On 23/02/2011 8:06 AM, Stephan Holl wrote:
Hello Assefa,
Yewondwossen Assefa<[email protected]>, [20110223 - 07:26:34]
Hi Stephan,
On 22/02/2011 3:44 AM, Stephan Holl wrote:
Hello list,
while playing with MapServer WFS Filter Encoding capabilities I
found some strange things when it comes to form the DB-queries (the
requested layer is PostGIS-driven).
It seems that there will always be a full table-scan and later on
the FE will be applied. Is this done by design?
Filters that do include spatial filters end up using the mapserver
experssions. 'Simple' filters should end be using traslated into the
layer's filter expression and end up being used by postgis as part of
the data selection. What does the filter encoding looks like?
It is not a spatial-filter we use currently. It is an attribute-based
IsLike-Filter like seen here[1], but we use it with POST. So adding a
BBOX-related filter as another AND-filter will result in optimized
SQL-Query with only the subset fetched from the database? If so, this
seems worth to document though.
The filter you sent as example should use the layer's filter element
and that should be used when retrieving the data at the postgis level.
When the layer is in debug mode, MapServer 5.6.x logs in this case
shows something like (which indicates that the filter is used at the
postgis level)
...
msPostGISLayerWhichShapes query: select .... and ( (NAME like 'Syd%'
escape '!') )
...
Don't you get similar logs?
Best
Stephan
[1]
http://demo.mapserver.org/cgi-bin/wfs?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=cities&Filter=%3CFilter%3E%3CPropertyIsLike%20wildcard=%27*%27%20singleChar=%27.%27%20escape=%27!%27%3E%3CPropertyName%3ENAME%3C/PropertyName%3E%3CLiteral%3ESyd*%3C/Literal%3E%3C/PropertyIsLike%3E%3C/Filter%3E
--
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Assefa Yewondwossen
Software Analyst
Email: [email protected]
http://www.dmsolutions.ca/
Phone: (613) 565-5056 (ext 14)
Fax: (613) 565-0925
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