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* Unexpected Backend PID reported by Notification
@ 2024-06-11 15:05 Dominique Devienne <[email protected]>
0 siblings, 1 reply; 3+ messages in thread
From: Dominique Devienne @ 2024-06-11 15:05 UTC (permalink / raw)
To: [email protected]
Hi. I have a unit test using a single connection, that simulates a
client interacting with a server via a PostgreSQL "queue", i.e. a
non-writable table with SECURITY DEFINER procedures to mediate writes
to that table, with those PROC-initiated updates triggering
pg_notify() messages (via an UPDATE trigger).
The test is passing, I get all the side-effects and notifications I
expect. BUT...
For some reason, the backend_pid reported on the notification object
itself (i.e. PGnotify::be_pid),
is different from the one reported for the (sole) connection the unit
test is using (PQbackendPID()).
How can that be?
Are Stored PROCs running in a different backend?
Are Triggers running in a different backend?
Any doc pointers to explain this behavior?
Thanks. --DD
PS: v14 server on RedHat; v16 libpq on Windows
PPS: Below's a snippet of my test code, which shows actual PID values:
auto perreq_notif = c.notification();
BOOST_REQUIRE(perreq_notif);
BOOST_CHECK_EQUAL(perreq_notif.channel(), req.channel());
/*
** In fact I get perreq_notif.backend_pid() == N + c.backend_pid() !!!
** Is the fact the pg_notify() is done from a trigger the reason???
** e.g. [4053957 != 4053955]
BOOST_CHECK_EQUAL(perreq_notif.backend_pid(), c.backend_pid());
*/
BOOST_CHECK_EQUAL(perreq_notif.payload(), "...");
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Unexpected Backend PID reported by Notification
@ 2024-06-11 15:29 David G. Johnston <[email protected]>
parent: Dominique Devienne <[email protected]>
0 siblings, 1 reply; 3+ messages in thread
From: David G. Johnston @ 2024-06-11 15:29 UTC (permalink / raw)
To: Dominique Devienne <[email protected]>; +Cc: [email protected] <[email protected]>
On Tuesday, June 11, 2024, Dominique Devienne <[email protected]> wrote:
>
> Are Stored PROCs running in a different backend?
> Are Triggers running in a different backend?
>
No to both. Whatever backend the SQL to invoke those was sent on is the
backend that executes them.
David J.
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Unexpected Backend PID reported by Notification
@ 2024-06-12 06:53 Dominique Devienne <[email protected]>
parent: David G. Johnston <[email protected]>
0 siblings, 0 replies; 3+ messages in thread
From: Dominique Devienne @ 2024-06-12 06:53 UTC (permalink / raw)
To: David G. Johnston <[email protected]>; +Cc: [email protected] <[email protected]>
On Tue, Jun 11, 2024 at 5:29 PM David G. Johnston
<[email protected]> wrote:
> On Tuesday, June 11, 2024, Dominique Devienne <[email protected]> wrote:
>> Are Stored PROCs running in a different backend?
>> Are Triggers running in a different backend?
> No to both. Whatever backend the SQL to invoke those was sent on is the backend that executes them.
Thanks for confirming David (and Adrian). I indeed had two connections
after all. User error. Sorry for the noise. --DD
^ permalink raw reply [nested|flat] 3+ messages in thread
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2024-06-11 15:05 Unexpected Backend PID reported by Notification Dominique Devienne <[email protected]>
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