| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Joachim Wieland <joe(at)mcknight(dot)de>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Sending notifications from the master to the standby |
| Date: | 2012-01-11 09:09:38 |
| Message-ID: | CA+U5nMKL+0fVmh96vfKwXKkhMLkospnGP1_C-giR_VwOLgsF_Q@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Jan 11, 2012 at 4:33 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> BTW ... it occurs to me to ask whether we really have a solid use-case
> for having listeners attached to slave servers. I have personally never
> seen an application for LISTEN/NOTIFY in which the listeners were
> entirely read-only. Even if there are one or two cases out there, it's
> not clear to me that supporting it is worth the extra complexity that
> seems to be needed.
The idea is to support external caches that re-read the data when it changes.
If we can do that from the standby then we offload from the master.
Yes, there are other applications for LISTEN/NOTIFY and we wouldn't be
able to support them all with this.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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