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https://issues.apache.org/jira/browse/LUCENE-4978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13649007#comment-13649007
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David Smiley commented on LUCENE-4978:
--------------------------------------
The offending code is the implementation of IntersectsPrefixTreeFilter's
VisitorTemplate.visitScanned:
{code:java}
if (cell.getLevel() == grid.getMaxLevels() && !cell.isLeaf())
cShape = cell.getCenter();
else
cShape = cell.getShape();
if (queryShape.relate(cShape).intersects())
collectDocs(results);
{code}
What's going on here is a performance optimization to use a point for the
intersection instead of a rectangle. I never measured the before-after effect,
and I'm not sure if I even thought of it in terms of a performance optimization
in the first place although that's what it is.
One possible solution is to see if the query shape is a rectangle or circle; if
so then buffer the query shape by 1/2 a grid cell, which is enough to eliminate
the possibility of a false-negative. If it's another shape (whether it be a
point or a polygon) then use the cell's rect instead of its center point.
> Spatial search with point query won't find identical indexed point
> ------------------------------------------------------------------
>
> Key: LUCENE-4978
> URL: https://issues.apache.org/jira/browse/LUCENE-4978
> Project: Lucene - Core
> Issue Type: Bug
> Components: modules/spatial
> Affects Versions: 4.1
> Reporter: David Smiley
> Assignee: David Smiley
> Priority: Minor
>
> Given a document with indexed POINT (10 20), when a search for INTERSECTS(
> POINT (10 20)) is issued, no results are returned.
> The work-around is to not search with a point shape, use a very small-radius
> circle or rectangle. (I'm marking this issue as "minor" because it's easy to
> do this).
> An unstated objective of the PrefixTree/grid approximation is that no matter
> what precision you use, an intersects query will find all true-positives.
> Due to approximations, it may also find some close false-positives. But in
> the case above, that unstated promise is violated. But it can also happen
> for query shapes other than points which do in fact barely enclose the point
> given at index time yet the indexed point is in-effect shifted to the center
> point of a cell which could be outside the query shape, and ultimately
> leading to a false-negative.
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