<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body ><div>I guess you can use coalesce to replace the null values with something you want. In your case I think an empty geometry will give you the complete first geometry. </div><div><br></div><div>/Nicklas</div><div><div style="font-size:9px;color:#575757">Skickat från min Samsung Mobil.</div></div><br><br><div>-------- Originalmeddelande --------</div><div>Från: Komяpa <me@komzpa.net> </div><div>Datum:2014-09-02 13:59 (GMT+01:00) </div><div>Till: PostGIS Development Discussion <postgis-devel@lists.osgeo.org> </div><div>Kopia: PostGIS Users Discussion <postgis-users@lists.osgeo.org> </div><div>Rubrik: Re: [postgis-users] [postgis-devel] Is there a reason we don't have an ST_Intersection aggregate function </div><div><br></div><div dir="ltr">There's another thing with ST_Intersection/ST_Difference: sometimes you have to make ST_Difference(geom, (select ST_Union(..,) where ...)) while second operand evaluates to NULL (you shouldn't crop geometry). Currently that leads to ST_Difference pushing out NULL. for my use case, that's not desired semantics - can it be changed?<br>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-09-01 4:16 GMT+03:00 Paragon Corporation <span dir="ltr"><<a href="mailto:lr@pcorp.us" target="_blank">lr@pcorp.us</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I wasn't sure if we just thought there wasn't much utility in it or if there<br>
was a technical obstacle.<br>
<br>
I would think that would be easier to build than the other aggregates since<br>
as you add more geometries it shrinks and the current aggregate state is<br>
always the result of the previous state plus new geometry (so no need for an<br>
accumulation function or a final state function) and if you ever end up with<br>
a geometry collection, you short-circuit out.<br>
<br>
Thanks,<br>
Regina<br>
<br>
<br>
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</blockquote></div><br><br clear="all"><br>-- <br>Darafei "Komяpa" Praliaskouski<br>OSM BY Team - <a href="http://openstreetmap.by/" target="_blank">http://openstreetmap.by/</a><br><a href="mailto:xmpp%3Ame@komzpa.net" target="_blank">xmpp:me@komzpa.net</a> mailto:<a href="mailto:me@komzpa.net" target="_blank">me@komzpa.net</a><br>
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