dismax bq

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dismax bq

Jason Rennie-2
I'd like to be able to specify query term weights/boosts, which it sounds
like bq was created for.  I think my understanding from the wiki is a bit
rough, so I'm hoping I might be able to get some questions answered here.
Any thoughts/comments are much appreciated.

I initially tried simply passing a dismax-style query in bq w/ an empty q
param and got no results.  Is this because bq terms must specify fields.
I.e. bq=shoes won't work, but bq=title:shoes will boost docs that match
"shoes" in the "title" field?

Does bq simply add boosts to query terms?  Say my only qf is "title" and
q=boots&bq=shoes^0.5.  Does this translate to a lucene query of
q=title:boots^1.0+title:shoes^0.5.  If, instead, q=shoes+boots, would the
lucene query be q=title:boots^1.0+title:shoes^1.5 ?

Is it possible to negatively boost a term without completely negging it?
I.e. is it possible to do something like q=shoes&bq=bags^-1.0 ?

Thanks,

Jason
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Re: dismax bq

Otis Gospodnetic-2
Jason,
Try boosts less than 1.0 for "negative" boosting.  Use &debugQuery=true to see how your query gets parsed and rewritten.

Otis
---
Sematext -- http://sematext.com/ -- Lucene - Solr - Nutch



----- Original Message ----

> From: Jason Rennie <[hidden email]>
> To: [hidden email]
> Sent: Tuesday, August 5, 2008 10:45:24 AM
> Subject: dismax bq
>
> I'd like to be able to specify query term weights/boosts, which it sounds
> like bq was created for.  I think my understanding from the wiki is a bit
> rough, so I'm hoping I might be able to get some questions answered here.
> Any thoughts/comments are much appreciated.
>
> I initially tried simply passing a dismax-style query in bq w/ an empty q
> param and got no results.  Is this because bq terms must specify fields.
> I.e. bq=shoes won't work, but bq=title:shoes will boost docs that match
> "shoes" in the "title" field?
>
> Does bq simply add boosts to query terms?  Say my only qf is "title" and
> q=boots&bq=shoes^0.5.  Does this translate to a lucene query of
> q=title:boots^1.0+title:shoes^0.5.  If, instead, q=shoes+boots, would the
> lucene query be q=title:boots^1.0+title:shoes^1.5 ?
>
> Is it possible to negatively boost a term without completely negging it?
> I.e. is it possible to do something like q=shoes&bq=bags^-1.0 ?
>
> Thanks,
>
> Jason