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#263 Galago: BM25 does not work with Maxscore

v1.x
accepted
1
2015-12-07
2015-05-26
John Foley
No

Perhaps this is the root of its "terrible" performance. (mAP ~= 0.08)

Workaround:--processingModel=rankeddocument in Retrieval or Query Parameters.

Discussion

  • John Foley

    John Foley - 2015-05-26
    • status: open --> accepted
    • assigned_to: John Foley
     
  • John Foley

    John Foley - 2015-05-26

    For now, BM25 no longer implements MaxScore. The underlying issue with its implementation is still not fixed, but unless there's a need for better performance with this model, commenting it out is at least solution for the upcoming 3.8 release.

     
  • John Foley

    John Foley - 2015-12-07

    The real issue here is that bm25 is a scoring operator, so it should only have one children, and be repeated for all its children. The low map we're seeing is because Galago hides the error and runs single term queries instead of the whole query!

    This is a bug, and Galago ought to crash if it gets a bm25 node with multiple text children.

     

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