[Mapserver-users] Performance of indexed shape files (W2K/php_mapscript)
ujunge at pmcentral.com
ujunge at pmcentral.com
Sun Mar 7 23:36:10 EST 2004
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Hello MapServer Users,
I do not see any performance differences using shapefile indexes, =
generated by precompiled shptree.exe (8/6/2003).
In fact, no matter which command line parameters have been choosen,=20
shapefiles will not render faster nor slower if the qix-file is =
present or not.=20
It doesn't even make a difference what shape-file I'am looking at.
For example, taking a 50MB shape file (200K lines) with street data =
covering CA or TX and zooming in=20
about 1 mile in any city takes exactly the same rendering time, with or =
without qix-files.
As another example, a 80MB filled polygon layer (16K polygons), =
displaying urban-areas and covering the entire US,=20
takes the same time to render (zooing in about 30miles), again with or =
without index-files.
With respect to the performance difference,
- it doesn't matter, if the map for a specific area is requested the =
first time=20
or requested subsequently with small area-hanges .
- it dosen't matter, if only one layer is requested, or more layers, =
which may not be indexed.
All layers have the same projection (WGS84) , the is no reprojection on =
the fly.
Does it mean, that the qix-index is not used at all ?
Is this a Windows - Distribution issue ? (i would like to use Linux, but =
the customer not)
I use the precomiled php_mapscript_40.dll (8/5/2003) on a PIII =
W2K-Server (512MB) .
Greetings,
Uwe Junge
Uwe Junge
PMCentral Systems, Inc.
4201 Pinefield Court
Fairfax, Virginia 22033
(703) 378-0952
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<DIV><FONT face=3DArial size=3D2>
<DIV><FONT face=3DArial size=3D2>Hello MapServer Users,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I do not see any performance =
differences using=20
shapefile indexes, generated by precompiled shptree.exe =
(8/6/2003).</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>In fact, no matter which command=20
line parameters have been choosen, </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>shapefiles will not render faster nor =
slower =20
if </FONT><FONT face=3DArial size=3D2>the qix-file is present or =
not.=20
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>It doesn't even make a difference what=20
shape-file I'am looking at.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>For example, taking a 50MB shape =
file (200K=20
lines) with street data </FONT><FONT face=3DArial size=3D2>covering CA =
or TX and=20
zooming in </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>about 1 mile in any city takes exactly =
the same=20
rendering time, with or without qix-files.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>As another example, a 80MB filled =
polygon layer=20
(16K polygons), displaying urban-areas and covering the entire US, =
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>takes the same time to render (zooing =
in about=20
30miles), again with or without index-files.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>With respect to the performance=20
difference,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>- it doesn't matter, if =
the map for a=20
specific area is requested the first time </FONT></DIV>
<DIV><FONT face=3DArial size=3D2> or requested=20
subsequently with small area-hanges .</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>- it dosen't matter, if only one layer =
is=20
requested, or more layers, which may not be indexed.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>All layers have the same projection =
(WGS84) , the=20
is no reprojection on the fly.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Does it mean, that the qix-index is not =
used at all=20
?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Is this a Windows - Distribution issue =
?=20
(</FONT><FONT face=3DArial size=3D2>i would like to use Linux, but the =
customer=20
not)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I use the =
precomiled php_mapscript_40.dll=20
(8/5/2003) on a PIII W2K-Server (512MB) .</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Greetings,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Uwe Junge</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Uwe Junge<BR>PMCentral Systems, =
Inc.<BR>4201=20
Pinefield Court<BR>Fairfax, Virginia 22033</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>(703) 378-0952</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2><BR>---<BR>Outgoing mail is certified =
Virus=20
Free.<BR>Checked by AVG anti-virus system (<A=20
href=3D"http://www.grisoft.com">http://www.grisoft.com</A>).<BR>Version: =
6.0.613 /=20
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3/4/2004</FONT></DIV></FONT></DIV></BODY></HTML>
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