[postgis-devel] ST_DistanceCached(geog, geog), ST_DWithinCached(geog, geog)

[Paul Ramsey]

Shoowah.

https://dl.dropbox.com/u/1184727/geogcached.zip


On Tue, Jun 19, 2012 at 3:06 PM, Mark Cave-Ayland
<mark.cave-ayland at ilande.co.uk> wrote:
> On 19/06/12 04:46, Paul Ramsey wrote:
>
>> I've temporarily committed two functions to Geography support in trunk,
>>
>> ST_DistanceCached(geog, geog)
>> ST_DWithinCached(geog, geog, double)
>>
>> These would take over from ST_Distance(geog, geog) and
>> ST_DWithin(geog, geog, double) when good behavior, performance are
>> confirmed. The only difference between them and their antecedants is
>> that they try and cache an internal geography tree. This seems to make
>> a massive, monster difference for distance calculations. Oddly, I
>> haven't been able to demonstrate a speed difference in DWithin yet, at
>> least not with fairly small tolerance values.
>>
>> Please feel free to test and let me know how things go.
>
>
> Oh interesting. Do you have any easy-to-demonstrate test cases to run in an
> .sql file so we can get a feel for the speedup?
>
>
> ATB,
>
> Mark.
>
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