Re: Listen / Notify - what to do when the queue is full

Joachim Wieland <joe@mcknight.de>

From: Joachim Wieland <joe@mcknight.de>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, "Florian G. Pflug" <fgp@phlo.org>, Josh Berkus <josh@agliodbs.com>, pgsql-hackers@postgresql.org
Date: 2009-11-20T09:35:46Z
Lists: pgsql-hackers

Attachments

On Thu, Nov 19, 2009 at 11:04 PM, Joachim Wieland <joe@mcknight.de> wrote:
> Given your example, what I am proposing now is to stop reading from
> the queue once we see a not-yet-committed notification but once the
> queue is full, read the uncommitted notifications, effectively copying
> them over into the backend's own memory... Once the transaction
> commits and sends a signal, we can process, send and discard the
> previously copied notifications. In the above example, at some point
> one, two or all three backends would see that the queue is full and
> everybody would read the uncommitted notifications of the other one,
> copy them into the own memory and space will be freed in the queue.

Attached is the patch that implements the described modifications.


Joachim