[postgis-devel] Another Data Point

Martin Davis mbdavis at refractions.net
Wed Jan 21 16:18:23 PST 2009 

I'm dancing! 

Obe, Regina wrote:
>
> Okay you can dance.  I'll say its a tie so all can dance :)
>
> -----Original Message-----
> From: postgis-devel-bounces at postgis.refractions.net on behalf of Paul 
> Ramsey
> Sent: Wed 1/21/2009 3:17 PM
> To: PostGIS Development Discussion
> Subject: Re: [postgis-devel] Another Data Point
>
> 15 seconds on OpenJump. I'll take my victories where I can get them,
> this is close enough.
>
> P
>
> On Wed, Jan 21, 2009 at 11:53 AM, Obe, Regina 
> <robe.dnd at cityofboston.gov> wrote:
> > I don't have my OpenJump available at the moment.
> >
> > Kevin or Paul you happen to have that? If not then I guess I can test
> > tomorrow and
> > then Paul can do his little dance :)
> >
> > Though would make more sense for Paul to do it so we are testing on 
> the same
> > hardware.
> >
> >
> > -----Original Message-----
> > From: postgis-devel-bounces at postgis.refractions.net on behalf of 
> Paul Ramsey
> > Sent: Wed 1/21/2009 2:50 PM
> > To: PostGIS Development Discussion
> > Subject: Re: [postgis-devel] Another Data Point
> >
> > Now can I do my little dance?
> >
> > uniontest=# SELECT geometrytype(_unite_garray_fast(ARRAY(SELECT
> > the_geom FROM sample_poly)));
> >  geometrytype
> > --------------
> >  MULTIPOLYGON
> > (1 row)
> >
> > Time: 24122.901 ms
> > uniontest=#
> >
> >
> >
> > On Wed, Jan 21, 2009 at 11:43 AM, Obe, Regina 
> <robe.dnd at cityofboston.gov>
> > wrote:
> >> Paul,
> >> I wouldn't proclaim victory on that alone.
> >>
> >> Do another test.  20 seconds sounds a little too short.
> >> I'm not saying it isn't right and my memory may be wrong on the JTS 
> result
> >> too.
> >> Besides JTS would have to collect geometries as well I imagine so you
> >> can't
> >> simply throw that out and proclaim victory.
> >>
> >>
> >> Test out
> >>
> >> SELECT geometrytype(st_unite_garray(ARRAY(SELECT the_geom FROM
> >> sample_poly)))
> >>
> >> Though that wouldn't be quite a true test either. But somewhere between
> >> the
> >> two would be the answer.
> >>
> >>
> >> -----Original Message-----
> >> From: postgis-devel-bounces at postgis.refractions.net on behalf of Paul
> >> Ramsey
> >> Sent: Wed 1/21/2009 1:58 PM
> >> To: PostGIS Development Discussion
> >> Subject: Re: [postgis-devel] Another Data Point
> >>
> >> Well, just running this:
> >>
> >> uniontest=# select geometrytype(collect(the_geom)) from sample_poly;
> >>   geometrytype
> >> --------------------
> >>  GEOMETRYCOLLECTION
> >> (1 row)
> >>
> >> Time: 261624.195 ms
> >>
> >> takes 251 of the 271 seconds the union operation took... the
> >> implication is that the GEOS portion of the work is on the order of 10
> >> seconds.
> >>
> >> P.
> >>
> >> On Wed, Jan 21, 2009 at 10:10 AM, Martin Davis 
> <mbdavis at refractions.net>
> >> wrote:
> >>> Could be...   It would be interesting to see whether GEOS is 
> faster than
> >>> JTS.   Needs a test environment able to run both pieces of code on the
> >>> same
> >>> hardware.
> >>>
> >>> Paul Ramsey wrote:
> >>>>
> >>>> I got another run in, right near the end, and it showed that
> >>>> GEOSUnionCascaded took only about 50% of the time in that slice. 
> There
> >>>> was still more memcpy'ing first. I bet GEOSUnionCascaded on its own
> >>>> would be as fast as JTS (or faster?).
> >>>>
> >>>> P.
> >>>>
> >>>> On Wed, Jan 21, 2009 at 9:05 AM, Paul Ramsey 
> <pramsey at cleverelephant.ca>
> >>>> wrote:
> >>>>
> >>>>>
> >>>>> Interesting! The Shark only samples for about 20 seconds, so I only
> >>>>> got the first 10% or so of the run, and the biggest user in that 
> time
> >>>>> period memcpy'ing in LWGEOM_accum (postgis) and
> >>>>> advance_transition_function (pgsql). So we are spending a 
> non-trivial
> >>>>> amount of time just accumulating the input...
> >>>>>
> >>>>> P
> >>>>>
> >>>>> On Wed, Jan 21, 2009 at 9:00 AM, Paul Ramsey
> >>>>> <pramsey at cleverelephant.ca>
> >>>>> wrote:
> >>>>>
> >>>>>>
> >>>>>> 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.
> >>>>>>>> _______________________________________________
> >>>>>>>> postgis-devel mailing list
> >>>>>>>> postgis-devel at postgis.refractions.net
> >>>>>>>> http://postgis.refractions.net/mailman/listinfo/postgis-devel
> >>>>>>>> -----------------------------------------
> >>>>>>>> The substance of this message, including any attachments, may be
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> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>
> >>>>>>> --
> >>>>>>> Martin Davis
> >>>>>>> Senior Technical Architect
> >>>>>>> Refractions Research, Inc.
> >>>>>>> (250) 383-3022
> >>>>>>>
> >>>>>>> _______________________________________________
> >>>>>>> postgis-devel mailing list
> >>>>>>> postgis-devel at postgis.refractions.net
> >>>>>>> http://postgis.refractions.net/mailman/listinfo/postgis-devel
> >>>>>>>
> >>>>>>>
> >>>>
> >>>> _______________________________________________
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> >>>> http://postgis.refractions.net/mailman/listinfo/postgis-devel
> >>>>
> >>>>
> >>>
> >>> --
> >>> Martin Davis
> >>> Senior Technical Architect
> >>> Refractions Research, Inc.
> >>> (250) 383-3022
> >>>
> >>> _______________________________________________
> >>> postgis-devel mailing list
> >>> postgis-devel at postgis.refractions.net
> >>> http://postgis.refractions.net/mailman/listinfo/postgis-devel
> >>>
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-- 
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022

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