| From: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Statistics and selectivity estimation for ranges |
| Date: | 2012-08-12 21:11:51 |
| Message-ID: | CAPpHfdtMUSF64MaRNn+fxMZxmN_BmGftTfUYn3=3MoDo1saDLQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Aug 9, 2012 at 12:44 AM, Alexander Korotkov <aekorotkov(at)gmail(dot)com>wrote:
> My conclusion is so, that current errors are probably ok for selectivity
> estimation. But taking into attention that generated datasets ideally fits
> assumptions of estimation, there could be room for improvement. Especially,
> it's unclear why estimate for "<@" and "@>" have much greater error than
> estimate for "&&". Possibly, it's caused by some bugs.
>
ITSM, I found reason of inaccuracy. Implementation of linear interpolation
was wrong. Fixed version is attached. Now, need to rerun tests, possible
refactoring and comments rework.
------
With best regards,
Alexander Korotkov.
| Attachment | Content-Type | Size |
|---|---|---|
| range_stat-0.4.patch.gz | application/x-gzip | 10.4 KB |
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