Subject: Re: Sync Rep for 2011CF1
From: Simon Riggs <simon@2ndQuadrant.com>
To: Magnus Hagander <magnus@hagander.net>
Cc: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>,
	pgsql-hackers@postgresql.org
In-Reply-To: <AANLkTimSWJ-W8V3us5rFLHFjAC=bwcLikt4ERfXjH8St@mail.gmail.com>
References: <1295127631.3282.100.camel@ebony>
	<4D397FE4.2020709@enterprisedb.com> <1295616270.1803.10799.camel@ebony>
	<AANLkTimSWJ-W8V3us5rFLHFjAC=bwcLikt4ERfXjH8St@mail.gmail.com>
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Date: Fri, 21 Jan 2011 17:00:41 +0000
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On Fri, 2011-01-21 at 14:34 +0100, Magnus Hagander wrote:
> On Fri, Jan 21, 2011 at 14:24, Simon Riggs <simon@2ndquadrant.com> wrote:
> > On Fri, 2011-01-21 at 14:45 +0200, Heikki Linnakangas wrote:
> >> * it seems like overkill to not let clients to even connect when
> >> allow_standalone_primary=off and no synchronous standbys are available.
> >> What if you just want to run a read-only query?
> >
> > That's what Aidan requested, I agreed and so its there. You're using
> > sync rep because of writes, so you have a read-write app. If you allow
> > connections then half of the app will work, half will not. Half-working
> > isn't very useful, as Aidan eloquently explained. If your app is all
> > read-only you wouldn't be using sync rep anyway. That's the argument,
> > but I've not got especially strong feelings it has to be this way.
> >
> > Perhaps discuss that on a separate thread? See what everyone thinks?
> 
> I'll respond here once, and we'll see if more people want to comment
> then we can move it :-)
> 
> Doesn't this make a pretty strange assumption - namely that you have a
> single application? We support multiple databases, and multiple users,
> and multiple pretty much anything - in most cases, people deploy
> multiple apps. (They may well be part of the same "solution" or
> whatever you want to call it, but parts may well be readonly - like a
> reporting app, or even just a monitoring client)

There are various problems whatever we do. If we don't like one way, we
must balance that by judging what happens if we do things the other way.

-- 
 Simon Riggs           http://www.2ndQuadrant.com/books/
 PostgreSQL Development, 24x7 Support, Training and Services