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From Martijn v Groningen <>
Subject Re: Stats per group with StatsComponent?
Date Wed, 30 Nov 2011 13:58:04 GMT
Hi Morten,

I missed your question on the user mailing list. Here is my answer:

With the StatsComponent this isn't possible at the moment. The
StatsComponent will give you the min / max of field for the whole
query result.
If you want the min / max value per group you'll need to do some
coding. The grouping logic is executed inside Lucene collectors
located in the
grouping module. You'll need to create a new second pass collector
that computes the min / max for the top N groups. This collector then
needs to
be wired up in Solr. The AbstractSecondPassGroupingCollector is
something you can take a look at. It collects the top documents for
the top N groups.

You don't need to have a patch to open an issue. Just open an issue
with a good description and maybe some implementation details.


On 30 November 2011 14:25, Morten Lied Johansen <> wrote:
> Hi
> I posted the below mail to the solr-user list a little over a week ago.
> Since there has been no response, we assume this means that what we need is
> not currently possible.
> We need this functionality, and are willing to put in time and effort to
> implement it, but could use some pointers to where it would be natural to
> add this, and ideas for how to best solve it.
> I'm also wondering if I should create an issue in JIRA right away, or if I
> should wait until we have a first patch ready?
> -------- Original Message --------
> Subject: Stats per group with StatsComponent?
> Date: Tue, 22 Nov 2011 14:40:45 +0100
> From: Morten Lied Johansen <>
> Reply-To:
> To:
> Hi
> We need to get minimum and maximum values for a field, within a group in
> a grouped search-result. Is this possible today, perhaps by using
> StatsComponent some way?
> I'll flesh out the example a little, to make the question clearer.
> We have a number of documents, indexed with a price, date and a hotel.
> For each hotel, there are a number of documents, each representing a
> price/date combination. We then group our search result on hotel.
> We want to show the minimum and maximum price for each hotel.
> A little googling leads us to look at StatsComponent, as what it does
> would be what we need, if it could be done for each group. There was a
> thread on this list in August, "Grouping and performing statistics per
> group" that seemed to go into this a bit, but didn't find a solution.
> Is this possible in Solr 3.4, either with StatsComponent, or some other way?
> --
> Morten
> We all live in a yellow subroutine.
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Met vriendelijke groet,

Martijn van Groningen

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