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From: Vadim Gindin <vgindin@detectum.com>
Date: Mon, 4 Dec 2017 15:10:26 +0500
Message-ID: <CADitDkkJhe=aoMbogpQU5wqcWrGw4T0zeFwxp4fNzt8cv_MoHQ@mail.gmail.com>
Subject: Re: Scorer.iterator() - how to implement correctly
To: java-user@lucene.apache.org
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archived-at: Mon, 04 Dec 2017 10:10:33 -0000

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Adrien.

I've found some working solution. Here is how it calculates iterator:

this.iterator =3D context.reader().postings(query.getTerm(), PostingsEnum.A=
LL);
if (this.iterator =3D=3D null) this.iterator =3D DocIdSetIterator.empty();


Is that implementation correct?

On Sun, Dec 3, 2017 at 4:43 PM, Vadim Gindin <vgindin@detectum.com> wrote:

> Hi Adrien.
>
> ConstantScoreQuery - I'd tried that earlier. There is the problem. It
> returns score =3D 0.0 for my configuration with Boolean.. I've debugged a=
nd
> found, that it happens because of the following:
>
> @Override
> public Weight createWeight(IndexSearcher searcher, boolean needsScores, f=
loat boost) throws IOException {
>   final Weight innerWeight =3D searcher.createWeight(query, false, 1f);
>   if (needsScores) {
>     return new ConstantScoreWeight(this, boost) {
>
>
> As you can see innerWeight is created with needsScores=3Dfalse  and furth=
er
> innerWeight.scorerSuplier will return null. That will lead to 0.0 final
> score.
>
> Moreover I'm trying to start my current logic from simple step. That's wh=
y
> I wanted to implement something simple and decide to write it from scratc=
h.
>
> Ok, as you say - iterator is the reason of returning all documents. *So
> how to properly implement scorer.iterator()?*
>
> Many thanks for your help!
> Regards
> Vadim Gindin
>
> On Fri, Dec 1, 2017 at 1:11 PM, Adrien Grand <jpountz@gmail.com> wrote:
>
>> There are many implementations because each query typically needs a cust=
om
>> DocIdSetIterator implementation. It looks like your use-case doesn't nee=
d
>> a
>> custom query though, you could use a TermQuery wrapped in a constant-sco=
re
>> query (see my reply to the other question you asked).
>>
>> Le ven. 1 d=C3=A9c. 2017 =C3=A0 08:24, Vadim Gindin <vgindin@detectum.co=
m> a =C3=A9crit
>> :
>>
>> > Hi
>> >
>> > I'm implementing the custom QUERY with appropriate custom WEIGHT and
>> > SCORER.
>> >
>> > I'm trying to implement Scorer.iterator() method. It should return an
>> > iterator of documents that matches the query. Right? There are a lot o=
f
>> > descendant classes of the DocIdSetIterato.
>> >
>> > 1. How to choose correct one?
>> > 2. How to correctly implement Scorer.iterator() method?
>> >
>> > I've tried DocIdSetIterator.all(context.reader().maxDoc());
>> >
>> > But as I can see it returns all documents.
>> >
>> > My task looks simple. I need to return a constant score depending on t=
he
>> > matched fields. I.e. field "model" score - 3f, field "vendor" - score =
-
>> 5f.
>> >
>> > I'm creating a subquery for each field and specify score for it using
>> > custom QUERY that is almost the same as TermQuery except Weight.Scorer
>> >
>> > Any help is appreciated.
>> >
>> > Regards,
>> > Vadim Gindin
>> >
>>
>
>

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