To: Igor Shevchenko <igor@carcass.ath.cx>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: libpq/async notifications 
In-reply-to: <200310111220.25923.igor@carcass.ath.cx> 
References: <200310111220.25923.igor@carcass.ath.cx>
Comments: In-reply-to Igor Shevchenko <igor@carcass.ath.cx>
	message dated "Sat, 11 Oct 2003 12:20:25 +0300"
Date: Tue, 14 Oct 2003 12:10:21 -0400
Message-ID: <9884.1066147821@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Igor Shevchenko <igor@carcass.ath.cx> writes:
> Is there a way to only check if there's any pending async notifications ?
> I've found only PQnotifies(..) but it also removes the first notification from 
> the list.
> A function for only checking this can be used in a gui app to setup async 
> notifications processing so it happens only after an app reaches it's main 
> loop (which is a good idea since it won't happen in the middle of another 
> app's handler function which happens to use pgsql database interface).
> Currently I have to check for notifications with PQnotifies every time my app 
> returns to the main loop after using any of PGexec, etc, which is not very 
> efficient.

"Not very efficient"?  This seems like a very weak argument.  The actual
cost of running the function is no different from PQnotifies in the case
where no notify event is found; and in the case where one is found, it'd
be slower because you'd then have to call PQnotifies anyway to remove
the item from the list.

Yes, I know the function is only five lines, but there are also
documentation and other maintenance costs to consider anytime we add
something to libpq's API.  I don't think you've made enough of a case
for it.

			regards, tom lane