[Xapian-discuss] Making SORTAFTER useful in omega?

[Arjen van der Meijden]

You're probably right. But I'm not too proficient in C++ and the inner 
workings of Xapian. I already found the place in omega where to alter 
the weighting-scheme in query.cc, and did try changing it to the 
TradWeight-scheme. But that didn't help much.
So what can I change to actually have results that get same scores when 
they would have gotten almost the same scores from BM25/TradWeight?

Do I have to roll my own weighting scheme? Or are there settings for 
BM25 or TradWeight that already provide such a result set?

Best regards,

Arjen

On 12-9-2008 2:13 alexander lind wrote:
> Ah, I did misunderstand you there, I thought you wanted to sort the 
> entire relevance set after a date.
> 
> I don't think there is a way to make SORTAFTER less sensitive to small 
> differences in the relevance score. Except for by hacking it in yourself :/
> 
> Alec
> 
> On Sep 11, 2008, at 11:35 AM, Arjen van der Meijden wrote:
> 
>> Alec,
>>
>> I don't really understand your answer or perhaps you didn't understand 
>> my question.
>> I want relevance sort. But when two results are more or less similar 
>> in terms of relevance, I want the newest first (which can indeed be 
>> supplied with a value).
>>
>> This is actually what the SORTAFTER in omega is for. But the chance of 
>> two results having the same relevance is almost zero, so in practice 
>> it doesn't work.
>>
>> Best regards,
>>
>> Arjen
>>
>> On 11-9-2008 17:39 alexander lind wrote:
>>> Can't you just use the reordering parameter 'SORT' to sort on a value 
>>> number?  In this a value number where you'd have put the dates that 
>>> your users wants to sort by?
>>> Alec
>>> On Sep 11, 2008, at 7:12 AM, Arjen van der Meijden wrote:
>>>> Is there no one with some input on this issue?
>>>>
>>>> Best regards,
>>>>
>>>> Arjen
>>>>
>>>> On 1-9-2008 22:43 Arjen van der Meijden wrote:
>>>>> Hello List,
>>>>>
>>>>> Our users keep asking for some more "logical" sorting of search 
>>>>> results.
>>>>> Now the results are sorted on relevance, i.e. the raw weight, by
>>>>> default. But since the users only see the percentage, that results 
>>>>> in a
>>>>> seemingly random secondary sorting.
>>>>>
>>>>> According to the docs and earlier mails, omega has the 'SORTAFTER' 
>>>>> (and
>>>>> docid sorting) functionality to allow date-based secondary sorting. 
>>>>> But
>>>>> according to later mails and the documentation that's only useful 
>>>>> if you
>>>>> don't use the default BM25-weighting. Unfortunately you can't alter 
>>>>> the
>>>>> weighting scheme via Omega-calls.
>>>>> Nor does it seem to help to simply patch query.cc to use TradWeight
>>>>> rather than BM25.
>>>>>
>>>>> Since we've built our set-up around omega, we'd rather not have to 
>>>>> build
>>>>> something similar or patch omega just because its missing a small but
>>>>> important feature. Is it somehow possible to make the newer results in
>>>>> the seemingly similarly relevant results sort on top within Omega?
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Arjen
>>>>>
>>>>> _______________________________________________
>>>>> Xapian-discuss mailing list
>>>>> Xapian-discuss at lists.xapian.org
>>>>> http://lists.xapian.org/mailman/listinfo/xapian-discuss
>>>>>
>>>>
>>>> _______________________________________________
>>>> Xapian-discuss mailing list
>>>> Xapian-discuss at lists.xapian.org
>>>> http://lists.xapian.org/mailman/listinfo/xapian-discuss
> 
>