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--></style></head><body lang=EN-US link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal>What does <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>SELECT postgis_full_version();<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Return. I suppose doing a cross join there does result in an order of <span style='font-size:11.0pt;font-family:"Aptos Narrow",sans-serif;color:black'>6,728,232,002 checks.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Aptos Narrow",sans-serif;color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Aptos Narrow",sans-serif;color:black'>You definitely have a spatial index on your geometry column right?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Aptos Narrow",sans-serif;color:black'><o:p> </o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>What timing do you get with below, just want to rule out some performance issue with ST_Crosses<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>SELECT a.*, b.gad_globalid<br>FROM _tmp_fishbone a INNER JOIN _tmp_fishbone b ON (a.gad_globalid < b.gad_globalid AND ST_Intersects(a.geom,b.geom) );<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> Bo Guo <bo.guo@gisticinc.com> <br><b>Sent:</b> Thursday, February 5, 2026 12:59 PM<br><b>To:</b> Regina Obe <lr@pcorp.us><br><b>Cc:</b> PostGIS Users Discussion <postgis-users@lists.osgeo.org><br><b>Subject:</b> Re: Slowness in testing any crossing straight lines in a layer<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>Hi Regina! <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Your query returned "116002, 2".<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I ran the three variations of the ST_Crosses query, and here are the performance results.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>SELECT a.*, b.gad_globalid<br>FROM _tmp_fishbone a INNER JOIN _tmp_fishbone b ON (a.gad_globalid <> b.gad_globalid AND ST_Crosses(a.geom,b.geom) )<br>-- 33 minutes<br><br>SELECT a.*, b.gad_globalid<br>FROM _tmp_fishbone a INNER JOIN _tmp_fishbone b ON (a.gad_globalid < b.gad_globalid AND ST_Crosses(a.geom,b.geom) )<br>-- 17 minutes<br><br>SELECT a.*, b.gad_globalid<br>FROM _tmp_fishbone a INNER JOIN _tmp_fishbone b ON (a.gad_globalid < b.gad_globalid AND a.geom && b.geom AND ST_Crosses(a.geom,b.geom) )<br>-- 17 minutes<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>It seems that 17 mins is the best I can get?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks!<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Thu, Feb 5, 2026 at 8:06<span style='font-family:"Arial",sans-serif'> </span>AM Regina Obe <<a href="mailto:lr@pcorp.us" target="_blank">lr@pcorp.us</a>> wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>How many records do you have in a / b<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>What does this query return and point counts also impact performance<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>SELECT COUNT(*), MAX(ST_NPoints(geom))<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>FROM my_fishbones<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Also I’d think you’d want to leave out compare with <a href="http://a.id" target="_blank">a.id</a> = <a href="http://b.id" target="_blank">b.id</a><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>I also think the && is redundant as crosses already has a built in index check<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;margin-bottom:12.0pt'>SELECT a.*, <a href="http://b.id" target="_blank">b.id</a><br>FROM my_fishbones a INNER JOIN my_fishbones b ON (<a href="http://a.id" target="_blank">a.id</a> <> <a href="http://b.id" target="_blank">b.id</a> AND ST_Crosses(a.geom,b.geom) )<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> Bo Guo <<a href="mailto:bo.guo@gisticinc.com" target="_blank">bo.guo@gisticinc.com</a>> <br><b>Sent:</b> Thursday, February 5, 2026 7:53 AM<br><b>To:</b> PostGIS Users Discussion <<a href="mailto:postgis-users@lists.osgeo.org" target="_blank">postgis-users@lists.osgeo.org</a>><br><b>Subject:</b> Slowness in testing any crossing straight lines in a layer</span><o:p></o:p></p></div></div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Hi There!<o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>I have 100K straight lines in a layer - my_fishbone - with GIST indexed. However, the following SQL query did not finish within 20 minutes! Could you advise on any improvement ideas?<o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>SELECT a.*, <a href="http://b.id" target="_blank">b.id</a><br>FROM my_fishbones a, my_fishbones b<br>WHERE a.geom && b.geom <br> AND ST_Crosses(a.geom, b.geom)<o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Thanks in advance!<o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Bo Guo<o:p></o:p></p></div></div></div></div></div></div></blockquote></div></div></div></body></html>