Re: hist boundary duplicates bug in head and 8.3

From: "Nathan Boley" <npboley(at)gmail(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: hist boundary duplicates bug in head and 8.3
Date: 2009-01-06 23:36:32
Message-ID: 6fa3b6e20901061536t50b5674r58232a559aa3e146@mail.gmail.com
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>> For heavy tailed distributions, it is possible for analyze to
>> duplicate histogram boundaries.
>
> I don't think this is a bug.

hmmm... Well, I assumed it was a bug from a comment in analyze.

From ( near ) line 2130 in analyze.c

* least 2 instances in the sample. Also, we won't suppress values
* that have a frequency of at least 1/K where K is the intended
* number of histogram bins; such values might otherwise cause us to
* emit duplicate histogram bin boundaries.
*/

If this is expected, I'm also not sure what the use of maxmincount in
analyze is...

Thanks for the response,

Nathan

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