[Xapian-discuss] Re: I need a functionset_sort_by_relevance_then_value()

[Sungsoo Kim]

Dear Olly,

Thank you for your prompt reply!
I have already become a admirer of xapian.

You pointed out what I was not aware of.
I have checked up the document to solve my problem.
And thanks to your explanation I could find out easily what I want.

I can set weighting scheme to ignore document length by setting a paramter
such as BM25Weight(0,0,0,0,0). And I will try to modify some functions 
like msetcmp_sort_forward_relevance() in multimatch.cc file in order to
get search results what I want.

I hope you add the function set_sort_by_relevance_then_value() in the
future version of xapian if you think there will be any possibility that the
function can be used by other people.


Many thanks!


Sungsoo Kim



----- Original Message ----- 
From: "Olly Betts" <olly at survex.com>
Newsgroups: gmane.comp.search.xapian.general
Cc: <xapian-discuss at lists.xapian.org>
Sent: Wednesday, March 01, 2006 5:37 AM
Subject: Re: I need a functionset_sort_by_relevance_then_value()


On Wed, Mar 01, 2006 at 04:04:14AM +0900, Sungsoo Kim wrote:
> Without set_sort_by_relevance_then_value() how can I get the same result?

I don't think you can.

But note that for your plan to work you'd need to have all documents
the same length, or you use a weighting scheme which ignores document
length.  That's why sort_by_relevance_then_value isn't implemented -
it's rare for two documents to score exactly the same relevance with
BM25.

Cheers,
    Olly