| From: | Nikolas Everett <nik9000(at)gmail(dot)com> |
|---|---|
| To: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
| Cc: | sthomas(at)optionshouse(dot)com, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Thinking About Correlated Columns (again) |
| Date: | 2013-05-15 17:30:57 |
| Message-ID: | CAPmjWd08=Pk2+fSGeg61iAKY03YUySC1Ce5tpA-hGBZn59=3Aw@mail.gmail.com |
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| Lists: | pgsql-performance |
On Wed, May 15, 2013 at 11:52 AM, Heikki Linnakangas <
hlinnakangas(at)vmware(dot)com> wrote:
> On 15.05.2013 18:31, Shaun Thomas wrote:
>
>> I've seen conversations on this since at least 2005. There were even
>> proposed patches every once in a while, but never any consensus. Anyone
>> care to comment?
>>
>
> Well, as you said, there has never been any consensus.
>
> There are basically two pieces to the puzzle:
>
> 1. What metric do you use to represent correlation between columns?
>
> 2. How do use collect that statistic?
The option that always made the most sense to me was having folks ask
postgres to collect the statistic by running some command that marks two
columns as correlated. This could at least be a starting point.
Nik
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