the developer (me :-) to significant risk of foot-gun disease, so I'd like to propose a 'LISTEN *' equivalent to 'UNLISTEN *'. The implementation in src/backend/commands/async.c seems straightforward enough, but it feels prudent to select a syntax that doesn't make some kind of actual pattern matching syntactically ugly in the future. Choosing 'LISTEN *' has a nice symmetry with 'UNLISTEN *', but I don't have enough SQL chops to know if it cause problems. If anyone has a better work-around, please speak up! If not, and we can come to some resolution on a future-resistant syntax, I'd happily start working up a patch set. Thanks, -- Trey Boudreau
