Re: -HEAD planner issue wrt hash_joins on dbt3 ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Matteo Beccati <php(at)beccati(dot)com>
Cc: Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: -HEAD planner issue wrt hash_joins on dbt3 ?
Date: 2006-09-18 13:51:19
Message-ID: 27013.1158587479@sss.pgh.pa.us
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Matteo Beccati <php(at)beccati(dot)com> writes:
> I cannot see anything bad by using something like that:
> if (histogram is large/representative enough)

Well, the question is exactly what is "large enough"? I feel a bit
uncomfortable about applying the idea to a histogram with only 10
entries (especially if we ignore two of 'em). With 100 or more,
it sounds all right. What's the breakpoint?

regards, tom lane

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