Re: proposal: make NOTIFY list de-duplication optional

On Sun, Feb 7, 2016 at 11:54 AM, Vik Fearing <vik(at)2ndquadrant(dot)fr> wrote:
> On 02/07/2016 03:42 AM, Filip Rembiałkowski wrote:

> You left the duplicate behavior with subtransactions, but didn't mention
> it in the documentation. If I do NOTIFY DISTINCT chan, 'msg'; then I
> expect only distinct notifications but I'll get duplicates if I'm in a
> subtransaction. Either the documentation or the code needs to be fixed.

agreed

>
> I seem to remember some discussion about not using DEFAULT parameters in
> system functions so you should leave the old function alone and create a
> new function with your use_all parameter. I don't recall the exact
> reason why so hopefully someone else will enlighten me.

I'm quite new to this; how do I pinpoint proper OID for a new catalog
object (function, in this case)?
Is there a better way than browsing fmgr files and guessing next available oid?

>
> 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.
If it's in one transaction, LISTEN'er should get three.

> --
> Vik Fearing +33 6 46 75 15 36
> http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support