How to influence the score in lucene 2.9

[Gregory Tarr <Gr...@detica.com>]

How easy is it to influence the score of search results in lucene 2.9?

The situation is that we have a large number of dated documents that
match the term "john" but we want to return the latest documents when
"john" is the search term.

My solution to this would be to override the score such that the score
is the number of days since 01/01/1970, the latest documents therefore
scoring the highest.

How is this possible in the lucene API?

Thanks

Greg

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Re: How to influence the score in lucene 2.9

[Ian Lea <ia...@gmail.com>]

An alternative, if you want the date to influence rather than
determine the score, is to use document boosting, with the boost value
set small for old docs and high for new docs.  You would probably need
to play to find suitable values.  One problem would be that a doc that
is recent today will be somewhat older tomorrow.

Another option, more complicated but very flexible, is to use CustomScoreQuery.


--
Ian.


On Wed, May 12, 2010 at 6:21 PM, Erick Erickson <er...@gmail.com> wrote:
> Why wouldn't simply sorting by date descending work in this case? If
> you can detect the situation ahead of time that might be simpler.
>
> Do be aware that sorting by date has its own issues if you've stored
> the dates with very fine resolutions (e.g. seconds), but there are
> well-understood ways of dealing with this.
>
> Best
> Erick
>
> On Wed, May 12, 2010 at 1:04 PM, Gregory Tarr <Gr...@detica.com>wrote:
>
>> How easy is it to influence the score of search results in lucene 2.9?
>>
>> The situation is that we have a large number of dated documents that
>> match the term "john" but we want to return the latest documents when
>> "john" is the search term.
>>
>> My solution to this would be to override the score such that the score
>> is the number of days since 01/01/1970, the latest documents therefore
>> scoring the highest.
>>
>> How is this possible in the lucene API?
>>
>> Thanks
>>
>> Greg
>>
>> This message should be regarded as confidential. If you have received this
>> email in error please notify the sender and destroy it immediately.
>> Statements of intent shall only become binding when confirmed in hard copy
>> by an authorised signatory.  The contents of this email may relate to
>> dealings with other companies within the Detica Limited group of companies.
>>
>> Detica Limited is registered in England under No: 1337451.
>>
>> Registered offices: Surrey Research Park, Guildford, Surrey, GU2 7YP,
>> England.
>>
>>
>

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Re: How to influence the score in lucene 2.9

[Erick Erickson <er...@gmail.com>]

Why wouldn't simply sorting by date descending work in this case? If
you can detect the situation ahead of time that might be simpler.

Do be aware that sorting by date has its own issues if you've stored
the dates with very fine resolutions (e.g. seconds), but there are
well-understood ways of dealing with this.

Best
Erick

On Wed, May 12, 2010 at 1:04 PM, Gregory Tarr <Gr...@detica.com>wrote:

> How easy is it to influence the score of search results in lucene 2.9?
>
> The situation is that we have a large number of dated documents that
> match the term "john" but we want to return the latest documents when
> "john" is the search term.
>
> My solution to this would be to override the score such that the score
> is the number of days since 01/01/1970, the latest documents therefore
> scoring the highest.
>
> How is this possible in the lucene API?
>
> Thanks
>
> Greg
>
> This message should be regarded as confidential. If you have received this
> email in error please notify the sender and destroy it immediately.
> Statements of intent shall only become binding when confirmed in hard copy
> by an authorised signatory.  The contents of this email may relate to
> dealings with other companies within the Detica Limited group of companies.
>
> Detica Limited is registered in England under No: 1337451.
>
> Registered offices: Surrey Research Park, Guildford, Surrey, GU2 7YP,
> England.
>
>