Angel, Eric wrote:
> Is there a performance difference between using CQL vs creating your own
> filters?
>
There are three ways to produce a Filter; they all produce the same object:
1. FilterFactory2 is fast; you as the programmer are saying exactly what
you mean
2. CQL has the overhead of a lexer and parser to turn your String into a
series of FilterFactory2 calls
3. Filter XML has the over head of SAX (and sometimes DOM or a GTXML
parser) to turn your document into a series of FilterFactory2 calls
> I'm currently using the below code and it's really slow.
>
> ---------------
> FilterFactory2 ff2 =
> CommonFactoryFinder.getFilterFactory2(GeoTools.getDefaultHints());
> Expression stateProperty = ff2.property("STATE");
> Expression stateValue = ff2.literal(statecode);
> Filter stateFilter = ff2.equals(stateProperty, stateValue);
>
> Filter nameFilter = ff2.equal(ff2.property("NAME"),
> ff2.literal(cityname), false);
> geoFilter = ff2.and(stateFilter, nameFilter);
>
> FeatureSource featureSource =
> ds.getFeatureSource(ds.getTypeNames()[0]);
> FeatureCollection featureCollection =
> featureSource.getFeatures(geoFilter);
> FeatureIterator iterator = featureCollection.features();
> -----------------
>
> Is there a better way to do this if I'm doing this thousands of times per
> minute?
>
That does not sound two sane; Things to try ...
1. using a FeatureID filter; it makes use of an identifier generated by
the DataStore you are using; for a Shapefile this will be the row id and
it will be able to make a couple calls; rather than go through and test
ever feature. For a database this will end up using the primary key etc...
2. Related to the above: If you only expect one result indicate that in
the query as max results value of 1, also you should only make use of
the attributes you need; if you don't need any attributes at all
shapefile will be able to find you a geometry must faster
3. If your data is small enough load it into a MemoryDataStore; that
will store the fetaures in a TreeSet organized by FeatureID (so you can
use the FeatureId filters very quickly)
Jody
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