<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:garamond,new york,times,serif;font-size:12pt">Hi Kevin,<br><br>I assumed I have no results because when I load one of the working queries as a view (eg. select st_buffer(the_geom,0.1)) in QGIS, or in ArcGIS, I see all my results as I would expect, but when I modify the query to st_union(st_buffer()), all my parcels disappear and I have a blank canvas.<br><br>Also, with st_isvalid(st_union(st_buffer(the_geom,0.1))) returning null (neither t nor f) I guess I just assumed. Anyways, results for your suggestions are inline, below. <br><br><div style="font-family: garamond,new york,times,serif; font-size: 12pt;">Thanks for your help. Any further ideas?<br><br>Lee.<br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b>
Kevin Neufeld <kneufeld@refractions.net><br><b><span style="font-weight: bold;">To:</span></b> postgis-users@postgis.refractions.net<br><b><span style="font-weight: bold;">Sent:</span></b> Tue, September 14, 2010 12:12:46 AM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [postgis-users] unioning a buffer - bug?<br></font><br>
How are you determining you have no results? <br>
<br>
Try:<br>
<tt>CREATE TABLE results AS<br>
SELECT st_union(st_buffer(the_geom,0.1)) as the_geom <br>
FROM base.current_assessment_parcel;<br>
<br><span style="font-weight: bold; color: rgb(127, 0, 63);">NOTICE: TopologyException: found non-noded intersection between 586714 4.95189e+006, 586714 4.95189e+006 and 586714 4.95189e+006, 586739 4.9519e+006 586714 4.95189e+006</span><br style="font-weight: bold; color: rgb(127, 0, 63);"><span style="font-weight: bold; color: rgb(127, 0, 63);">Query returned successfully with no result in 1078 ms.</span><br><br><br><br>
SELECT count(*) FROM results;<br><br><span style="font-weight: bold; color: rgb(127, 0, 63);">1</span><br><br>
SELECT ST_Summary(the_geom) FROM results;</tt><br>
<br><span style="color: rgb(127, 0, 63);">This returns blank.</span><br><br><span style="font-family: monospace;"><br>(snip)<br></span><tt>
</tt><br>
-- Kevin<br>
<br>
On 9/13/2010 7:07 AM, Lee wrote:
<blockquote type="cite">
<div style="font-family: garamond,new york,times,serif; font-size: 10pt; color: rgb(3, 61, 33);"><font size="3"><span style="font-weight: bold;">So after some googling I see
similar problems, but no solutions posted.</span><br style="font-weight: bold;">
<br style="font-weight: bold;">
<span style="font-weight: bold;">I am trying to union a buffer, but
the query is returning no results. Here is ultimately what I would
like to achieve:</span></font><br>
<br>
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0); font-weight: bold;">select
st_union(st_buffer(the_geom,0.1)) as the_geom from
base.current_assessment_parcel</span><br>
<br>
<font size="3"><span style="font-weight: bold;">Here are some
troubleshooting steps I have taken to try narrow it down:</span></font><br>
<br style="color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">select
st_isvalid(the_geom) a from base.current_assessment_parcel group by a</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">TRUE</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">select
st_isvalid(st_buffer(the_geom,0.1)) a from
base.current_assessment_parcel group by a</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">TRUE</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">select
st_isvalid(st_union(the_geom)) from base.current_assessment_parcel</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">TRUE</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">select
st_isvalid(st_union(st_buffer(the_geom,0.1))) from
base.current_assessment_parcel</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">NOTICE:
TopologyException: found non-noded intersection between 586714
4.95189e+006, 586714 4.95189e+006 and 586714 4.95189e+006, 586739
4.9519e+006 586714 4.95189e+006</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">Total
query runtime: 859 ms.</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Courier New,courier,monaco,monospace,sans-serif; color: rgb(0, 0, 0);">1
row retrieved.</span><br style="font-family: Courier New,courier,monaco,monospace,sans-serif;">
<font size="3"><span style="font-weight: bold;">(returns blank record)</span></font><br>
<br style="font-family: garamond,new york,times,serif;">
<div style="font-family: Courier New,courier,monaco,monospace,sans-serif;"><font size="3"><span style="font-family: garamond,new york,times,serif; font-weight: bold;"> And
just for fun</span></font><br>
<span style="color: rgb(0, 0, 0);">select
st_isvalid(st_buffer(st_union(the_geom),0.1)) a from
base.current_assessment_parcel</span><br style="color: rgb(0, 0, 0);">
<span style="color: rgb(0, 0, 0);">TRUE</span><br style="color: rgb(0, 0, 0);">
</div>
<font size="3"><br style="font-family: Courier New,courier,monaco,monospace,sans-serif; font-weight: bold;">
</font>
<div><font size="3"><span style="font-weight: bold;">I guess my next
step would be to try the snap to grid functions, but the first query
above should work, shouldn't it?</span><br style="font-weight: bold;">
<br style="font-weight: bold;">
<span style="font-weight: bold;">Any help appreciated. Thanks.</span><br style="font-weight: bold;">
<span style="font-weight: bold;">Lee</span></font><br>
</div>
</div>
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