Solr boost query by field value and inside newest date - sorting

Question

We have the following setup in our schema.xml:
<field name="last_modified" type="date" indexed="true" stored="true" multiValued="false" omitTermFreqAndPositions="true"/>
...
<field name="prefix" type="string" indexed="true" stored="true" omitTermFreqAndPositions="true"/>
Our goal is to sort the docs by
prefix=9999 with newest docs (last modified) first
prefix=1004 or prefix=1005 with newest docs (last modified) first
Our code:
{!boost b=recip(ms(NOW,last_modified),3.16e11,1,1)}prefix:9999^1000000 OR {!boost b=recip(ms(NOW,last_modified),3.16e-11,1,1)}prefix:1004^600000 OR {!boost b=recip(ms(NOW,last_modified),3.16e-11,1,1)}prefix:1005^600000
Result:
The query above does not work as expected!
We thought that omitTermFreqAndPositions=true will force to prevent ITF and the scoring should work. But it does not seem so!
Please help us with this :-)

Answer 1

So we found a solution!
Create your own Similarity (a simple java class)
For a better and simpler descriptions how, please read How to compile a custom similarity class for SOLR / Lucene using Eclipse
The class we used
package com.luxactive;
import org.apache.lucene.index.FieldInvertState;
import org.apache.lucene.search.similarities.DefaultSimilarity;
public class MyNewSimilarityClass extends DefaultSimilarity {
#Override
public float coord(int overlap, int maxOverlap) {
return 1.0f;
}
#Override
public float idf(long docFreq, long numDocs) {
return 1.0f;
}
#Override
public float lengthNorm(FieldInvertState arg0) {
return 1.0f;
}
#Override
public float tf(float freq) {
return 1.0f;
}
}
Create a simple jar with your Similarity
Copy the jar to any folder into your solr server, we used:
SOLRFOLDER/solr-4.8.0/example/solr/dih
The next steps need to be done to every collection you have!
Edit the solrconfig.xml at: SOLRFOLDER/solr-4.8.0/example/solr/collection/conf/solrconfig.xml
Add <lib dir="../dih" regex=".*\.jar" /> to import the custom jar
Edit the schema.xml in the same folder
Add the following
<!-- DEFAULT Factory for custom com.luxactive.MyNewSimilarityClass -->
<similarity class="solr.SchemaSimilarityFactory"/>
<!-- TYPE String -->
<fieldType name="no_term_frequency_string" class="solr.StrField" sortMissingLast="true" >
<similarity class="com.luxactive.MyNewSimilarityClass"/>
</fieldType>
<!-- TYPE Date -->
<fieldType name="no_term_frequency_date" class="solr.TrieDateField" sortMissingLast="true" >
<similarity class="com.luxactive.MyNewSimilarityClass"/>
</fieldType>
<!-- TYPE Int-->
<fieldType name="no_term_frequency_int" class="solr.TrieIntField" sortMissingLast="true" >
<similarity class="com.luxactive.MyNewSimilarityClass"/>
</fieldType>
Here you define your own field types (int, string and date) that use the new Similarity class which will return a boost value like defined in the MyNewSimilarityClass.
Now edit the fields you want to use your custom Similaritry by setting theyr type to one you created.
From: <field name="last_modified" type="date" indexed="true" stored="true" multiValued="false" />
To: <field name="last_modified" type="no_term_frequency_date" indexed="true" stored="true" multiValued="false" />
Restart the solr server and enjoy your boosting :)