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From Kempelen, Ákos <>
Subject RE: Result grouping performance
Date Thu, 23 Nov 2017 12:53:00 GMT
Hi Mikhail,

group.facet=false, but group.truncate=true.
I found out that if the group.truncate parameter is true, the query will be much slower (x5
times), regardless of faceting.
I thought, that the group.truncate param is meaningless without activating the facet system,
but this is not the case.

Testing environment: Solr 7.0.1, 1 core with 70GB data (~1.000.000 documents), no shards


-----Original Message-----
From: Mikhail Khludnev [] 
Sent: Thursday, November 23, 2017 8:38 AM
To: solr-user <>
Subject: Re: Result grouping performance

Can you provide your request params? Do you just group and/or count grouped facets?
Can you clarify how field collapsing is different from grouping, just make it unambiguous?

On Wed, Nov 22, 2017 at 4:13 PM, Kempelen, Ákos <>

> Hello,
> I am migrating our codebase from Solr 4.7 to 7.0.1 but the performance 
> of result grouping seems very poor using the newer Solr.
> For example a simple MatchAllDocsQuery takes 5 sec on Solr4.7, and 21 
> sec on Solr7.
> I wonder what causes the x4 difference in time? We hoped that newer 
> Solr versions will provide better performances...
> Using Field collapsing could would be a solution, but it produces 
> different facet counts.
> Thanks,
> Akos

Sincerely yours
Mikhail Khludnev
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