LUCENE-8563: Remove k1+1 from the numerator of BM25Similarity #511
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javanna
changed the title
jpountz
approved these changes
Nov 29, 2018
lucene/MIGRATE.txt
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| @@ -150,3 +150,11 @@ in order to support ToParent/ToChildBlockJoinQuery. | |||
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| Normalization is now type-safe, with CharFilterFactory#normalize() returning a Reader and | |||
| TokenFilterFactory#normalize() returning a TokenFilter. | |||
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| ## k1+1 constant factor removed from BM25 similarity numerator | |||
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can you append (LUCENE-8563) ## at the end of the line?
lucene/MIGRATE.txt
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| constant factor was removed from the numerator of the scoring formula. | ||
| Ordering of results is preserved unless scores are computed from multiple | ||
| fields using different similarities. The previous behaviour is now exposed | ||
| through the LegacyBM25Similarity class. |
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maybe add that it can be found in the lucene-misc jar?
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yes I wasn't sure how to phrase that. Will add.
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Merged. |
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Patch for https://issues.apache.org/jira/browse/LUCENE-8563.
This PR removes the k1+1 factor from the numerator of
BM25Similarityand adds a newLegacyBM25Similarityunder misc that exposes the old behaviour. Note that I haven't found a way to easily reproduce the previous behaviour in the explain method, so I left that part out ofLegacyBM25Similarityfor now.