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From Martijn v Groningen <martijn.v.gronin...@gmail.com>
Subject Re: Issue with field collapsing in solr 4 while performing distributed search
Date Mon, 11 Jun 2012 12:53:42 GMT
The ngroups returns the number of groups that have matched with the
query. However if you want ngroups to be correct in a distributed
environment you need
to put document belonging to the same group into the same shard.
Groups can't cross shard boundaries. I guess you need to do
some manual document partitioning.

Martijn

On 11 June 2012 14:29, Nitesh Nandy <niteshnandy@gmail.com> wrote:
> Version: Solr 4.0 (svn build 30th may, 2012) with Solr Cloud  (2 slices and
> 2 shards)
>
> The setup was done as per the wiki: http://wiki.apache.org/solr/SolrCloud
>
> We are doing distributed search. While querying, we use field collapsing
> with "ngroups" set as true as we need the number of search results.
>
> However, there is a difference in the number of "result list" returned and
> the "ngroups" value returned.
>
> Ex:
> http://localhost:8983/solr/select?q=message:blah%20AND%20userid:3&&group=true&group.field=id&group.ngroups=true
>
>
> The response XMl looks like
>
> <response>
> <script/>
> <lst name="responseHeader">
> <int name="status">0</int>
> <int name="QTime">46</int>
> <lst name="params">
> <str name="group.field">id</str>
> <str name="group.ngroups">true</str>
> <str name="group">true</str>
> <str name="q">messagebody:monit AND usergroupid:3</str>
> </lst>
> </lst>
> <lst name="grouped">
> <lst name="id">
> <int name="matches">10</int>
> <int name="ngroups">9</int>
> <arr name="groups">
> <lst>
> <str name="groupValue">320043</str>
> <result name="doclist" numFound="1" start="0">
> <doc>...</doc>
> </result>
> </lst>
> <lst>
> <str name="groupValue">398807</str>
> <result name="doclist" numFound="5" start="0" maxScore="2.4154348">...
> </result>
> </lst>
> <lst>
> <str name="groupValue">346878</str>
> <result name="doclist" numFound="2" start="0">...</result>
> </lst>
> <lst>
> <str name="groupValue">346880</str>
> <result name="doclist" numFound="2" start="0">...</result>
> </lst>
> </arr>
> </lst>
> </lst>
> </response>
>
> So you can see that the ngroups value returned is 9 and the actual number
> of groups returned is 4
>
> Why do we have this discrepancy in the ngroups, matches and actual number
> of groups. Is this an open issue ?
>
>  Any kind of help is appreciated.
>
> --
> Regards,
>
> Nitesh Nandy



-- 
Met vriendelijke groet,

Martijn van Groningen

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