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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Marc,</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Would the following work: box2d(transform(
extent(wkb_geometry), 4326) )</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I think that you will achieve an
efficiency from the following points:</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<ol start=1 type=1>
<li class=MsoNormal style='color:navy'><font size=2 color=navy face=Arial><span
style='font-size:10.0pt;font-family:Arial'>you should not need to collect,
if all you want is the bounding box, since extent() should give you that</span></font></li>
<li class=MsoNormal style='color:navy'><font size=2 color=navy face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Even if you DO have to use
collect, you will save lots of computation time by doing the transform on
the final aggregate (1 transform), rather than for every record (100,000 transforms).</span></font></li>
</ol>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<div>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Robert W. Burgholzer</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Surface Water Modeler</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Office of Water Supply and Planning</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Virginia Department of Environmental
Quality</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><a
href="mailto:rwburgholzer@deq.virginia.gov">rwburgholzer@deq.virginia.gov</a></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>804-698-4405</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Open Source Modeling Tools:</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><a
href="http://sourceforge.net/projects/npsource/">http://sourceforge.net/projects/npsource/</a></span></font></p>
</div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma'>-----Original Message-----<br>
<b><span style='font-weight:bold'>From:</span></b>
postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Marc Jacquin<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, June 30, 2008 9:23
AM<br>
<b><span style='font-weight:bold'>To:</span></b> '</span></font><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>PostGIS Users
Discussion</span></font><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma'>'<br>
<b><span style='font-weight:bold'>Subject:</span></b> [postgis-users]
Collecting points for the overall bounding box </span></font></p>
<p class=MsoNormal style='margin-left:.5in'><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'> </span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'>Hi all,</span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'> </span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'>The request is quite simple, something like:</span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'> </span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'>SELECT box2d(collect(transform(wkb_geometry,4326)))
FROM mytable</span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'> </span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'>Mytable contains about 100000 records of a point type
geometry. A GIST index is available for the table but it takes <b><span
style='font-weight:bold'>several minutes</span></b> on a respectable recent
dual-core with 4 Gb of RAM. </span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'> </span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'>Any idea would be helpful.</span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'> </span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'>Thx.</span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'> </span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'>Marc</span></font></p>
<p class=MsoPlainText style='margin-left:.5in'><font size=2 face="Courier New"><span
style='font-size:10.0pt'> </span></font></p>
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