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Solr bq vs boost with edismax for recency boosting

I wonder if bq and boost have the same implication ? results ?

Also is it possible to configure it directly in solrConfig.XML ? Meaning instead of using: 

<str name="bf">recip(ms(NOW/DAY,dc.date.issued_tdt),3.16e-12,2.5,0.05)</str>

I would use

<str name="boost">recip(ms(NOW/DAY,dc.date.issued_tdt),3.16e-12,2.5,0.05)</str>

The point is i want to apply a multiplicative boost for the recency. I believe right now it is not strong enough.

Solution

  • "bf" adds itself to "score", while "boost" multiplies the score. How big the implications are depend on the current range the scores.

    Yes, you can save them like that in solrconfig.xml. And you can easily play with the numbers by adding &bf=recip(ms(NOW/DAY,dc.date.issued_tdt),3.16e-12,2.5,0.05) or &boost=recip(... to your solr query. The values in solrconfig.xml won't be used then.

    For more details on how the score is calculated, you can add &debugQuery=true&enableElevation=true&debug.explain.structured=true to the solr query