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Posted to dev@lucene.apache.org by "David Smiley (JIRA)" <ji...@apache.org> on 2013/04/08 17:15:16 UTC
[jira] [Updated] (LUCENE-4916) Spatial WithinPrefixTreeFilter can
too eagerly find false-positive
[ https://issues.apache.org/jira/browse/LUCENE-4916?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
David Smiley updated LUCENE-4916:
---------------------------------
Attachment: LUCENE-4916__Spatial_Within_RPT_and_shape_simplification.patch
The attached patch fixes this issue, and includes a testcase. The approach has room for further optimization.
Although unrelated, I found it possible for AbstractVisitingPrefixTreeFilter to have a minimum configurable scan level of 0 (formerly 1). I made this change too; it enabled the aforementioned test to be a little more thorough.
> Spatial WithinPrefixTreeFilter can too eagerly find false-positive
> -------------------------------------------------------------------
>
> Key: LUCENE-4916
> URL: https://issues.apache.org/jira/browse/LUCENE-4916
> Project: Lucene - Core
> Issue Type: Bug
> Components: modules/spatial
> Reporter: David Smiley
> Assignee: David Smiley
> Priority: Minor
> Attachments: LUCENE-4916__Spatial_Within_RPT_and_shape_simplification.patch
>
>
> The recently committed WithinPrefixTreeFilter can sometimes match a false-positive due to the grid approximation technique. Some of this is normal. But if an indexed shape has any of its leaf detail levels "simplified" (removed) up to a higher level, then a false-positive match can occur that is a little too eager when one of those cells that were simplified-away don't intersect the query shape, and thus shouldn't be considered a match for this predicate.
> Marking as "Minor" because it should be quite rare, and when it does occur, the answer (a match) will usually appear close-enough due to the grid approximation that it's not a totally inaccurate answer. I found this problem via extensive randomized testing. I want to fix it because it should make my new tests pass :-)
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