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From Shawn Heisey <>
Subject Re: Group.ngroup query slower with docValues
Date Wed, 06 Nov 2013 16:38:46 GMT
On 11/6/2013 6:28 AM, vicky desai wrote:
> I am planning to use the docValues feature of Solr. I have added "docValues=
> true" parameter to a few fields in my schema on which there is heavy
> faceting and grouping query involved. While I noticed a considerable
> improvement in faceting queries. I didnt get any improvements in grouping
> query and instead places where i used "group.ngroups=true" in my query there
> was around 3-4 times degradation in performance.
> Any know issues or possible workarounds for this case

The group.ngroups=true feature has bad performance.  It's a fact that's
well known.  There is an issue to improve the situation, but mostly it's
just a feature request with no patch and no significant ideas.

There has been no activity on the issue since January, but the first
comment lists what may be a workaround that improves performance when
grouping on a single field.

I personally have never used the grouping feature and don't know if the
workaround is solid.  This is all the information I could find.


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