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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Okay I did some more snooping of the distance outputs.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Using this query that consistently fails:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>create table test (geo geometry);<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> insert into test values <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> ('0101000020E61000007D91D0967329E4BF6631B1F9B8D64A40'::geometry), <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> ('0101000020E6100000E2AFC91AF510C1BFCDCCCCCCCCAC4A40'::geometry);<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>set enable_seqscan = false;<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>select *, '0101000020E610000092054CE0D6DDE5BFCDCCCCCCCCAC4A40'::geometry <-> geo , ST_Distance('0101000020E610000092054CE0D6DDE5BFCDCCCCCCCCAC4A40'::geometry, geo) <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>from test ORDER BY geo <-><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>('0101000020E610000092054CE0D6DDE5BFCDCCCCCCCCAC4A40'::geometry);<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> ?column? | st_distance<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>-------------------+-------------------<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> 0.331823813642119 | 0.331823813642119<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'> 0.55 | 0.55<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>(2 rows)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>The issue seems to be with the second record that the approximate distance 0.5500000111921 is just a wee bit bigger than the actual distances.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Which as you said should never happen.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>NOTICE: bbox2df_distance: (0.331818528656)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>NOTICE: bbox2df_distance: (0.550000011921)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>NOTICE: index returned tuples in wrong order. cmp: -1<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Does this create beaming lights in your head?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:.5in'><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'> postgis-devel [mailto:postgis-devel-bounces@lists.osgeo.org] <b>On Behalf Of </b>Paul Ramsey<br><b>Sent:</b> Tuesday, January 03, 2017 10:00 AM<br><b>To:</b> PostGIS Development Discussion <postgis-devel@lists.osgeo.org><br><b>Subject:</b> Re: [postgis-devel] Recheck on Points broken<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p><div><p class=MsoNormal style='margin-left:.5in'>Are we 100% sure this is a float/double issue? The distance between two float boxes should always be *smaller* than the actual distance between two objects, since the float box extrema are always moved *away* from the original object when the float boxes are created. So from a "theoretical mechanics" perspective this shouldn't actually be the source of the problem.<o:p></o:p></p><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>From a real world point-of-view, how could it still be the problem?<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>- maybe the box generation code has a short circuit for points which doesn't do the correct thing? Pretty sure it doesn't, but.<o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:.5in'>- something else?<br><br>P<o:p></o:p></p></div></div><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p><div><p class=MsoNormal style='margin-left:.5in'>On Tue, Jan 3, 2017 at 4:54 AM, Regina Obe <<a href="mailto:lr@pcorp.us" target="_blank">lr@pcorp.us</a>> wrote:<o:p></o:p></p><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><p class=MsoNormal style='margin-left:.5in'><br>>> Anyrate if there is nothing that can be done about ensuring index<br>>> distance is always less or equal to actual distance<br><br>> I remember we were all happy about having *real* distance with a more recent PostgreSQL. If that's not the case (as the user reports) we should try to find a way to provide both mechanisms.<br>> Two different operators, maybe ?<br>> --strk;<br><br>We've already got two different operators. We have <#> which doesn't use recheck and that's what I told the user to use, until we resolve this.<br><br>The thing is the <-> I think pretty much for all reasonable purposes returns the right order for points (and in fact in this case yields the same value and <-> I think in all cases it will).<br><br>So it's just the float4/float8 mess why it screws up and it Errors noisily in PostgreSQL land where we cannot control.<br><br>I hate telling people to if you have point / point use <#> and if you have others you can safely use <->. That's sooo unfriendly.<br><br>I think the best thing is just to not have point-point checks use recheck. Can we do that easily? That's what PostgreSQL point/point does.<br>That way we don't fall into the PostgreSQL box trap of<br><br>"Hey -- how come your index distance is bigger than your computed distance. What kind of monster are you? Screw you!"<br><br>Thanks,<br>Regina<o:p></o:p></p><div><div><p class=MsoNormal style='margin-left:.5in'><br>_______________________________________________<br>postgis-devel mailing list<br><a href="mailto:postgis-devel@lists.osgeo.org">postgis-devel@lists.osgeo.org</a><br><a href="http://lists.osgeo.org/mailman/listinfo/postgis-devel" target="_blank">http://lists.osgeo.org/mailman/listinfo/postgis-devel</a><o:p></o:p></p></div></div></blockquote></div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div></div></body></html>