I have an index of products, and these products have a "category" which we
can say for now is a good approximation of its location in the store. I'm
investigating altering the ordering of the results so that the categories
aren't interlaced as much... so that the results are a little bit more
grouped by category, but not *totally* grouped by category. It's
interesting because it's an approach that sort of compares results to
near-scored/ranked results. One of the hoped outcomes of this would that
there would be somewhat fewer categories represented in the top results for
a given query, although it is questionable if this is a good measurement to
determine the effectiveness of the implementation.
My first attempt was to
group=true&group.main=true&group.field=category&group.func=rint(scale(query({!type=edismax
v=$q}),0,20))
Or some FunctionQuery like that, so that in order to become a member of a
group, the doc would have to have the same category, and be dropped into
the same score bucket (20 in this case). This doesn't work out of the gate
due to an NPE (solr 4.10.2) (although I'm not sure it would work anyway):
java.lang.NullPointerException\n\tat
org.apache.lucene.queries.function.valuesource.ScaleFloatFunction.getValues(ScaleFloatFunction.java:104)\n\tat
org.apache.solr.search.DoubleParser$Function.getValues(ValueSourceParser.java:1111)\n\tat
org.apache.lucene.search.grouping.function.FunctionFirstPassGroupingCollector.setNextReader(FunctionFirstPassGroupingCollector.java:82)\n\tat
org.apache.lucene.search.MultiCollector.setNextReader(MultiCollector.java:113)\n\tat
org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:612)\n\tat
org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:297)\n\tat
org.apache.solr.search.Grouping.searchWithTimeLimiter(Grouping.java:451)\n\tat
org.apache.solr.search.Grouping.execute(Grouping.java:368)\n\tat
org.apache.solr.handler.component.QueryComponent.process(QueryComponent.java:459)\n\tat
org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:218)\n\tat
Has anyone tried something like this before, and does anyone have any novel
ideas for how to approach it, no matter how different? How about a
workaround for the group.func error here? I'm very open-minded about where
to go on this one.
Thanks,
Ryan
