<html><head><style>body{font-family:Helvetica,Arial;font-size:13px}</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">Right, but empty != null, and doesn’t obey null semantics.</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">Basic example,</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">ST_Union(polygon,empty) = polygon</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">Semantically, empty is closer to zero than to null.</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">Anyways, in this *particular* example, I’m not sure that null is better than error. In either case a condition probably has to be trapped, either the incoming empty to stop and error, or the outgoing null, to stop a null propagation.</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">P.</div> <div id="bloop_sign_1405089027845246976" class="bloop_sign"><div><br></div><span style="font-family:helvetica,arial;font-size:13px"></span>-- <br>Paul Ramsey<br>http://cleverelephant.ca<div>http://postgis.net</div></div> <br><p style="color:#000;">On July 11, 2014 at 1:11:40 AM, Rémi Cura (<a href="mailto:remi.cura@gmail.com">remi.cura@gmail.com</a>) wrote:</p> <blockquote type="cite" class="clean_bq"><span><div><div></div><div>
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<div>Not willing to put a fight,<br></div>
but I think the standard behaviour for logic of (TRUE,FALSE,NULL)
in postgres is whatever involves NULL is NULL.<br></div>
<div>By extending this concept to null geom, one should expect a
null output.<br>
And i don't feel it should be this function that forces you to take
special care of empty geometry.<br></div>
<div>If you are worried about empty geometry for your special case,
you can still filter it befor or after (with a where result is not
null on result ! )<br>
<br></div>
<div>That being said, I don't see major interest in empty geom
instead of null ..<br></div>
<div>Cheers,<br>
Rémi-C<br></div>
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Cheers,<br>
Rémi-C<br>
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<div class="gmail_extra"><br>
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<div class="gmail_quote">2014-07-10 23:31 GMT+02:00 Sandro Santilli
<span dir="ltr"><<a href="mailto:strk@keybit.net" target="_blank">strk@keybit.net</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div class="">On Thu, Jul 10, 2014 at 01:45:49PM -0400, Paragon
Corporation wrote:<br>
> or Empty happy. It should be a POINT EMPTY of course :)<br>
<br></div>
ST_LineLocatePoint retuns a floating point number between 0 and
1.<br>
<br>
--strk;<br>
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