Re: Commit fest 2014-12, let's begin!

On Mon, Dec 15, 2014 at 7:47 PM, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com
> wrote:
>
> On 12/15/2014 05:22 PM, Alexander Korotkov wrote:
>
>> On Mon, Dec 15, 2014 at 6:20 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>
>>>
>>> Alexander Korotkov <aekorotkov(at)gmail(dot)com> writes:
>>>
>>>> On Mon, Dec 15, 2014 at 4:12 PM, Heikki Linnakangas <
>>>>
>>> hlinnakangas(at)vmware(dot)com
>>>
>>>> wrote:
>>>>> Right. I also looked at it briefly, but I wasn't sure if we really want
>>>>> it. AFAICT, no-one has actually asked for that operator, it was written
>>>>> only to be an example of an operator that would benefit from the
>>>>>
>>>> knn-gist
>>>
>>>> with recheck patch.
>>>>>
>>>>
>>> Lack of recheck is major limitation of KNN-GiST now. People are not
>>>>
>>> asking
>>>
>>>> for that because they don't know what is needed to implement exact KNN
>>>>
>>> for
>>>
>>>> PostGIS. Now they have to invent kluges like this:
>>>> [ query using ORDER BY ST_Distance ]
>>>>
>>>
>>> It's not apparent to me that the proposed operator is a replacement for
>>> ST_Distance. The underlying data in an example like this won't be either
>>> points or polygons, it'll be PostGIS datatypes.
>>>
>>> In short, I believe that PostGIS could use what you're talking about,
>>> but I agree with Heikki's objection that nobody has asked for this
>>> particular operator.
>>>
>>
>> "polygon <-> point" is for sure not ST_Distance replacement. I was giving
>> this argument about KNN-GiST with recheck itself. "polygon <-> point" is
>> needed just as in-core example of KNN-GiST with recheck.
>>
>
> Right. I don't think point <-> polygon is too useful by itself, but we
> need an example in core that could make use KNN-GiST recheck patch. We
> can't write a regression test for it otherwise, for starters.
>
> Actually, we probably could've used the circle <-> polygon for that just
> as well...

Did you mean searching for circles or polygons in the last sentence?

------
With best regards,
Alexander Korotkov.