<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta name="Microsoft Theme 2.00" content="Etienne Desgagné
Évimbec 011"><meta http-equiv=Content-Type content="text/html; charset=iso-8859-1"><meta name=Generator content="Microsoft Word 12 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Verdana;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";
color:black;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
pre
{mso-style-priority:99;
mso-style-link:"Préformaté HTML Car";
margin:0cm;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";
color:black;}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Texte de bulles Car";
margin:0cm;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Arial","sans-serif";
color:black;}
span.TextedebullesCar
{mso-style-name:"Texte de bulles Car";
mso-style-priority:99;
mso-style-link:"Texte de bulles";
font-family:"Arial","sans-serif";}
span.EmailStyle19
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:windowtext;}
span.apple-converted-space
{mso-style-name:apple-converted-space;}
span.PrformatHTMLCar
{mso-style-name:"Préformaté HTML Car";
mso-style-priority:99;
mso-style-link:"Préformaté HTML";
font-family:"Consolas","serif";
color:black;}
span.EmailStyle23
{mso-style-type:personal-reply;
color:black;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 90.0pt 72.0pt 90.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=FR-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span lang=EN-US>It take millisecond to me to when using </span><span lang=EN-US>ST_Intersects on a spatial join. What take much longer is when using ST_Intersection in the SELECT clause to effectively “clip” a layer with the other one…<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>My computer run under Windows 7 64bits with dual core 2.70GHZ and 8 Go RAM.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Is there anything I can do to check if it’s normal behavior on this platform or if something may be wrong on my installation?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Thanks<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Etienne</span><span lang=EN-US><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=FR style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>De :</span></b><span lang=FR style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> postgis-users-bounces@lists.osgeo.org [mailto:postgis-users-bounces@lists.osgeo.org] <b>De la part de</b> Jeff Lake<br><b>Envoyé :</b> 29 novembre 2012 09:15<br><b>À :</b> postgis-users@lists.osgeo.org<br><b>Objet :</b> Re: [postgis-users] Why PostGIS ST_Intersection much slower than ArcGIS Intersect ?<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal style='margin-bottom:12.0pt'>Must have something to do with windows and or memory ..<br>I use ST_Intersects daily on a Linux Server (PostGIS 2.0, PG 9.1.6) with a quad core Xeon and 16gb memory<br>it takes milliseconds on much larger layers ..<o:p></o:p></p><div><p class=MsoNormal><b>Jeff Lake</b><br><a href="http://www.michiganwxsystem.com">MichiganWxSystem</a><br><a href="http://www.allisonhouse.com">AllisonHouse</a><br><a href="http://www.grlevelxstuff.com">GRLevelXStuff</a><o:p></o:p></p></div><p class=MsoNormal>On 11/28/2012 16:22, Étienne Desgagné wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal><span lang=EN-US style='font-size:7.5pt;font-family:"Verdana","sans-serif";background:white'>Hello,<span class=apple-converted-space> </span></span><span lang=EN-US style='font-size:7.5pt;font-family:"Verdana","sans-serif"'><br><br><span style='background:white'> I don't want to denigrate PostGIS in any way and I know that my comparison may be wrong but I'm trying to understand why a basic ST_Intersection of two relatively small layers (< 1000 polygons) take about 1m40 sec in PostGIS(2.0 on PG 9.2 on Windows) while applying the ArcGIS Intersect on same layers and machine take about 2 sec?<span class=apple-converted-space> </span></span><br><br><span style='background:white'>I'm aware of some PostgreSQL tuning settings but even applying basic tuning recommendation for PostGIS I'm facing the same problem...<span class=apple-converted-space> </span></span><br><br><br></span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='font-size:7.5pt;font-family:"Verdana","sans-serif"'>My two layers also have a spatial index.</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US style='font-size:7.5pt;font-family:"Verdana","sans-serif"'><br><span style='background:white'>Is it normal behavior? Any suggestion for reaching better performance?<span class=apple-converted-space> </span></span><br><br><span style='background:white'>Note that I'm also using ST_Intersects on the join to filter only intersecting features...<span class=apple-converted-space> </span></span><br><br></span><span style='font-size:7.5pt;font-family:"Verdana","sans-serif";background:white'>Thanks a lot<span class=apple-converted-space> </span></span><span style='font-size:7.5pt;font-family:"Verdana","sans-serif"'><br><br><span style='background:white'>Etienne</span></span><o:p></o:p></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><br><br><br><o:p></o:p></span></p><pre>_______________________________________________<o:p></o:p></pre><pre>postgis-users mailing list<o:p></o:p></pre><pre><a href="mailto:postgis-users@lists.osgeo.org">postgis-users@lists.osgeo.org</a><o:p></o:p></pre><pre><a href="http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users">http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users</a><o:p></o:p></pre></blockquote><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p> </o:p></span></p></div></body></html>