Re: Strange update behaviour

ProfiVPS Support <support@profivps.hu> writes:
>    I hope everything is there to enable testing.

Thanks for sending a test case!  But I think this is a logic bug
in your function.  There are several updates of app_devices in
that function.  Adding some "raise notice" commands to track the
logic flow, I see that the given case results in

# SELECT collectd_insert(CURRENT_TIMESTAMP,
'DE:AD:A7:14:69:9210.123.4.12', 'ruckusphp', '', 'pstates_enabled',
'state', '{et}', '{0}', '{1}');
NOTICE:  first update happening
NOTICE:  fourth update happening
 collectd_insert
-----------------

(1 row)

So it is first doing

                UPDATE app_devices SET device_state=1, device_changets=NOW(), device_updatets=NOW()
                       WHERE device_id= dev_id;

and then later doing the UPDATE you showed.  But at that point,
device_state is already 1 so neither of the device_alertstate or
device_changets updates change the column's value.  It's unobvious
that the device_changets update is a no-op because the first
UPDATE already set it to the same new value.

            regards, tom lane