Re: Sending notifications from the master to the standby

From: Peter Geoghegan <peter(at)2ndquadrant(dot)com>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Sending notifications from the master to the standby
Date: 2012-01-12 00:08:10
Message-ID: CAEYLb_XQnZFuZqDTeuzohqMj8PyUnxy59bOqN+fCmL7Bw+sSnA@mail.gmail.com
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On 11 January 2012 23:51, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>
>> Yeah, upthread Simon pointed out that propagating notifies would be
>> useful for flushing caches in applications that watch the database in a
>> read-only fashion.  I grant that such a use-case is technically possible
>> within the limitations of a slave server; I'm just dubious that it's a
>> sufficiently attractive use-case to justify the complexity and future
>> maintenance costs of the sort of designs we are talking about.  Or in
>> other words: so far, cache invalidation is not the "first" use-case,
>> it's the ONLY POSSIBLE use-case.  That's not useful enough.
>
> Well, cache invalidation is a pretty common task; probably more than 50%
> of all database applications need to do it.

I agree that it would be nice to support this type of cache
invalidation - without commenting on the implementation, I think that
the concept is very useful, and of immediate benefit to a significant
number of people.

--
Peter Geoghegan       http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training and Services

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