On 3/23/2018 3:47 PM, Webster Homer wrote: > Just FYI I had a project recently where I tried to use cursorMark in > Solrcloud and solr 7.2.0 and it was very unreliable. It couldn't even > return consistent numberFound values. I posted about it in this forum. > Using the start and rows arguments in SolrQuery did work reliably so I > abandoned cursorMark as just too buggy > > I had originally wanted to try using streaming expressions, but they don't > return results ordered by relevancy, a major limitation for a search > engine, in my opinion.
The problems that can affect cursorMark are also problems when using start/rows pagination. You've mentioned relevancy ordering, so I think this is what you're running into: Trying to use relevancy ranking on SolrCloud with NRT replicas can break pagination. The problem happens both with cursorMark and start/rows. NRT replicas in a SolrCloud index can have different numbers of deleted documents. Even though deleted documents do not appear in search results, they ARE still part of the index, and can affect scoring. Since SolrCloud load balances requests across replicas, page 1 may use different replicas than page 2, and end up with different scoring, which can affect the order of results and change which page number they end up on. Using TLOG or PULL replicas (available since 7.0) usually fixes that problem, because different replicas are 100% identical with those replica types. Changing the index in the middle of trying to page through results can also cause issues with pagination. Thanks, Shawn
