[SOLR-9094] ReRanker should gracefully handle sorts without score

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 4.10.4
• Component/s: search
• Labels: re-ranking

Environment

Solr 4.10.4
CentOS 6.5 64 bit
Java 1.8.0_51

• Assignee: Unassigned
• Reporter: Andrea Gazzarini
• Created: 09/May/16 19:35
• Updated: 05/Jul/19 15:22

Description

I have a Solr 4.10.4 instance with a RequestHandler that has a re-ranking query configured like this:

solrconfig.xml

<lst name="defaults">
            <str name="defType">dismax</str>
            ...
            <str name="rqq">{!boost b=someFunction() v=$q}</str>
            <str name="rq">{!rerank reRankQuery=$rqq reRankDocs=60 reRankWeight=1.2}</str>
            <str name="sort">score desc</str>
</lst>

Everything is working until the client sends a sort params that doesn't include the score field. So if for example the request contains "sort=price asc" then a NullPointerException is thrown:

09:46:08,548 ERROR [org.apache.solr.core.SolrCore] java.lang.NullPointerException
[INFO] [talledLocalContainer]     at org.apache.lucene.search.TopFieldCollector$OneComparatorScoringMaxScoreCollector.collect(TopFieldCollector.java:291)
[INFO] [talledLocalContainer]     at org.apache.solr.search.ReRankQParserPlugin$ReRankCollector.collect(ReRankQParserPlugin.java:263)
[INFO] [talledLocalContainer]     at org.apache.solr.search.SolrIndexSearcher.sortDocSet(SolrIndexSearcher.java:1999)
[INFO] [talledLocalContainer]     at org.apache.solr.search.SolrIndexSearcher.getDocListC(SolrIndexSearcher.java:1423)
[INFO] [talledLocalContainer]     at org.apache.solr.search.SolrIndexSearcher.search(SolrIndexSearcher.java:514)
[INFO] [talledLocalContainer]     at org.apache.solr.handler.component.QueryComponent.process(QueryComponent.java:484)
[INFO] [talledLocalContainer]     at org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:218)
[INFO] [talledLocalContainer]     at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:135)

The only way to avoid this exception is to explicitly add the "score desc" value to the incoming field; that is

?q=...&sort=price asc, score desc 

In this way I get no exception. I said "explicitly" because adding an "appends" section in my handler

<lst name="appends">
    <str name="sort">score desc</str>
</lst>

Even I don't know if that could solve my problem, in practice it is completely ignoring (i.e. I'm still getting the NPE above).

However, when I explicitly add "sort=price asc, score desc", as consequence of the re-ranking, the top 60 results, although I said to Solr "order by price", are still shuffled and that's not what I want.

So, at the end, the issue is about the following two points:

1. the NullPointerException above
2. a way to disable the re-ranking (automatically or not)

Issue Links

• is duplicated by: SOLR-9095 ReRanker should gracefully handle sorts without score