From: Craig A. James <cjames@modgraph-usa.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Overriding the optimizer
Date: Thu, 15 Dec 2005 21:41:06 -0800
Message-ID: <43A25372.8090706@modgraph-usa.com> (raw)
In-Reply-To: <20051216052025.GB691@filer>
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>
<20051216052025.GB691@filer>
Kevin Brown wrote:
>>Hints are dangerous, and I consider them a last resort.
>
> If you consider them a last resort, then why do you consider them to
> be a better alternative than a workaround such as turning off
> enable_seqscan, when all the other tradeoffs are considered?
If I understand enable_seqscan, it's an all-or-nothing affair. Turning it off turns it off for the whole database, right? The same is true of all of the planner-tuning parameters in the postgres conf file. Since the optimizer does a good job most of the time, I'd hate to change a global setting like this -- what else would be affected? I could try this, but it would make me nervous to alter the whole system to fix one particular query.
> If your argument is that planner hints would give you finer grained
> control, then the question is whether you'd rather the developers
> spend their time implementing planner hints or improving the planner.
I agree 100% -- I'd much prefer a better planner. But when it comes down to a do-or-die situation, you need a hack, some sort of workaround, to get you working *today*.
Regards,
Craig
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To: pgsql-performance@postgresql.org
Cc: cjames@modgraph-usa.com
Subject: Re: Overriding the optimizer
In-Reply-To: <43A25372.8090706@modgraph-usa.com>
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