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Posted to dev@lucene.apache.org by "Alan Woodward (JIRA)" <ji...@apache.org> on 2018/09/03 12:54:00 UTC
[jira] [Commented] (LUCENE-8477) Improve handling of inner
disjunctions in intervals
[ https://issues.apache.org/jira/browse/LUCENE-8477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16602124#comment-16602124 ]
Alan Woodward commented on LUCENE-8477:
---------------------------------------
I can see a couple of options here:
1) Add a new operator, OR_MAX, which doesn't try to minimize its internals, and sorts prefixes last. This deals with ((a OR (a b)) BLOCK c) mentioned in the description, but it still fails to match in other situations, such as (b OR (b c)) BLOCK c - in this case because (b c) will sort before (b), so the interval will try to match (b c c). It also makes it less easy to use, as consumers now need to understand the semantics of two separate OR operators
2) Allow IntervalsSource to rewrite itself, so that ((a OR (a b)) BLOCK c) becomes (a BLOCK c) OR ((a b) BLOCK c). This would be a lot easier on the user, but I'm not sure how easy it would be from an implementation point of view - it may end up adding lots of extra methods to IntervalsSource.
> Improve handling of inner disjunctions in intervals
> ---------------------------------------------------
>
> Key: LUCENE-8477
> URL: https://issues.apache.org/jira/browse/LUCENE-8477
> Project: Lucene - Core
> Issue Type: New Feature
> Reporter: Alan Woodward
> Priority: Major
>
> The current implementation of the disjunction interval produced by {{Intervals.or}} is a direct implementation of the OR operator from the Vigna paper. This produces minimal intervals, meaning that (a) is preferred over (a b), and (b) also over (a b). This has advantages when it comes to counting intervals for scoring, but also has drawbacks when it comes to matching. For example, a phrase query for ((a OR (a b)) BLOCK (c)) will not match the document (a b c), because (a) will be preferred over (a b), and (a c) does not match.
> This ticket is to discuss the best way of dealing with disjunctions.
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