Re: hist boundary duplicates bug in head and 8.3 - Mailing list pgsql-hackers

From Nathan Boley
Subject Re: hist boundary duplicates bug in head and 8.3
Date
Msg-id 6fa3b6e20901061536t50b5674r58232a559aa3e146@mail.gmail.com
Whole thread Raw
In response to Re: hist boundary duplicates bug in head and 8.3  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: hist boundary duplicates bug in head and 8.3  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
>> 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
theintended* 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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