[postgis-users] Benshmark postgis

[Arnaud Vandecasteele]

Hi Stefan,


Thank you for your help and for the links.
It will help me a lot in my future works.

Regards

Arnaud

On Wed, Dec 15, 2010 at 2:30 PM, Stefan Keller <sfkeller at gmail.com> wrote:
> Hi Arnaud,
>
> Sorry for coming late to this discussion.
>
> I can offer another random generator (see below) as well as a
> well-defined benchmark based on real world data: "The HSR Texas
> Spatial Database Benchmark" (see http://www.gis.hsr.ch/wiki/Benchmark
> ). If you want larger real world data then one could tage
> OpenStreetMap data. But this still needs some schema mapping before,
> like we do with our osm2gis converter (see OpenStreetMap-in-a-Box:
> http://dev.ifs.hsr.ch/osminabox ).
> Perhaps this helps doing your benchmarks.
>
> Yours, S.
>
> -----------------------------------------------------------------
> -- Generate random point geometries (2D) given a boundary polygon
> -- Source from WKTRasterTutorial01 (Credits to Paul Racine)
> -----------------------------------------------------------------
> DROP FUNCTION IF EXISTS ST_RandomPoints(geom geometry, nb int);
> --
> CREATE OR REPLACE FUNCTION ST_RandomPoints(geom geometry, nb int)
> RETURNS SETOF geometry
> LANGUAGE 'plpgsql' IMMUTABLE STRICT
> AS $$
> DECLARE
>  pt geometry;
>  xmin float8;
>  xmax float8;
>  ymin float8;
>  ymax float8;
>  count integer := 0;
> BEGIN
>  IF (ST_GeometryType(geom) != 'ST_Polygon' )
>    AND (ST_GeometryType(geom) != 'ST_MultiPolygon') THEN
>    RAISE EXCEPTION 'Attempting to get random point in a non polygon geometry';
>  END IF;
>  SELECT ST_XMin(geom), ST_XMax(geom), ST_YMin(geom), ST_YMax(geom)
>    INTO xmin, xmax, ymin, ymax;
>  WHILE count < nb LOOP
>    SELECT ST_SetSRID(
>        ST_MakePoint(xmin + (xmax - xmin) * random(),
>                     ymin + (ymax - ymin) * random()), ST_SRID(geom))
>      INTO pt;
>    IF ST_Contains(geom, pt) THEN
>      count := count + 1;
>      RETURN NEXT pt;
>    END IF;
>  END LOOP;
>  RETURN;
> END;
> $$
>
> -- Tests:
> SELECT generate_series(1, 5) AS id,
> ST_AsText(ST_RandomPoints(ST_MakeEnvelope(-180, -90, 180, 90, 4326),
> 5));
> SELECT id, ST_AsText(ST_RandomPoint(ST_MakeEnvelope(-180, -90, 180,
> 90, 4326))) FROM generate_series(1, 5) AS id;
> SELECT id, ST_AsText(ST_RandomPoint(ST_MakeEnvelope(45.82, 5.9, 47.84,
> 10.58, 4326))) FROM generate_series(1, 5) AS id;
> SELECT generate_series(1, 5) AS id,
> ST_AsText(ST_RandomPoints(ST_GeomFromText('POLYGON((480408
> 75436,484818 299965,835118 303541,844109 79149,480408 75436))',
> 21781),5));
>
>
>
> 2010/11/26 strk <strk at keybit.net>:
>> On Fri, Nov 26, 2010 at 09:38:09AM +0100, Arnaud Vandecasteele wrote:
>>> I understand better the interest of the Gis Index !  Thank you for your answer.
>>> I do not want to evaluate the postgis vs other database, just the time
>>> the queries will take for 1000 10 000 or more objects.
>>> The use case will be this one :
>>> We have several thousands of vessels and every 5 seconds I must do a
>>> query to check if they are or not in a dangerous area?
>>
>> How do dangerous areas look ?
>> Do their bounding boxes overlap much or not at all ?
>> Ho many areas ?
>> Do areas move often or could you "prepare" them to take
>> the most out of the index ?
>>
>> --strk;
>>
>>  ()   Free GIS & Flash consultant/developer
>>  /\   http://strk.keybit.net/services.html
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>>
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-- 
--------------------------------------------------------------------
Van De Casteele Arnaud
Mines Paris Tech - CRC
Sophia-Antipolis
0698 24 25 29
SIG - WebMapping - SOLAP - BI - GeoCollaboration

Web Site
http://geotribu.net/
http://www.sismaris.org/