More Like This Request Handler doesn't return score

[Robert Wenig <rw...@know-center.at>]

I am using Solr to search for "more like this" content. The field which mlt should operate on has normally the length of a sentence. So I am actually searching for mlt sentences.

I have configured a mlt request handler in the solrconfig.xml

<requestHandler name="/mlt" class="solr.MoreLikeThisHandler">

    <str name="mlt.fl">content</str>

    <str name="mlt.mintf">0</str>

    <str name="mlt.mindf">0</str>

  </requestHandler>

The corresponding schema.xml

<schema name="MyAppSchema" version="1.6">



    <field name="content" type="text_mlt" indexed="true" stored="true" required="true" />



    <fieldType name="text_mlt" class="solr.TextField" termVectors="true" >

        <analyzer type="index">

            <tokenizer class="solr.StandardTokenizerFactory"/>

            <filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt" />

            <filter class="solr.LowerCaseFilterFactory"/>

        </analyzer>

        <analyzer type="query">

            <tokenizer class="solr.StandardTokenizerFactory"/>

            <filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt" />

            <filter class="solr.SynonymGraphFilterFactory" synonyms="synonyms.txt" ignoreCase="true" expand="true"/>

            <filter class="solr.LowerCaseFilterFactory"/>

        </analyzer>

    </fieldType>



</schema>

When I am now execute requests against this mlt RequestHandler I get results but without the matching score. Is it possible to return the score too when using the Request Handler?

One example in the documentation displays the score of mlt but only when using the SearchHandler<https://solr.apache.org/guide/8_8/morelikethis.html#search-component-query-and-response>. Should I use the Searchhandler to get the score? Are there any drawbacks when using the SearchHandler over the MLT Request Handler?

Re: More Like This Request Handler doesn't return score

[Alessandro Benedetti <a....@sease.io>]

Hi Robert,
what do you need the score for?
Effectively the score is meaningful just within a query and a result set in
a specific index snapshot
i.e. just useful for debugging purposes

I have been working extensively with this feature, I would recommend using
the MLT query parser, both for debugging purposes to see the query
generated (with the interesting terms) and to return the score.
I have in my *very long* to-do list to add a way to add a probabilistic
score [0-1] for MLT.

Unfortunately, I don't have a quick answer for your problem, I should go
back to investigate why you can not return the score as any other field
with that request handler (fl=score,*).

Cheers
--------------------------
Alessandro Benedetti
Apache Lucene/Solr Committer
Director, R&D Software Engineer, Search Consultant

www.sease.io


On Fri, 18 Jun 2021 at 09:38, Robert Wenig <rw...@know-center.at> wrote:

> I am using Solr to search for "more like this" content. The field which
> mlt should operate on has normally the length of a sentence. So I am
> actually searching for mlt sentences.
>
> I have configured a mlt request handler in the solrconfig.xml
>
> <requestHandler name="/mlt" class="solr.MoreLikeThisHandler">
>
>     <str name="mlt.fl">content</str>
>
>     <str name="mlt.mintf">0</str>
>
>     <str name="mlt.mindf">0</str>
>
>   </requestHandler>
>
> The corresponding schema.xml
>
> <schema name="MyAppSchema" version="1.6">
>
>
>
>     <field name="content" type="text_mlt" indexed="true" stored="true"
> required="true" />
>
>
>
>     <fieldType name="text_mlt" class="solr.TextField" termVectors="true" >
>
>         <analyzer type="index">
>
>             <tokenizer class="solr.StandardTokenizerFactory"/>
>
>             <filter class="solr.StopFilterFactory" ignoreCase="true"
> words="stopwords.txt" />
>
>             <filter class="solr.LowerCaseFilterFactory"/>
>
>         </analyzer>
>
>         <analyzer type="query">
>
>             <tokenizer class="solr.StandardTokenizerFactory"/>
>
>             <filter class="solr.StopFilterFactory" ignoreCase="true"
> words="stopwords.txt" />
>
>             <filter class="solr.SynonymGraphFilterFactory"
> synonyms="synonyms.txt" ignoreCase="true" expand="true"/>
>
>             <filter class="solr.LowerCaseFilterFactory"/>
>
>         </analyzer>
>
>     </fieldType>
>
>
>
> </schema>
>
> When I am now execute requests against this mlt RequestHandler I get
> results but without the matching score. Is it possible to return the score
> too when using the Request Handler?
>
> One example in the documentation displays the score of mlt but only when
> using the SearchHandler<
> https://solr.apache.org/guide/8_8/morelikethis.html#search-component-query-and-response>.
> Should I use the Searchhandler to get the score? Are there any drawbacks
> when using the SearchHandler over the MLT Request Handler?
>
>