[mapserver-users] Layer rendering performance problem

[Rahkonen Jukka]

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: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] Puolesta Ben Madin
	Lähetetty: 12. toukokuuta 2011 4:00
	Vastaanottaja: mapserver-users at lists.osgeo.org
	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, mapserver-users-request at lists.osgeo.org wrote:


		
		From: Stephen Woodbridge <woodbri at swoodbridge.com>
		
		Date: 11 May 2011 11:53:34 PM AWST
		
		To: mapserver-users at lists.osgeo.org
		
		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
			

			<Jukka.Rahkonen at mmmtike.fi <mailto:Jukka.Rahkonen at mmmtike.fi>> 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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