Re: Correlation in cost_index()

On Fri, 8 Aug 2003 16:53:48 -0700, Sean Chittenden
<sean(at)chittenden(dot)org> wrote:
># SHOW effective_cache_size ;
> effective_cache_size
>----------------------
> 4456
>(1 row)

Only 35 MB? Are you testing on such a small machine?

>The stats are attached && bzip2 compressed.

Nothing was attached. Did you upload it to your web site?

>> >I can say with pretty high confidence that the patch to use a
>> >geometric mean isn't correct

>... the problem with your patch was
>that it picked an index less often than the current code when there
>was low correlation.

In cost_index.sxc I get lower estimates for *all* proposed new
interpolation methods. Either my C code doesn't implement the same
calculations as the spreadsheet, or ...

>I manually applied bits of it [...]

... could this explain the unexpected behaviour?

I'm currently downloading your dump. Can you post the query you
mentioned above?

Servus
Manfred