[postgis-devel] Another Data Point

[Paul Ramsey]

The glove is dropped indeed... why speculate when I have the Shark...
time to see where our time goes...

P

On Wed, Jan 21, 2009 at 8:55 AM, Martin Davis <mbdavis at refractions.net> wrote:
> Go for it, Regina!  The glove is dropped...
>
> Although I suspect this test may simply be running into the slower memory
> performance due to any or all of Postgres, C, GEOS compared to good ol'
> Java...  Hard to beat that tuned JVM memory manager!
>
> Obe, Regina wrote:
>>
>> Ah I think JTS was able to do this in about 40-50 seconds.  And my
>> version was able to beat out Kevin's nested by a small margin.  I'll
>> retest on mine.
>>
>> So I think we still need work here.
>>
>> I'm curious what would happen if I combined the algorithm I wrote with
>> the new ST_Union how things would fair.  In theory it should fair the
>> same, but I'm not really using Martin's cascaded union algorithm to the
>> letter.
>>
>>
>> -----Original Message-----
>> From: postgis-devel-bounces at postgis.refractions.net
>> [mailto:postgis-devel-bounces at postgis.refractions.net] On Behalf Of Paul
>> Ramsey
>> Sent: Wednesday, January 21, 2009 12:50 AM
>> To: PostGIS Development Discussion
>> Cc: lee.keel at uai.com
>> Subject: [postgis-devel] Another Data Point
>>
>> Using the original sample set from Lee Keel,
>>
>> With the old style ST_Union, 3 hours, 27 minutes:
>>
>> uniontest=# select st_area(st_union(the_geom)) from sample_poly;
>>      st_area
>> --------------------
>>  0.0324039850011104
>> (1 row)
>>
>> Time: 12419261.819 ms
>>
>>
>> With the new cascaded ST_Union, 4 minutes, 30 seconds, or 46 times
>> faster.
>>
>> uniontest=# select st_area(st_union_fast(the_geom)) from sample_poly;
>>      st_area
>> --------------------
>>  0.0324039850054305
>> (1 row)
>>
>> Time: 271618.181 ms
>>
>>
>> That's one nasty data set.
>>
>> P.
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>
> --
> Martin Davis
> Senior Technical Architect
> Refractions Research, Inc.
> (250) 383-3022
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