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From "Hoss Man (JIRA)" <>
Subject [jira] [Commented] (SOLR-2524) Adding grouping to Solr 3x
Date Mon, 23 May 2011 06:06:47 GMT


Hoss Man commented on SOLR-2524:

bq. Solr trunk already has its own grouping implementation, from which we've factored out
a shared grouping module (see LUCENE-1421). That module is available in trunk and 3.x, but
since Solr already has grouping in trunk, and it has more features than the grouping module
(specifically, that you can group by docvalues derived from a function query and by arbitrary
query), Solr trunk will for now keep its own private impl.

FWIW: I'm a little wary of the idea that we might wind up with an alternate approach to the
"grouping" functionality released in 3.2 then what would then later be released in 4.0 ...
i haven't looked at the approach in branch enough to understand how they differ, but i'm concerned
about the hypothetical possibilities that they might have subtly differnet behavior in edge
cases, or different perf characteristics, or that 3.2 might add a feature that is hard to
support in 4.0, etc....

I say this only to raise it as a red flag to watch out for -- not because i want to stop the
progress on this issue.

The first question that sprang to mind when i saw this issue was: is backporting what solr
already uses on trunk to the 3x branch out of the question?

assuming it is, then i guess the main thing that would help ease my fears are if:

1) we had identical Solr tests (at the request api level) on trunk and 3x to help sanity check
that the two impls behave the same way
2) the folks working on the grouping refactoring felt confident that by the time we get arround
to releasing 4.0, the grouping refactoring would be at the point that the 3.2 impl and the
4.0 impl would be equivalent.

> Adding grouping to Solr 3x
> --------------------------
>                 Key: SOLR-2524
>                 URL:
>             Project: Solr
>          Issue Type: New Feature
>    Affects Versions: 3.2
>            Reporter: Martijn van Groningen
>            Assignee: Michael McCandless
>         Attachments: SOLR-2524.patch, SOLR-2524.patch, SOLR-2524.patch
> Grouping was recently added to Lucene 3x. See LUCENE-1421 for more information.
> I think it would be nice if we expose this functionality also to the Solr users that
are bound to a 3.x version.
> The grouping feature added to Lucene is currently a subset of the functionality that
Solr 4.0-trunk offers. Mainly it doesn't support grouping by function / query.
> The work involved getting the grouping contrib to work on Solr 3x is acceptable. I have
it more or less running here. It supports the response format and request parameters (expect:
group.query and group.func) described in the FieldCollapse page on the Solr wiki.
> I think it would be great if this is included in the Solr 3.2 release. Many people are
using grouping as patch now and this would help them a lot. Any thoughts?

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