On Fri, Nov 22, 2013 at 5:42 PM, Gabriel Roldan <[email protected]>wrote:
> Hey there,
>
> It looks to me like the shapefile datastore does not support paging
> through query's startIndex and maxFeatures. It does support maxFeatures
> though.
> So before getting more into it, I just wanted to confirm it doesn't
> support startIndex and ask whether there's a compelling reason for it. I
> may try to come up with a patch otherwise.
>
In the following I assume you're talking about the shapefile code in 10.x
onwards.
ShapefileFeatureSource does not, in fact, override canOffset and canLimit,
so you're right there is not _native_ support for paging,
meaning the performance could be improved with some direct support.
That said, ContentFeatureSource should properly handle paging by skipping
features and limiting results, of course, at a cost.
Thinking about the implementation... hum... not sure it's possible to do
any optimization when filters are around.
Most of the filters cannot be resolved directly before reading, one has to
read features, then check if they match the
filter, which pretty much means you have to read all features anyways to
find those that match the filters.
Even spatial filters cannot be actually run against the spatial index,
which gives us a superset of the actual result.
Cheers
Andrea
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