Message-ID: <43A25372.8090706@modgraph-usa.com>
Date: Thu, 15 Dec 2005 21:41:06 -0800
From: "Craig A. James" <cjames@modgraph-usa.com>
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CC: pgsql-performance@postgresql.org
Subject: Re: Overriding the optimizer
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	<43A1C40D.8040006@paradise.net.nz>
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	<43A22BE3.6020103@modgraph-usa.com> <20051216052025.GB691@filer>
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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