From: Jim C. Nasby <jnasby@pervasive.com>
To: Mark Kirkwood <markir@paradise.net.nz>
Cc: Craig A. James <cjames@modgraph-usa.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Overriding the optimizer
Date: Fri, 16 Dec 2005 16:45:12 -0600
Message-ID: <20051216224512.GX53809@pervasive.com> (raw)
In-Reply-To: <43A231AA.9070708@paradise.net.nz>
References: <200512141603.52583.blargity@gmail.com>
<7484.1134600423@sss.pgh.pa.us>
<1134629567.14248.27.camel@firebolt>
<200512150148.16125.blargity@gmail.com>
<1134644526.14248.60.camel@firebolt>
<43A1C40D.8040006@paradise.net.nz>
<43A1F6DB.3080805@modgraph-usa.com>
<43A226E7.7040508@paradise.net.nz>
<43A22BE3.6020103@modgraph-usa.com>
<43A231AA.9070708@paradise.net.nz>
On Fri, Dec 16, 2005 at 04:16:58PM +1300, Mark Kirkwood wrote:
> Craig A. James wrote:
>
> >
> >What would be cool would be some way the developer could alter the plan,
> >but they way of doing so would strongly encourage the developer to send
> >the information to this mailing list. Postgres would essentially say,
> >"Ok, you can do that, but we want to know why!"
> >
>
> Yeah it would - an implementation I have seen that I like is where the
> developer can supply the *entire* execution plan with a query. This is
> complex enough to make casual use unlikely :-), but provides the ability
> to try out other plans, and also fix that vital query that must run
> today.....
Being able to specify an exact plan would also provide for query plan
stability; something that is critically important in certain
applications. If you have to meet a specific response time requirement
for a query, you can't afford to have the optimizer suddenly decide that
some other plan might be faster when in fact it's much slower.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, markir@paradise.net.nz, cjames@modgraph-usa.com
Subject: Re: Overriding the optimizer
In-Reply-To: <20051216224512.GX53809@pervasive.com>
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