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From Ron Mayer <r...@0ape.com>
Subject Re: edismax pf2 and ps
Date Fri, 13 Aug 2010 18:38:17 GMT
Yonik Seeley wrote:
> Perhaps a ps2 parameter to match pf2?

That might be nice.

I could try to put together such a patch if people were interested.

One more thing I've been contemplating is if my results might
be even better if I had a couple different "pf2"s with different "ps"'s
at the same time.

In particular.   One with ps=0 to put a high boost on ones the have
the right ordering of words.  For example insuring that:
  "red hat black jacket"
boosts only red hats and not black hats.

And another pf2 with a more modest boost with ps=5 or so to handle
the query above also boosting docs with "red baseball hat".


Not sure of a good way to express that in config options, tho.



> -Yonik
> http://www.lucidimagination.com
> 
> On Fri, Aug 13, 2010 at 2:11 PM, Ron Mayer <rm_g@0ape.com> wrote:
>> Jayendra Patil wrote:
>>> We pretty much had the same issue, ended up customizing the ExtendedDismax
>>> code.
>>>
>>> In your case its just a change of a single line
>>>         addShingledPhraseQueries(query, normalClauses, phraseFields2, 2,
>>>  tiebreaker, pslop);
>>> to
>>>         addShingledPhraseQueries(query, normalClauses, phraseFields2, 2,
>>>  tiebreaker, 0);
>> Thanks!!!  Indeed it seems to be providing better results for me (at first
>> glance on a test system).
>>
>> Is there any way of lobbying to make this change in the official releases?
>>
>>
>>> On Thu, Aug 12, 2010 at 1:04 PM, Ron Mayer <rm_g@0ape.com> wrote:
>>>> Short summary:
>>>>
>>>>   Is there any way I can specify that I want a lot
>>>>   of phrase slop for the "pf" parameter, but none
>>>>   at all for the "pf2" parameter?
>>>>
>>>> I find the 'pf' parameter with a pretty large 'ps' to do a very
>>>> nice job for providing a modest boost to many documents that are
>>>> quite well related to many queries in my system.
>>>>
>>>> In contrast, I find the 'pf2' parameter with zero 'ps' does
>>>> extremely well at providing a high boost to documents that
>>>> are often exactly what someone's searching for.
>>>>
>>>> Is there any way I can get both effects?
>>>>
>>>> Edismax's pf2 parameter is really nice for boosting exact [sub]phrases
>>>> in queries like 'black jacket red cap white shoes'.   But as soon
>>>> as even a little phrase slop (ps) is added, it seems like it starts
>>>> boosting documents with red jackets and white caps just as much as
>>>> those with black jackets and red caps.
>>>>
>>>> My gut feeling is that if I could have "pf" with a large phrase
>>>> slop and the pf2 with zero phrase slop, it'd give me better overall
>>>> results than any single phrase slop setting that gets applied to both.
>>>>
>>>> Is there any good way for me to test that?
>>>>
>>>>  Thanks,
>>>>   Ron
>>>>
>>>>
>>


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