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https://issues.apache.org/jira/browse/LUCENE-4942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13900563#comment-13900563
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David Smiley commented on LUCENE-4942:
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Somewhat related to this is my newfound realization that indexed non-point
shapes will result in IntersectsPrefixTreeFilter (technically it's actually
VisitorTemplate) scanning over these smallest grid cells / terms *twice* and
thus calculate intersection *twice* -- once with the leaf flag, once without.
This is likely a major performance bug. It would be awkward to fix that right
now, but it would be easy once there simply wasn't this redundant indexing of
terms -- hence this issue.
> Indexed non-point shapes index excessive terms
> ----------------------------------------------
>
> Key: LUCENE-4942
> URL: https://issues.apache.org/jira/browse/LUCENE-4942
> Project: Lucene - Core
> Issue Type: Improvement
> Components: modules/spatial
> Reporter: David Smiley
>
> Indexed non-point shapes are comprised of a set of terms that represent grid
> cells. Cells completely within the shape or cells on the intersecting edge
> that are at the maximum detail depth being indexed for the shape are denoted
> as "leaf" cells. Such cells have a trailing '\+' at the end. _Such tokens
> are actually indexed twice_, one with the leaf byte and one without.
> The TermQuery based PrefixTree Strategy doesn't consider the notion of 'leaf'
> cells and so the tokens with '+' are completely redundant.
> The Recursive [algorithm] based PrefixTree Strategy better supports correct
> search of indexed non-point shapes than TermQuery does and the distinction is
> relevant. However, the foundational search algorithms used by this strategy
> (Intersects & Contains; the other 2 are based on these) could each be
> upgraded to deal with this correctly. Not trivial but very doable.
> In the end, spatial non-point indexes can probably be trimmed my ~40% by
> doing this.
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