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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hi list,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>This is my first post so, Hello from Madeira Is. !! </span></font><font
size=2 face=Wingdings><span lang=EN-GB style='font-size:10.0pt;font-family:
Wingdings'>J</span></font><font size=2 face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Now, I’ve been developing a fleet-tracking
application and using (of course) pgsql/postgis.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>To be specific with my dilemma:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>I want to search for the road closest to a vehicle’s
current coordinates, and I want to give a radius in *<b><span style='font-weight:
bold'>meters</span></b>*.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>The road’s layer is in WGS84 as well as the
current vehicle’s coordinates, so I have to reproject on the fly to a
datum that allows me to work in metres; in this case WGS84 / UTM zone 28N.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>So here’s the query:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>select name, city from rede_estradas where <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>transform(geometry,32628) &&
setsrid(expand(transform(geomfromtext('POINT(-16.851888
32.646385)',4326),32628), 5), 32628) <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>and distance(transform(geomfromtext('POINT(-16.851888
32.646385)',4326),32628), transform(geometry,32628)) <=5 limit 1;<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Well… it ‘werks’… *<b><span
style='font-weight:bold'>but</span></b>*! It takes ~1600ms to retrieve the
result… </span></font><font size=2 face=Wingdings><span lang=EN-GB
style='font-size:10.0pt;font-family:Wingdings'>L</span></font><font size=2
face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'> imagine
this for a fleet of, say, 500 vehicles…<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>I’m using Gist on the geometry column and VACCUM
ANALYZEd the table.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>So, any of you Postgis gurus could point me to a way
to speed up this query?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Any help/info would be greatly appreciated!<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>Best regards,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><u><font size=5 color="#0080c0" face="Bauhaus 93"><span
lang=EN-GB style='font-size:18.0pt;font-family:"Bauhaus 93";color:#0080C0'>Pedro
Doria Meunier</span></font></u><span lang=EN-GB><o:p></o:p></span></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>(351) 91 302 49 72 - (351) 96 247 99 12</span></font><span
lang=EN-GB><o:p></o:p></span></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'>MSN - </span></font><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'><a href="mailto:pdoriam@hotmail.com"><span
lang=EN-GB>pdoriam@hotmail.</span>com</a></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>ICQ - 308-182-126<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Skype: pdoriam</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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