[postgis-devel] RectDistance

[Paul Ramsey]

Oh, I neglected to mention: some performance queries and results
catalogued here, using my favourite BC political boundaries data (poly
vs poly).

https://gist.github.com/pramsey/9638940582bd45d74c7d0fb1d47f6083

I suppose some tests with points/lines in particular would help to
confirm cut-off points for complexity.

P


On Thu, Feb 22, 2018 at 11:46 AM, Paul Ramsey <pramsey at cleverelephant.ca> wrote:
> I have now added a _ST_DistanceRectTreeCached(geom, geom) that does
> caching, so for cases with nested loop joins we should see improved
> performance. There's still cases (small geom vs small geom) that are
> handled better with the existing code. And I recall that Nik found
> some large cases that are degenerate too?
> Anyways, it seems like the final implementation of Distance() will end
> up being a hodgepodge with some magic number rules in the middle
> determining which code line to use.
> P
>
>
> On Tue, Feb 20, 2018 at 1:53 PM, Paul Ramsey <pramsey at cleverelephant.ca> wrote:
>> OK, it's in there, for those who want to try it out,
>> _ST_DistanceRectTree(g1 geometry, g2 geometry)
>> There is no caching in this version, so it's building and tossing away
>> the trees at every invocation.
>> P.
>>
>> On Tue, Feb 20, 2018 at 1:49 PM, Bborie Park <dustymugs at gmail.com> wrote:
>>> +1
>>>
>>> On Tue, Feb 20, 2018 at 12:14 PM, Regina Obe <lr at pcorp.us> wrote:
>>>>
>>>> No objections from me.  +1 to just bring it in 2.5.
>>>>
>>>> I'm too lazy to test another branch, but if in place, I'd be willing to
>>>> test it out.
>>>>
>>>> Thanks,
>>>> Regina
>>>>
>>>> -----Original Message-----
>>>> From: postgis-devel [mailto:postgis-devel-bounces at lists.osgeo.org] On
>>>> Behalf Of Paul Ramsey
>>>> Sent: Tuesday, February 20, 2018 2:26 PM
>>>> To: PostGIS Development Discussion <postgis-devel at lists.osgeo.org>
>>>> Subject: [postgis-devel] RectDistance
>>>>
>>>> Hey all,
>>>>   I've had a branch running for a while, that Nik has tested a little, for
>>>> tree-based distance calculations. I've been doing some testing on it and
>>>> finding that when it's good, it's very very good (10x improvements when
>>>> dealing with large geometries) and when it's bad, it's not so great (3x
>>>> worse than existing naive distance on small-vs-small geometries).
>>>>   All this so far without also reaching into the next obvious enhancement,
>>>> adding a caching behaviour, like the point-in-polygon/geos code. That will
>>>> make everything about 2x faster yet, as about 50% of the time seems to be
>>>> spent in building up trees.
>>>>   I'd like to merge my branch in, along with a temporary testing function
>>>> _ST_DistanceRectTree(geom, geom) so that we can figure out how we exactly
>>>> want to put this code to use. Any objections? If nothing else, it will
>>>> replace the current dead code lying in lwtree.c.
>>>>
>>>> P.
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