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<p class=MsoNormal><span style='color:#1F497D'>Credit where credit is due—the cleanGeometry
function listed below is written by </span>Horst Duester<span style='color:
#1F497D'>.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Best,<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Steve<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
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</v:shape><![endif]--><![if !vml]><img width=90 height=122
src="cid:image002.png@01CD1BCD.746AE2E0" align=left hspace=12
alt="http://www.clemetparks.com/images/esig/cmp-ms-90x122.png" v:shapes="_x0000_s1027"><![endif]><span
style='font-size:14.0pt;font-family:"Arial","sans-serif";color:#006C56'>Stephen
Mather<br>
</span><span style='font-family:"Arial","sans-serif";color:#006C56'>Geographic
Information Systems (GIS) Manager<br>
</span><span style='font-size:9.0pt;font-family:"Arial","sans-serif";
color:#006C56'>(216) 635-3243<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:9.0pt;font-family:"Arial","sans-serif";
color:#006C56'>svm@clevelandmetroparks.com<br>
</span><span style='color:#1F497D'><a href="http://www.clemetparks.com/"><span
style='font-size:9.0pt;font-family:"Arial","sans-serif";color:blue'>clevelandmetroparks.com</span></a><o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
</div>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net] <b>On Behalf Of </b>Stephen
V. Mather<br>
<b>Sent:</b> Monday, April 16, 2012 12:33 PM<br>
<b>To:</b> postgis-users@postgis.refractions.net<br>
<b>Subject:</b> [postgis-users] ST_MakeValid<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Hi All,<o:p></o:p></p>
<p class=MsoNormal>
Has anyone done any performance tests on ST_MakeValid? I had been using
Tim Sutton’s cleanGeometry function from circa 2010 (<a
href="http://linfiniti.com/2010/07/cleaning-geometries-inside-postgis/">http://linfiniti.com/2010/07/cleaning-geometries-inside-postgis/</a>)
to clean up geometries. Works most of the time—every now and then I throw
it something too big and harry and it runs for weeks and weeks and never (AFAI
have the patience for) completes. I’ve been looking forward to
ST_MakeValid.<o:p></o:p></p>
<p class=MsoNormal>
Today, a new Postgis 2.0 instance in hand, I was playing with a dataset with
9106 invalid geometries—all self intersecting geometries from
raster-->vector conversion in an un-named proprietary package. On a
whim, I decided to compare the speed of ST_MakeValid to Tim’s code, so first I
needed the correct functions:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><b><span style='font-family:"Courier New"'>psql -U postgres
-d test -f "C:\Program
Files\PostgreSQL\9.1\share\contrib\postgis-2.0\legacy.sql"<o:p></o:p></span></b></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Then a quick run through cleanGeometry:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><b><span style='font-family:"Courier New"'>CREATE TABLE
tpi_clean AS<o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-family:"Courier New"'>
SELECT gid, id, gridcode, "class name", cleanGeometry(geom)<o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-family:"Courier New"'>
FROM tpi;<o:p></o:p></span></b></p>
<p class=MsoNormal><span style='font-family:"Courier New"'><o:p> </o:p></span></p>
<p class=MsoNormal>And I get back:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><b><span style='font-family:"Courier New"'>Query returned
successfully: 1004952 rows affected, 955444 ms execution time.<o:p></o:p></span></b></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>If I run as ST_MakeValid,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><b><span style='font-family:"Courier New"'>CREATE TABLE
tpi_valid AS<o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-family:"Courier New"'>
SELECT gid, id, gridcode, "class name", ST_MakeValid(geom)<o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-family:"Courier New"'>
FROM tpi;<o:p></o:p></span></b></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>At 2300000 milliseconds, it is still running… .<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>This is PostgreSQL 9.1, PostGIS 2.0 USE_GEOS=1 USE_PROJ=1
USE_STATS=1, on Windows XP 32-bit. I have not yet tested on my Ubuntu
box… .<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thanks,<br>
Best,<o:p></o:p></p>
<p class=MsoNormal>Steve<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><!--[if gte vml 1]><v:shape id="cmp-ms-90x122.png" o:spid="_x0000_s1026"
type="#_x0000_t75" alt="http://www.clemetparks.com/images/esig/cmp-ms-90x122.png"
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</v:shape><![endif]--><![if !vml]><img width=90 height=122
src="cid:image002.png@01CD1BCD.746AE2E0" align=left hspace=12
alt="http://www.clemetparks.com/images/esig/cmp-ms-90x122.png" v:shapes="cmp-ms-90x122.png"><![endif]><span
style='font-size:14.0pt;font-family:"Arial","sans-serif";color:#006C56'>Stephen
Mather<br>
</span><span style='font-family:"Arial","sans-serif";color:#006C56'>Geographic
Information Systems (GIS) Manager<br>
</span><span style='font-size:9.0pt;font-family:"Arial","sans-serif";
color:#006C56'>(216) 635-3243<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:9.0pt;font-family:"Arial","sans-serif";
color:#006C56'>svm@clevelandmetroparks.com<br>
</span><a href="http://www.clemetparks.com/"><span style='font-size:9.0pt;
font-family:"Arial","sans-serif"'>clevelandmetroparks.com</span></a><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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