On 06/12/2013 14:23, Kralidis,Tom [Ontario] wrote:
Hi: we have a MapServer OWS instance which we use to disseminate observations via WMS and WFS/SOS.One of our layers has 1 million records (PostGIS backend). The layer has CLASS level EXPRESSION objects for WMS visualization/classification. We initially implemented a LAYER level FILTER, however we have use cases to serve the same layer (with the same identifier) via WFS, in which case we'd like all the data to be available. Our problem happens when visualizing via WMS. We have a Boolean column in our PostGIS table ('latest_observation') which allows us to filter easily to visualize latest observations, which is our desired WMS default. Because we have defined CLASS level filters, the WMS GetMap request is first querying and fetching all records and _then_ applying CLASS level filters (which all include 'latest_observation=1'. So this ends up hurting us performance wise. We'd like to have this filter at the query level so that less members are passed back from the SQL query. When we do a LAYER.FILTER with latest_observation=1, the result is instant (beautiful!). But if we put a LAYER.FILTER, this constrains the data access from the WFS perspective against the same LAYER def. Is there any way to apply a LAYER.FILTER type approach to work _just_ in WMS mode? We'd like all the data in WFS mode. I know we can duplicate the LAYER object as a workaround, but from a data management perspective we'd rather now. I hope I have explained this clearly enough. Any suggestions?
It may seems strange (?), but there is nothing in the WMS spec to filter a WMS layer (that's why Geoserver has CQL filters), and I think the "OGC way" to filter a WMS request is through an SLD stylesheet (which can be generated dynamically).
Thanks ..Tom _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
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