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From Alessandro Benedetti <abenede...@apache.org>
Subject Re: [Solr 6] Migration from Solr 4.10.2
Date Mon, 23 May 2016 11:14:40 GMT
Let's add some additional details guys :

1) *Faceting*
Currently the facet method used is "enum" and it runs over 20 fields more
or less.
Mainly using it on low cardinality fields except one which has a
cardinality of 1000 terms.
I am aware of the famous Jira related faceting regression :
https://issues.apache.org/jira/browse/SOLR-8096 .

Our index is indeed quite static ( we index once per day) and the fields we
facet on are multi-valued ( by schema definition but not in practise) .
But we use Term Enum as method so i was not expecting to hit the regression.
We currently see  query times which are 30% worse than Solr 4.10.2 .
Our next experiment will be to enable docValues for all the fields and
verify if we get any benefit ( switching the facet method to fc) .
At the moment, switching to json faceting is not an option as we would like
first to proceed with a transparent migration and then possibly add
improvements and refactor in the future.
Following will be to fix the schema to set as multi valued only what is
really multi-valued ( do you know if this can affect ? the wrong schema
definition is enough to mess up the facet performance ? even if then the
fields are single valued ?)


2) *Field Collapsing*
Field collapsing performance seems much, much worse, something like 200 ms
( Solr 4) vs 1800 ms ( Solr 6) .
This is suprising as I never heard about any regression in field collapsing.
I will investigate a little bit more in details about the internals of the
field collapsing and why the performance could be so degraded.
I will also verify if I find any info in the mailing list or Jira.

&fq={!collapse field=string_field sort='TrieDoubleField asc'}

let me know if you faced something similar

Cheers

On Fri, May 13, 2016 at 10:41 PM, Alessandro Benedetti <
abenedetti@apache.org> wrote:

> I'm planning a migration from 4.10.2 to 6.0 .
> Because we generate the index on daily basis from scratch, we don't need
> to migrate the index but actually only migrate the server instances.
> With my team we were doing some experiments on some dev machines,
> basically comparing Solr 4.10.2 and Solr 6.0 to check any functional and
> performance regression in our use cases.
>
> After setting up two installation on the same machine ( switching on and
> off each version for doing comparison and experiments) we are verifying a
> degradation of the performances with Solr 6.
>
> Basically from a queryTime and throughput perspective Solr 6 is not
> performing as well as Solr 4.10.2 .
> Still need to start the proper investigations but this appears weird to me.
> Will proceed with all the analysis of the case and a deep study of our
> queries ( which anyway are mainly fq , faceting and grouping).
>
> Any suggestion in particular to start with ? Has anyone experienced a
> similar migration with similar experience ?
> I will anyway explore also the mailing list in search for similar cases.
>
> Cheers
>
> --
> --------------------------
>
> Benedetti Alessandro
> Visiting card : http://about.me/alessandro_benedetti
>
> "Tyger, tyger burning bright
> In the forests of the night,
> What immortal hand or eye
> Could frame thy fearful symmetry?"
>
> William Blake - Songs of Experience -1794 England
>



-- 
--------------------------

Benedetti Alessandro
Visiting card : http://about.me/alessandro_benedetti

"Tyger, tyger burning bright
In the forests of the night,
What immortal hand or eye
Could frame thy fearful symmetry?"

William Blake - Songs of Experience -1794 England

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