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https://issues.apache.org/jira/browse/LUCENE-9418?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17148438#comment-17148438
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ASF subversion and git services commented on LUCENE-9418:
---------------------------------------------------------
Commit 3a42716cdb06ba650ccb2cbc9953c05c9a8a6abc in lucene-solr's branch
refs/heads/branch_8x from Alan Woodward
[ https://gitbox.apache.org/repos/asf?p=lucene-solr.git;h=3a42716 ]
LUCENE-9418: Fix ordered intervals over interleaved terms (#1618)
Given the input text 'A B A C', an ordered interval 'A B C' will currently
return an incorrect
internal [2, 3] in addition to the correct [0, 3] interval. This is due to a
bug in the ORDERED
algorithm, where we assume that after the first interval is returned, the
sub-intervals are
always in-order. This assumption only holds during minimization, as minimizing
an interval
may move the earlier terms beyond the trailing terms.
For example, after the initial [0, 3] interval is found above, the algorithm
will attempt to
minimize it by advancing A to [2,2]. Because this is still before C at [3,3],
but after B at
[1,1], we then try advancing B, leaving it at [Inf,Inf]. Minimization has
failed, so we return
the original interval of [0,3]. However, when we come to retrieve the next
interval, our
subintervals look like this: A[2,2], B[Inf,Inf], C[3,3] - the assumption that
they are in order
is broken. The algorithm sees that A is before B, assumes that therefore all
subsequent
subintervals are in order, and returns the new interval.
This commit fixes things by changing the assumption of ordering to only hold
during
minimization. When first finding a candidate interval, the algorithm now checks
that
all sub-intervals appear in order.
> Ordered intervals can give inaccurate hits on interleaved terms
> ---------------------------------------------------------------
>
> Key: LUCENE-9418
> URL: https://issues.apache.org/jira/browse/LUCENE-9418
> Project: Lucene - Core
> Issue Type: Bug
> Reporter: Alan Woodward
> Assignee: Alan Woodward
> Priority: Major
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Given the text 'A B A C', an ordered interval over 'A B C' will return the
> inaccurate interval [2, 3], due to the way minimization is handled after
> matches are found.
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