Keene Chen <kc...@mintel.com> wrote: > We have been doing some performance tests on Solr 5.5.2 > and Solr 8.5.2 as part of an upgrading process, and we have > noticed some reduced performance for certain types of > requests, particularly those that requests a large number of > rows, eg. 10000.
Solr 5→8… One large change is the switch to streaming docvalues in Solr 7, which has an effect on random access speed, especially if there are many documents per shard and only some of the documents has a value for the field. This should have been improved in Solr 8, so a factor 10 slowdown (median, 60 users) is surprising to me. Could you tell us how many fields you return for each document and how many of these are marked as Stored or/and DocValues? Also approximately how many documents you have per shard? And a sanity check: The default behaviour of document retrieval with regard to DocValues changed with schema version 1.6 (https://issues.apache.org/jira/browse/SOLR-8220). Have you checked that the same number of fields are returned for the two setups? - Toke Eskildsen?
