Re: Double sorting split patch

On 22.09.2011 22:12, Alexander Korotkov wrote:
> Patch without that dead code is attached.

Thanks.

Can you elaborate the consider-split algorithm? The criteria to select 
the new split over the previously selected one is this:
> !         /*
> !          * If ratio is acceptable, we should compare current split with
> !          * previously selected one. If no split was selected then we select
> !          * current anyway. Between splits of one dimension we search for
> !          * minimal overlap (allowing negative values) and minimal ration
> !          * (between same overlaps. We switch dimension if find less overlap
> !          * (non-negative) or less range with same overlap.
> !          */
> !         range = diminfo->upper - diminfo->lower;
> !         overlap = ((leftUpper) - (rightLower)) / range;
> !         if (context->first ||
> !             (context->dim == dimNum &&
> !              (overlap < context->overlap ||
> !               (overlap == context->overlap && ratio > context->ratio))) ||
> !             (context->dim != dimNum &&
> !              ((range > context->range &&
> !                non_negative(overlap) <= non_negative(context->overlap)) ||
> !               non_negative(overlap) < non_negative(context->overlap)))
> !             )
> !         {

Why are negative overlaps handled differently across dimensions and 
within the same dimension? Your considerSplit algorithm in the SYRCoSE 
2011 paper doesn't seem to make that distinction.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com