Hi, I've recently upgraded to SolrCloud (4.4) from Master-Slave mode. One of the changes I did the in queries is to add group functionality to remove duplicate results. The grouping is done on a specific field. But the change seemed to have a huge effect on the query performance. The "group" option decreased the performance by 10 times. For e.g. this query takes 1 sec to execute. The number of results is around 105387.
http://localhost:8083/solr/browse?fq=language:(english)&wt=xml&rows=10&start=0&fq=(ContentGroup-local:"Learn & Explore" OR ADSKContentGroup-local:"Getting Started")&q=line&sort=score desc&group=true&group.field=dedup&group.ngroups=true If I exclude group option, it comes down to 190ms http://localhost:8083/solr/browse?fq=language:(english)&wt=xml&rows=10&start=0&fq=(ContentGroup-local:"Learn & Explore" OR ADSKContentGroup-local:"Getting Started")&q=line I'm running this query against a 8 million doc index . I've 2 shard with 1 replica each, running on a m1x.large EC2 instance, each having 8gb allocat ed memory. Is this a known issue or am I missing something which is making this query expensive. I bumped into this JIRA --> https://issues.apache.org/jira/browse/SOLR-5027 which talks about CollapsingQParserPlugin as an alternate to grouping, but that seemed to be available in 4.6. Just wondering if it can be an alternate in my case and whether if its possible to apply as a patch in 4.4 version. Any pointer will be appreciated. - Thanks, Shamik
