Also I wrote a guide for Solr 5 Collapsing/Expand performance, that use to be on Heliosearch.org. It's now long available accept through the magic of the Wayback machine. What's not covered is the sort param, which came later.
Here it is: http://web.archive.org/web/20150709154420/http://heliosearch.org/solr5-collapse-expand Joel Bernstein http://joelsolr.blogspot.com/ On Mon, May 23, 2016 at 2:48 PM, Joel Bernstein <joels...@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 < > 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 >> > >
