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From Mikhail Khludnev <mkhlud...@griddynamics.com>
Subject Re: [Solr 6] Migration from Solr 4.10.2
Date Tue, 24 May 2016 20:38:11 GMT
Alessandro,

I checked with Solr 6.0 distro on techproducts.
Faceting on cat with uif hits fieldValueCache
http://localhost:8983/solr/techproducts/select?facet.field=cat&facet.method=uif&facet=on&indent=on&q=*:*&wt=json

fieldValueCache
- class:org.apache.solr.search.FastLRUCache
- description:Concurrent LRU Cache(maxSize=10000, initialSize=10,
minSize=9000, acceptableSize=9500, cleanupThread=false)
- src:
- version:1.0 stats:

   - cumulative_evictions:0
   - cumulative_hitratio:0.5
   - cumulative_hits:1
   - cumulative_inserts:2
   - cumulative_lookups:2
   - evictions:0
   - hitratio:0.5
   - hits:1
   - inserts:2
   - item_cat:
   {field=cat,memSize=4665,tindexSize=46,time=28,phase1=27,nTerms=16,bigTerms=2,termInstances=21,uses=0}
   - lookups:2
   - size:1

Beware, for example field manu_exact doesn't hit field value cache, because
it single valued and goes to FacetFieldProcessorDV instead of
FacetFieldProcessorUIF.  And cat is multivalued and hits UIF. see
org.apache.solr.search.facet.FacetField.createFacetProcessor(FacetContext)
it might need to just debug there.

In summary, uif works and you have a chance to hit it. Goof Luck!

On Tue, May 24, 2016 at 7:43 PM, Alessandro Benedetti <
benedetti.alex85@gmail.com> wrote:

> Update , it seems clear I incurred in the bad
> https://issues.apache.org/jira/browse/SOLR-8096 :
>
> Just adding some additional information as I just incurred on the issue
> with Solr 6.0 :
> Static index, around 50 *10^6 docs, 20 fields to facet, 1 of them with high
> cardinality on top of grouping.
> Groping was not affecting at all.
>
> All the symptoms are there, Solr 4.10.2 around 150 ms and Solr 6.0 around
> 550 ms .
> The 'fieldValueCache' seems to be unused (no inserts nor lookups) in Solr
> 6.0.
> In Solr 4.10 the 'fieldValueCache' is in heavy use with a
> cumulative_hitratio of 0.96 .
> Switching from enum to fc to fcs to uif did not change that much.
>
> Moving to DocValues didn't improve that much the situation ( but I was on
> an optimized index, so I need to try the multi-segmented one according
> to Mikhail
> Khludnev
> <https://issues.apache.org/jira/secure/ViewProfile.jspa?name=mkhludnev>
> contribution
> in Solr 5.4.0 ) .
>
> Moving to field collapsing moved down the query to 110-120 ms ( but this is
> normal, we were faceting on 260 /1 million orignal docs)
> Adding facet.threads=NCores moved down the queryTime to 100 ms, in
> combination with field collapsing we reached 80-90 ms when warmed.
>
> What are the plan for the future related this ?
> Do we want to deprecate the legacy facets implementation and move
> everything to Json facets ( like it happened with the UIF ) ?
> So backward compatible but different implementation ?
>
> I think for migrations should be a transparent process.
>
>
> Cheers
>
> On Mon, May 23, 2016 at 6:49 PM, Alessandro Benedetti <
> benedetti.alex85@gmail.com> wrote:
>
> > Furthermore I was checking the internals of the old facet implementation
> (
> > which comes when using the classic request parameter based,  instead of
> the
> > json facet). It seems that if you enable docValues even with the enun
> > method passed as parameter , actually fc with docValues will be used.
> > i will give some report on the performance we get with docValues.
> >
> > Cheers
> > On 23 May 2016 16:29, "Joel Bernstein" <joelsolr@gmail.com> wrote:
> >
> >> If you can make min/max work for you instead of sort then it should be
> >> faster, but I haven't spent time comparing the performance.
> >>
> >> But if you're using the top_fc with the min/max param the performance
> >> between Solr 4 & Solr 6 should be very close as the data structures
> behind
> >> them are the same.
> >>
> >>
> >>
> >>
> >>
> >>
> >> Joel Bernstein
> >> http://joelsolr.blogspot.com/
> >>
> >> On Mon, May 23, 2016 at 3:34 PM, Alessandro Benedetti <
> >> abenedetti@apache.org
> >> > wrote:
> >>
> >> > Hi Joel,
> >> > thanks for the reply, actually we were not using field collapsing
> >> before,
> >> > we basically want to replace grouping with that.
> >> > The grouping performance between Solr 4 and 6 are basically
> comparable.
> >> > It's surprising I got so big degradation with the field collapsing.
> >> >
> >> > So basically the comparison we did were based on the Solr4 queries ,
> >> > extracted from logs, and modified slightly to include field collapsing
> >> > parameter.
> >> >
> >> > To build the tests to compare Solr 4.10.2 to Solr 6 we basically
> >> proceeded
> >> > in this way :
> >> >
> >> > 1) install Solr 4.10.2 and Solr 6.0.0
> >> > 2) migrate the index with the related lucene tool ( 4.10.2 -> 5.5.0
->
> >> Solr
> >> > 6.0 )
> >> > 3) switch on/off the 2 instances and repeating the tests both with
> cold
> >> > instances and warm instances.
> >> >
> >> > This means that the query looks the same.
> >> > I have not double checked the results but only the timings.
> >> > I will provide additional feedback to see if the query are producing
> >> > comparable results as well.
> >> >
> >> > Related your suggestion about the top_fc, thanks, I will try that .
> >> > I actually discovered that a little bit after I posted the mailing
> list
> >> ( I
> >> > think exactly from another post of yours :) )
> >> >
> >> > Not sure if setting up docValues for the field we use to collapse
> could
> >> > give some benefit as well.
> >> >
> >> > I keep you updated,
> >> >
> >> > Cheers
> >> >
> >> > On Mon, May 23, 2016 at 2:48 PM, Joel Bernstein <joelsolr@gmail.com>
> >> > wrote:
> >> >
> >> > > Were you using the sort param or min/max param in Solr 4 to select
> the
> >> > > group head? The sort work came later and I'm not sure how it
> compares
> >> in
> >> > > performance to the min/max param.
> >> > >
> >> > > Since you are collapsing on a string field you can use the top_fc
> hint
> >> > > which will use a top level field cache for the collapse. This is
> >> faster
> >> > at
> >> > > query time then the default which uses MultiDocValue ordinal map.
> >> > >
> >> > > The docs cover the top_fc hint.
> >> > >
> >> > >
> >> >
> >>
> https://cwiki.apache.org/confluence/display/solr/Collapse+and+Expand+Results
> >> > >
> >> > >
> >> > >
> >> > > Joel Bernstein
> >> > > http://joelsolr.blogspot.com/
> >> > >
> >> > > On Mon, May 23, 2016 at 12:14 PM, Alessandro Benedetti <
> >> > > abenedetti@apache.org> wrote:
> >> > >
> >> > > > 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
> >> > > >
> >> > >
> >> >
> >> >
> >> >
> >> > --
> >> > --------------------------
> >> >
> >> > 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
> Blog - http://alexbenedetti.blogspot.co.uk
>
> "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
>



-- 
Sincerely yours
Mikhail Khludnev
Principal Engineer,
Grid Dynamics

<http://www.griddynamics.com>
<mkhludnev@griddynamics.com>

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