Details
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Improvement
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Status: Open
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Major
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Resolution: Unresolved
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8.0
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None
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None
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None
Description
As Doug Turnbull pointed out on the solr-user mailing list: https://lists.apache.org/thread.html/27590a2d8598be515b24f47f7912e074d2010910242cfdeb1fcd655d%40%3Csolr-user.lucene.apache.org%3E (recommended reading, especially for his discussion of the limitations of the new sow=false request parameter), sow=false changes the queries edismax produces over multiple fields when any of the fields’ query-time analysis differs from the other fields’, e.g. if one field’s analyzer removes stopwords when another field’s doesn’t. In this case, rather than a dismax-query-per-whitespace-separated-term (edismax’s behavior when sow=true), a dismax query per field is produced. This can change results in general, but quite significantly when combined with the mm (min-should-match) request parameter: since min-should-match applies per field instead of per term, missing terms in one field’s analysis won’t disqualify docs from matching. E.g. query “Terminator 100” with request param “mm=100%” against both a title (text) field and a run_length (integer) field will result in the following queries:
When sow=true:
+(DisjunctionMaxQuery((title:terminator)) DisjunctionMaxQuery((run_length:[100 TO 100] | title:100)))~2
When sow=false:
+DisjunctionMaxQuery((run_length:[100 TO 100] | ((title:terminator title:100)~2)))
In the above scenario, when sow=true (and in versions of Solr before 6.5), “terminator” must appear in documents in order to produce a match. But when sow=false, a document can match if its run_length field is 100, even when the title does not contain “terminator”.
It is good to have an option to force term centric or query-centric matching at query parsing; so that expected behavior can be achieved; discussed under http://lucene.472066.n3.nabble.com/Split-on-whitespace-parameter-doubt-td4404185.html.
Attachments
Issue Links
- is related to
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SOLR-15407 eDismax sow=false doesn't work with string field types
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- Open
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- Open
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