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<body>Yes,that one I can see.<br />
<br />
About the nearest neighbour I have thought about using st_max_distance against the bounding boxes to find the one with smallest max_distance. That value ought to be good to use in the st_dwithin part of the query. <br />
<br />
Maybe it would even be worth the effort to use st_distance from the geometry found with the "max_distance" boundingbox to usi in in st_dwithin. <br />
<br />
Hope it is possible to understand what I mean. It is at least one release ahead but possible to test :-)<br />
<br />
<br />
/Nicklas<br />
<br />
<span class="content">
<pre><span class="syntax0"><br />
</span></pre></span><br />
2009-07-19 Paragon Corporation wrote:<br />
<br />
>
<div align="left"><span style="font-family: Arial; font-size: 10pt; color: rgb(0, 0, 255);">Windowing functions come in especially handy for nearest
neighbor search getting top n per location. We are going to demonstrate
that in our OSCON conference. Slides and materials will of course will be
available after the conference is over.</span></div><br />
>>
<div align="left">
<hr />
<span style="font-family: Tahoma; font-size: 10pt;"><span style="font-weight: bold;">From:</span>
postgis-devel-bounces@postgis.refractions.net
[mailto:postgis-devel-bounces@postgis.refractions.net] <span style="font-weight: bold;">On Behalf Of
</span>nicklas.aven@jordogskog.no<br />
><span style="font-weight: bold;">Sent:</span> Sunday, July 19, 2009 1:52
PM<br />
><span style="font-weight: bold;">To:</span> PostGIS Development Discussion<br />
><span style="font-weight: bold;">Subject:</span> Re:
[postgis-devel] Caching function calls with CTEs<br />
></span><br />
></div>
>
<div> </div>This is really cool Regina and Leo<br />
><br />
>It's a new way of thinking
for me to to use this recursive thing, but I can see that it is very
useful.<br />
>I hope I will get some time in the near future to try to understand
it better.<br />
><br />
>Also the windowing functions together with postgis aggregate
function will be fun to try.<br />
><br />
>/Nicklas<br />
><br />
><br />
><br />
><br />
><br />
>2009-07-17
Paragon Corporation wrote:<br />
><br />
>Nicklas,<br />
>><br />
>>We tried CTEs against
that annoying issue of functions not being cached in<br />
>>the same row.
Preliminary tests seem to suggest it might be the ideal<br />
>>solution for
this.<br />
>>We suspect it will also be good in many other scenarios where the
planner<br />
>>refuses to use indexes in the right order
etc.<br />
>><br />
>>http://www.postgresonline.com/journal/index.php?/archives/127-guid.html<br />
>><br />
>>We
are going to test with real spatial queries next in preparation for
our<br />
>>OSCON presentation next
week.<br />
>><br />
>>http://en.oreilly.com/oscon2009/public/schedule/detail/7859<br />
>>Sadly
it looks like we probably won't have 1.4 out in time for our<br />
>>presentation
- oh well :(<br />
>><br />
>><br />
>>Anyrate take a look and test with your data
to see if it speeds up your<br />
>>queries.<br />
>><br />
>>L &
R<br />
>><br />
>><br />
>>_______________________________________________<br />
>>postgis-devel
mailing
list<br />
>>postgis-devel@postgis.refractions.net<br />
>>http://postgis.refractions.net/mailman/listinfo/postgis-devel<br />
>><br />
>>
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