Hi,
For clarification, it used to be rather a long time ago that the index file
(.qix) was not utilised even it was present in the data folder if the LAYER
DATA was given as
DATA "C:\Data\WMS_DATA.shp"
Index was used only if the LAYER DATA was like
DATA "C:\Data\WMS_DATA"
However, this in old knowledge and both WMS_DATA.shp and WMS_DATA are utilising
the index nowadays.
Gdal is using the same .qix index file system and therefore also QGIS. There is
more info about gdal shapefile spatial index in
http://www.gdal.org/ogr/drv_shapefile.html
The page tells also that native ESRI spatial index files (.sbn/ .sbx) are not
supported.
-Jukka Rahkonen-
________________________________
Lähettäjä: [email protected]
[mailto:[email protected]] Puolesta Ben Madin
Lähetetty: 12. toukokuuta 2011 4:00
Vastaanottaja: [email protected]
Aihe: Re: [mapserver-users] Layer rendering performance problem
I'm not sure whether it is still the case, but it used also to be that
if you wanted to use the index, you need to name the shapefile without the .shp
extension. If you used the .shp extension it wouldn't use the .qix index.
So maybe this is a question - Is that still the case?
On a similar note, does anyone know ... is the index created with
shptree the same as the one created by QGIS (also a .qix file)?
cheers
Ben
On 12/05/2011, at 10:45 AM, [email protected]
wrote:
From: Stephen Woodbridge <[email protected]>
Date: 11 May 2011 11:53:34 PM AWST
To: [email protected]
Subject: Re: [mapserver-users] Layer rendering performance
problem
look at the mapserver utilities:
shptree myshapefile
This creates a spatial index (*.qix) and you should create one
for every shapefile you are using.
On Linux this will do the trick:
find /path/data -name \*.shp -exec shptree {} \;
If the .qix file is missing on every draw mapserver must create
one on the fly in memory and the it throws it away.
-Steve W
On 5/11/2011 11:47 AM, Jon-Paul Dobson wrote:
Hi Jukka,
Thanks for getting back to me so quickly. No I haven't
tried this. How
is this done and what is the benefit? Aren't Shape
files already indexed?
Regards,
Jon-Paul.
On Wed, May 11, 2011 at 4:41 PM, Rahkonen Jukka
<[email protected]
<mailto:[email protected]>> wrote:
Hi,
No answers but a question back. Have you created
spatial index
(.qix) for your shapefiles with shptree?
-Jukka Rahkonen-
Jon-Paul Dobson wrote:
> Hi,
> Whenever I display a layer based on a Shape file
I notice that
the Shape
file is accessed constantly. This makes rendering
extremely slow when
compared to, for example, ESRI ArcIMS which appears
to cache the
Shape file.
Is there an equivalent caching mechanism for Map
Server? ArcIMS seems to
render an order of magnitude faster when the number
of symbols runs
into the
1000s
> Similarly, whenever I display layer symbols using
a truetype font
I notice
that the .ttf file is accessed for every symbol.
This makes rendering
appallingly slow. Is there also any caching
mechanism to prevent this?
> Any insight anyone can give would be much
appreciated.
Best regards,
Jon-Paul.
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