Re: Query optimizer 8.0.1 (and 8.0)

Bruce Momjian wrote:
> Jim C. Nasby wrote:
> 
>>On Mon, Feb 14, 2005 at 09:55:38AM -0800, Ron Mayer wrote:
>> 
>>
>>>I still suspect that the correct way to do it would not be
>>>to use the single "correlation", but 2 stats - one for estimating
>>>how sequential/random accesses would be; and one for estimating
>>>the number of pages that would be hit.  I think the existing
>>>correlation does well for the first estimate; but for many data
>>>sets, poorly for the second type.
>>
>> 
>>Should this be made a TODO? Is there some way we can estimate how much
>>this would help without actually building it?
> 
> 
> I guess I am confused how we would actually do that or if it is
> possible.
> 
I spent a while on the web looking for some known way to calculate
"local" correlation or "clumping" in some manner analogous to how we do
correlation currently. As yet I have only seen really specialized
examples that were tangentially relevant. We need a pet statistician to ask.

regards

Mark