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From Joel Bernstein <>
Subject Re: Does DocValues improve Grouping performance ?
Date Fri, 30 Jan 2015 23:41:32 GMT
A few questions so we can better understand the scale of grouping you're
trying to accomplish:

How many distinct groups do you typically have in a search result?

How many distinct groups are there in the field you are grouping on?

How many results are you trying to group in a query?

Joel Bernstein
Search Engineer at Heliosearch

On Fri, Jan 30, 2015 at 4:10 PM, Cario, Elaine <> wrote:

> Hi Shamik,
> We use DocValues for grouping, and although I have nothing to compare it
> to (we started with DocValues), we are also seeing similar poor results as
> you: easily 60% overhead compared to non-group queries.  Looking around for
> some solution, no quick fix is presenting itself unfortunately.
> CollapsingQParserPlugin also is too limited for our needs.
> -----Original Message-----
> From: Shamik Bandopadhyay []
> Sent: Thursday, January 15, 2015 6:02 PM
> To:
> Subject: Does DocValues improve Grouping performance ?
> Hi,
>    Does use of DocValues provide any performance improvement for Grouping ?
> I' looked into the blog which mentions improving Grouping performance
> through DocValues.
> Right now, Group by queries (which I can't sadly avoid) has become a huge
> bottleneck. It has an overhead of 60-70% compared to the same query san
> group by. Unfortunately, I'm not able to be CollapsingQParserPlugin as it
> doesn't have a support similar to "group.facet" feature.
> My understanding on DocValues is that it's intended for faceting and
> sorting. Just wondering if anyone have tried DocValues for Grouping and saw
> any improvements ?
> -Thanks,
> Shamik

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