Re: proposal: make NOTIFY list de-duplication optional

On Sun, Feb 7, 2016 at 4:37 PM, Vik Fearing <vik(at)2ndquadrant(dot)fr> wrote:

>>> There is also no mention in the documentation about what happens if I do:
>>>
>>> NOTIFY ALL chan, 'msg';
>>> NOTIFY ALL chan, 'msg';
>>> NOTIFY DISTINCT chan, 'msg';
>>> NOTIFY ALL chan, 'msg';
>>>
>>> Without testing, I'd say I'd get two messages, but it should be
>>> explicitly mentioned somewhere.
>>
>> If it's four separate transactions, LISTEN'er should get four.
>
> The question was for one transaction, I should have been clearer about that.
>
>> If it's in one transaction, LISTEN'er should get three.
>
> This is surprising to me, I would think it would get only two. What is
> your rationale for three?
>

It is a single transaction, but four separate commands.

>>> NOTIFY ALL chan, 'msg';
-- send the message, save in the list/hash
>>> NOTIFY ALL chan, 'msg';
-- ALL was specified, send the message even if it is on the list/hash
>>> NOTIFY DISTINCT chan, 'msg';
-- default mode, skip message because it's in the list/hash
>>> NOTIFY ALL chan, 'msg';
-- ALL was specified, send the message even if it is hashed/saved