David Smiley created LUCENE-5397:
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Summary: Course cacheable spatial filters
Key: LUCENE-5397
URL: https://issues.apache.org/jira/browse/LUCENE-5397
Project: Lucene - Core
Issue Type: Improvement
Components: modules/spatial
Reporter: David Smiley
Sometimes, spatial filter queries aren't very cacheable because they are too
precise (perhaps submitted from a user's mobile phone GPS coords). To make
matters worse, many mobile user's move in-between one query and the next. What
to do? You could simply not cache such queries because it's pointless, or
perhaps we can optimize for this under-the-hood.
The idea here is to pre-compute the resulting set of very-course grid squares,
and make this part of the cacheable filter query (e.g. the Query returned would
probably be a MultiTermQuery or TermsFilter for a Filter). This component of
the solution is designed to produce a filter that is likely a cache-hit,
however it isn't precise enough. Then you could combine it with a precise
spatial query that you don't cache (e.g. Solr LatLonType query).
Ultimately, the change here might simply be under-the-hood smarts in
RecursivePrefixTreeStrategy that returns a query/filter as defined above when
the precision given is clearly very course... but it is probably best to more
explicitly say when this behavior is desired. And if we wanted to *really*
optimize for this case, then a dedicated PrefixTree encoding could be developed
that has overlapping grid squares.
(this is just a TODO idea; I'm not starting on this anytime soon)
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