[postgis-users] Mixing LINESTRING and MULTILINESTRING data

[Ben Madin]

G'day Simon,

Thanks for you help,

On 08/01/2009, at 5:01 AM, postgis-users- 
request at postgis.refractions.net wrote:

> Grab the definition of this CHECK constraint by clicking on the  
> table in pgAdminIII. Then do this:
>
> ALTER TABLE gis_roads DROP CONSTRAINT enforce_geotype_the_geom;
> ALTER TABLE gis_roads ADD CONTRAINT enforce_geotype_geom CHECK  
> (geometrytype(the_geom) IN  
> ('LINESTRING'::text,'MULTILINESTRING'::text) OR gethe_geomom IS NULL);
>
> It will now allow linestrings and multilinestrings to be inserted  
> into the table.


Great - I had some sense the the storage of a geometry type was  
slightly more primitive than that.


>> 3. Is there any reason I wouldn't want to mix the two data types...
>> are linestrings more efficiently handled etc.
>
> I'm not an expert on the specifics of PostGIS but if the object is a  
> linestring then store and index it as a linestring and remove the  
> additional handling required to extract the linestring from the  
> multilinestring for processing and rendering. Has to be a little bit  
> faster.


OK - thanks again - it is only a small table by the standards of some  
(90000 rows)

cheers

Ben


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Ben Madin
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