[postgis-users] Postgis functions returning hidden weird characters! (?)

[Paul Ramsey]

Does

select ST_AsSVG('GEOMETRYCOLLECTION EMPTY'::geometry,0,5);

give the same odd result? (Should, it's the same fundamental input...)
I'm not sure what you're seeing though, as all attempts in the
database to find anything odd in the input fail for me:

geog=# select length(ST_AsSVG('GEOMETRYCOLLECTION EMPTY'::geometry,0,5));
length
--------
      0
(1 row)

geog=# select '|' || ST_AsSVG('GEOMETRYCOLLECTION EMPTY'::geometry,0,5) || '|';
?column?
 ----------
 ||
(1 row)

Could be a windows platform only thing... ?

P

On Sat, Mar 6, 2010 at 12:02 PM, Vyron Antoniou <v.antoniou at ucl.ac.uk> wrote:
> Hi,
>
> This is a weird one!
>
> If you run the following sql:
>
> select ST_AsSVG(ST_Difference(
> ST_LineFromText('LINESTRING(528085.304556059
> 182402.75252444,528057.189235888 182383.627714979,528078.925527415
> 182348.523254458,528110.016845328 182367.72322892,528119.206862483
> 182351.764509452,528065.429111811 182316.692226383,528019.682277422
> 182382.682354742,528076.562322635 182418.577931056,528085.304556059
> 182402.75252444)'),
> ST_Difference(ST_LineFromText('LINESTRING(528085.304556059
> 182402.75252444,528057.189235888 182383.627714979,528078.925527415
> 182348.523254458,528110.016845328 182367.72322892,528119.206862483
> 182351.764509452,528065.429111811 182316.692226383,528019.682277422
> 182382.682354742,528076.562322635 182418.577931056,528085.304556059
> 182402.75252444)'), ST_LineFromText('LINESTRING(528609 182468,528009
> 182468)'))
> ),0,5)
>
> It sees like that you are getting nothing as a response (which is
> geometrically correct!)
>
> If you run this sql:
> select ST_AsSVG(ST_Difference(
> ST_LineFromText('LINESTRING(528930.958778316 181668,528945.758383221
> 181621.10086763,528907.323783 181609.420947433,528915.910261821
> 181576.356315477,528917.004045659 181556.777339062,528910.734095004
> 181545.323813335,528902.462041152 181542.732665401,528889.242540907
> 181547.159913121,528878.071632731 181564.70288216,528866.478880465
> 181598.881969597,528848.921015863 181656.67822709,528885.788489116
> 181668,528930.958778316 181668)'),
> ST_Difference(ST_LineFromText('LINESTRING(528930.958778316
> 181668,528945.758383221 181621.10086763,528907.323783
> 181609.420947433,528915.910261821 181576.356315477,528917.004045659
> 181556.777339062,528910.734095004 181545.323813335,528902.462041152
> 181542.732665401,528889.242540907 181547.159913121,528878.071632731
> 181564.70288216,528866.478880465 181598.881969597,528848.921015863
> 181656.67822709,528885.788489116 181668,528930.958778316 181668)'),
> ST_LineFromText('LINESTRING(529209 181668,528609 181668)'))
> ),0,5)
>
> You get: "M 528885.78849 -181668 L 528930.95878 -181668" which is also
> geometrically correct.
>
> The problem is that if you try to parse the responses at the server (say
> with PHP) in order to determine if you have any data returned or not, you
> would be surprised to realize that the first response is not a completely
> empty response (!) but instead there is something hidden there which looks
> like: hˆ§□□, while with the second one you get exactly what
> you see.
>
> Someone could argue that this problem is caused by other factors not
> related to postgis but the thing is that this combination of postgis
> queries and PHP parsing didn’t used to cause any problems in previous
> versions.
>
> I’m running PostgreSQL 8.4 with Postgis 1.5 for 8.4 on Windows XP
>
> Any suggestions?
>
> Thanks
> Byron
>
>
>
>
>
>
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