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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><div><p class=MsoNormal>On Thu, Nov 15, 2018 at 8:20 AM Regina Obe <<a href="mailto:lr@pcorp.us">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-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><p class=MsoNormal><br>> -----Original Message-----<br>> From: postgis-devel [mailto:<a href="mailto:postgis-devel-bounces@lists.osgeo.org" target="_blank">postgis-devel-bounces@lists.osgeo.org</a>] On Behalf<br>> Of Sandro Santilli<br>> Sent: Thursday, November 15, 2018 5:25 AM<br>> To: PostGIS Development Discussion <<a href="mailto:postgis-devel@lists.osgeo.org" target="_blank">postgis-devel@lists.osgeo.org</a>><br>> Subject: Re: [postgis-devel] Making SFCGAL mandatory<br>> <br>> On Thu, Nov 15, 2018 at 01:08:54PM +0300, Darafei "Kom?pa" Praliaskouski<br>> wrote:<br>> <br>> > ><br>> > > Probably. I don't remember exactly why we chose to use GUC.<br>> > > Functions in their own schema like sfcgal.ST_Intersects() could have<br>> > > been a solution as well (?)<br>> ><br>> > Can we change that for PostGIS 3.0, so that instead of<br>> > postgis.backend=sfcgal one will set search_path=postgis_sfcgal,public?<br>> <br>> +1<br>> <br>> --strk;<br>> _______________________________________________<br>> postgis-devel mailing list<br>> <a href="mailto:postgis-devel@lists.osgeo.org" target="_blank">postgis-devel@lists.osgeo.org</a><br>> <a href="https://lists.osgeo.org/mailman/listinfo/postgis-devel" target="_blank">https://lists.osgeo.org/mailman/listinfo/postgis-devel</a><br>[Regina Obe] <br>What? NO -1<br><br>That is a super breaking change. We'd have to remove the postgis schema qualfications in SFCGAL since we wouldn't know where postgis is installed. We've already got issues with postgis.topology and postgis_tiger_geocoder because of this.<br>Let's not compound the issue.<o:p></o:p></p></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Agreed. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Yes, this would have be an interesting approach back when we had the option, but sort of assumes using specific install schemas as a general policy, which not everyone does.<o:p></o:p></p></div><div><p class=MsoNormal>Since I was complaining about it being a basically unused features, I was this morning wondering about removing the run-time backend switch? If we want to keep binding to specific CGAL functions that overlap GEOS functionality, then just naming them appropriately (CGAL_Intersects()? ST_IntersectsCGAL()?) would hardly be the end of the world.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>P.<o:p></o:p></p></div><div><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><b><i><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></i></b></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> So, this way another question arises: who is using SFCGAL backend overloads<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> and what are the use cases? What if we just drop SFCGAL overloads?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> 3D and StraightSkeleton-like SFCGAL-only features are understood.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> Maybe we need to make a case inside ST_3DIntersects that will check<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> ST_IsSolid and choose to call SFCGAL/GEOS depending on what's usually<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> faster, instead of backend switch?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> We have a similar case for Delaunay - it looks like SFCGAL can provide<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> Constrained Delaunay (a proper one that takes lines into account) but GEOS<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> is just much faster on points-only. What if it selected an appropriate<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>> library depending on argument types?<o:p></o:p></span></p><p class=MsoNormal><b><i><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></i></b></p><pre><b><i><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>> </span></i></b>Darafei Praliaskouski<o:p></o:p></pre><p class=MsoNormal><b><i><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></i></b></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'>Here is my second thought after reading both Paul and Darafei.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>I don't want to check ST_IsSolid, want to keep it as a user preference because sometimes as the case in buildings, I don't want to treat my building as solid for intersects checks when Iam doing basic surveying.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>I only care about surface intersects check and prefer the much faster speed of PostGIS native ST_3DIntersects over the more accurate SFCGAL one.<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'>How about we just overload ST_Intesects, ST_3DIntersects and so forth. We love overloading </span><span style='font-size:11.0pt;font-family:Wingdings;color:#1F497D'>J</span><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'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>And then get rid of the backend.<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'>So anyone who wants to use the cgal version would do<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'>ST_Intersects(geom1,geom2, 'cgal')<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'>And geos would be the default.<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'>We only need to do this for:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>ST_3DDistance, ST_3DIntersects, ST_Intersects, ST_Area, 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'>And I doubt few people really want to use cgal for the non-3D variants<o:p></o:p></span></p><p class=MsoNormal><i><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>So the ST_Intersects, ST_Area, ST_Distance are not serious breaking changes<o:p></o:p></span></i></p><p class=MsoNormal><b><i><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></i></b></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Greg is probably screaming now at my horrid attempt at bottom posting.<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'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Regina<o:p></o:p></span></p></div></div></div></body></html>