Thanks for your answer Erick. Just to clarify something, we are not returning 1000 docs per request, we are only returning 100. We get 10 requests to Solr querying for docs 1 to 100, then 101 to 200, ... until 901 to 1000. But all that in the exact same second.
But I understand that to retrieve docs 901 to 1000, Solr needs to first get and sort the first 900 docs, so the request to get 901 to 1000 is as costly as asking for 1 to 1000 directly? If the sort applies on an indexed field (isn't it mandatory?), why do Solr needs to read the first 900 docs ? Regards, Gaël ________________________________ De : Erick Erickson <erickerick...@gmail.com> Envoyé : lundi 13 janvier 2020 14:44 À : solr-user@lucene.apache.org <solr-user@lucene.apache.org> Objet : Re: Querying multiple pages for same keyword at same time To return stored values, Lucene must 1> read the stored values from disk 2> decompress a minimum 16K block 3> assemble the return packet. So you’re returning 500-1,000 documents per request, it may just be the above set of steps. Solr was never designed to _return_ large result sets. Search them, yes but not return. So if this never happens when you only return a few docs, this is probably your problem. There are two ways of making this less work for Solr, both depend on returning only docValues="true” fields. 1> return only docValues fields. See useDocValuesAsStored. 2> use the /export handler. Best, Erick > On Jan 13, 2020, at 5:31 AM, Gael Jourdan-Weil > <gael.jourdan-w...@kelkoogroup.com> wrote: > > Hello, > > We are experiencing some performance issues on Solr that seems related to > requests querying multiple pages of results for the same keyword at the same > time. > For instance, querying 10 pages of results (with 50 or 100 results per page) > in the same second for a given keyword, and doing that on different keywords > at the same time also. > > The performance issues we observe is a high CPU usage and response time > increasing a lot. > > This doesn't seem related to the number of requests itself because we can > handle a lot more requets per second when there is no such requests. > > Do you think this makes sense and can be explained by the way Solr works? > > Environment: SolrCloud 7.6.0 > > Gaël
