Using sort_values (fsv=true parameter) and Field Collapsing (group=true) at the same time

[Jose Aguilar <JA...@searchtechnologies.com>]

Hi all,

I am using Solr 4.0 trunk with the Field Collapsing feature (http://wiki.apache.org/solr/FieldCollapsing) and I notice that when used at the same time as the fsv=true parameter, the sort_values in the response is gone. I haven't found much information about the fsv parameter, so I turned to the list to see if someone here can help us out, or shed some light if there is any incompatibility between the two features (which is what I think is happening, because of the field collapse implementation). Or maybe give us some pointers on how to achieve a similar effect.

We use fsv=true to help in debugging as to why one document was sorted on top of the other when using certain sort orders in our application, so this is a  great way to visualize this and save us debugging time.

To clarify further, we send in this query to Solr expecting the <grouped>, <sort_values> and <debug> tags to be on the response, with the <sort_values> arrays corresponding to the first element of each group:

http://localhost:8983/solr/select?wt=xml&fl=*&q=solr+memory&group=true&group.field=manu_exact&fsv=true&debugQuery=on…

But we don't get the <sort_values> part back, we only get the following top-level tags in the response:
<response>
<lst name="responseHeader">…
<lst name="grouped">…
<lst name="debug">…
</response>

If we don't use Field Collapsing, and instead send in something like this:

http://localhost:8983/solr/select?wt=xml&fl=*&q=solr+memory&fsv=true&debugQuery=on…

Then we do get the <sort_values> element in the response:

<response>
<lst name="responseHeader">
<lst name="sort_values">
<result name="response"…
<lst name="debug">
</response>

Is there some incompatibility between the two features? Any other way to retrieve this information in a way that would be compatible with field collapsing?

Thanks,

Jose Aguilar