Re: Listen / Notify rewrite

From: A(dot)M(dot) <agentm(at)themactionfaction(dot)com>
To: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Listen / Notify rewrite
Date: 2009-11-12 03:21:55
Message-ID: 631F3E12-8672-46BF-91F4-E54DB236DE33@themactionfaction.com
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On Nov 11, 2009, at 9:28 PM, Merlin Moncure wrote:

> On Wed, Nov 11, 2009 at 5:48 PM, A.M.
> <agentm(at)themactionfaction(dot)com> wrote:
>> At least with this new payload, I can set the payload to the
>> transaction ID
>> and be certain that all the notifications I sent are processed
>> (and in order
>> even!) but could you explain why the coalescing is still necessary?
>
> Christmas comes early this year! :-).
>
> three reasons:
> *) it works that way now...a lot of people use this feature for all
> kinds of subtle things and the behavior chould change as little as
> possible
> *) legacy issues aside, I think it's generally better behavior (how
> many times do you need to be tapped on the shoulder?)
> *) since you can trivially differentiate it (using xid, sequence,
> etc), what's the fuss?

Except for the fact that the number of times a notification occurred
may be valuable information.

I thought of a compromise: add the number of times a notification was
generated (coalesced count+1) to the callback data. That would
satisfy any backwards compatibility concerns and my use case too!

Cheers,
M

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