Re: Statistics and selectivity estimation for ranges

From: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
To: Alexander Korotkov <aekorotkov(at)gmail(dot)com>
Cc: Jeff Davis <pgsql(at)j-davis(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Statistics and selectivity estimation for ranges
Date: 2013-03-14 13:44:19
Message-ID: 5141D433.6020709@vmware.com
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On 01.03.2013 16:22, Alexander Korotkov wrote:
> On Wed, Mar 13, 2013 at 11:10 PM, Heikki Linnakangas<
> hlinnakangas(at)vmware(dot)com> wrote:
>
>> On 01.03.2013 16:22, Alexander Korotkov wrote:
>>
>>>> frac = area / (length2 - length1);
>>>>
>>> you can get NaN result. I've especially adjusted the code to get more of
>>> less correct result in this case.
>>
>> Hmm, good point. I think I managed to fix those cases in the attached
>> version. Is there any other corner case that I missed?
>
> Did you try test case by Jeff Davis on this thread?
> http://www.postgresql.org/message-id/1355167304.3896.37.camel@jdavis
> I try it with attached version of patch and get NaN estimate.

Thanks, fixed that too.

Committed with a little bit more clean up and fixes. Thank you for
bearing with this long process :-). And many thanks Jeff for the review,
and sorry that I forgot to credit you for that in the commit message.

- Heikki

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