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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>How many records do you have in a / b<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>What does this query return and point counts also impact performance<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>SELECT COUNT(*), MAX(ST_NPoints(geom))<o:p></o:p></p><p class=MsoNormal>FROM my_fishbones<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Also I’d think you’d want to leave out compare with a.id = b.id<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I also think the && is redundant as crosses already has a built in index check<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>SELECT a.*, <a href="http://b.id">b.id</a><br>FROM my_fishbones a INNER JOIN my_fishbones b ON (a.id <> b.id AND ST_Crosses(a.geom,b.geom) )<br><br><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><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 7:53 AM<br><b>To:</b> PostGIS Users Discussion <postgis-users@lists.osgeo.org><br><b>Subject:</b> 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 There!<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>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><o:p> </o:p></p></div><div><p class=MsoNormal>SELECT a.*, <a href="http://b.id">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><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks in advance!<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Bo Guo<o:p></o:p></p></div></div></div></div></body></html>