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 < abenede...@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 < > abenede...@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 >
