Re: notification payloads

Ühel kenal päeval, E, 2007-03-26 kell 11:30, kirjutas Andrew Dunstan:
> This feature (ability to add a message payload to a NOTIFY) is on the
> TODO list and I had undertaken to implement it. However, pressure of
> other work has conspired to make that difficult, and Abhijit Menon-Sen
> recently very kindly offered to help out.
>
> Therer was some discussion of implementation late last year here:
> http://groups.google.com/group/pgsql.hackers/browse_frm/thread/e63a5ac43e2508ce/ce47016235bd5a62?tvc=1&q=notify+payload&hl=en#ce47016235bd5a62
>
> However, in various pieces of off-list discussion it appears that there
> is some opposition either to the design or to the feature itself. What
> is more, there will clearly be vigorous opposition to any implementation
> which does NOT remove the use of pg_listener (which I understand and I
> think largely agree with).
>
> So, before an investment of any more time is made by either Abhijit or
> myself, I would like to get confirmation that a) there is broad
> agreement on the desirability of the feature and b) that there is broad
> agreement on the general design (i.e. to use a circular buffer in shared
> memory, of configurable size, to hold the outstanding message queue).
> Please speak up or forever ....

I find the feature very useful, and have even done some preliminary
design work for shared memory implementation, where each listener is
required to copy data to its own privat memory ASAP and notifier waits
in case there is not enough room in shared memory buffer.

Alas, I have lost my design 3 a4 pages of design notes for organising
things in fixed-size buffer, but the basic operation data-wise sould be
as in attached sql file.

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