On 02/21/2017 02:19 PM, Rob Brucks wrote:
I did find a post a while back saying they were discarded, but I wanted
to double-check.
I performed some tests to see if listens worked AFTER the notify was
issued, they were not. This leads me to believe that the messages are
discarded when a listen does not yet exist.
Seems the thing to do would be to monitor the size of :
$PG_DATA/pg_notify/
--Rob
*From: *"David G. Johnston" <[email protected]>
*Date: *Tuesday, February 21, 2017 at 3:38 PM
*To: *Adrian Klaver <[email protected]>
*Cc: *Rob Brucks <[email protected]>,
"[email protected]" <[email protected]>
*Subject: *Re: [GENERAL] NOTIFY command impact
On Tue, Feb 21, 2017 at 2:17 PM, Adrian Klaver
<[email protected] <mailto:[email protected]>> wrote:
On 02/21/2017 01:07 PM, Rob Brucks wrote:
Do you see any long-term problems with constantly issuing "NOTIFY"
commands every 30 seconds without an associated "LISTEN" command?
Depending on how long 'long term' is:
https://www.postgresql.org/docs/9.6/static/sql-notify.html
"There is a queue that holds notifications that have been sent but
not yet processed by all listening sessions
Its not clear in the OP that this is the case (it seems to be) but the
documentation is non-specific as to what happens when "# of listeners" =
0; I suspect that said messages are created and then immediately
discarded - though apparently they do make it over to the standby server
too - and likely also immediately discarded there as well.
David J.
--
Adrian Klaver
[email protected]
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