Re: Overriding the optimizer

From: Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>
To: "Craig A(dot) James" <cjames(at)modgraph-usa(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Overriding the optimizer
Date: 2005-12-16 02:25:22
Message-ID: 43A22592.1000101@familyhealth.com.au
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> > Right on. Some of these "coerced" plans may perform > much better.
> If so, we can look at tweaking your runtime
> > config: e.g.
> >
> > effective_cache_size
> > random_page_cost
> > default_statistics_target
> >
> > to see if said plans can be chosen "naturally".
>
> I see this over and over. Tweak the parameters to "force" a certain
> plan, because there's no formal way for a developer to say, "I know the
> best plan."

No, this is "fixing your wrongn, inaccurate parameters so that
postgresql can choose a better plan".

I don't necessarily disagree with your assertion that we need planner
hints, but unless you or someone else is willing to submit a patch with
the feature it's unlikely to ever be implemented...

Chris

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