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Michael Gibney commented on SOLR-13257: --------------------------------------- [PR created|https://github.com/apache/lucene-solr/pull/677]. This ended up being a bit more involved than I'd anticipated, because I ended up integrating replica affinity with {{shards.preference}}. This seemed like the most natural place to add this functionality, and it will allow deterministic routing to be used in conjunction with other replica routing preferences (as a fallback/tie-breaker). There's also support for configuring default "base routing" preference in solrconfig.xml. > Enable replica routing affinity for better cache usage > ------------------------------------------------------ > > Key: SOLR-13257 > URL: https://issues.apache.org/jira/browse/SOLR-13257 > Project: Solr > Issue Type: Improvement > Security Level: Public(Default Security Level. Issues are Public) > Components: SolrCloud > Affects Versions: 7.4, master (9.0) > Reporter: Michael Gibney > Priority: Minor > Attachments: AffinityShardHandlerFactory.java > > > For each shard in a distributed request, Solr currently routes each request > randomly via > [ShufflingReplicaListTransformer|https://github.com/apache/lucene-solr/blob/master/solr/core/src/java/org/apache/solr/handler/component/ShufflingReplicaListTransformer.java] > to a particular replica. In setups with replication factor >1, this normally > results in a situation where subsequent requests (which one would hope/expect > to leverage cached results from previous related requests) end up getting > routed to a replica that hasn't seen any related requests. > The problem can be replicated by issuing a relatively expensive query (maybe > containing common terms?). The first request initializes the > {{queryResultCache}} on the consulted replicas. If replication factor >1 and > there are a sufficient number of shards, subsequent requests will likely be > routed to at least one replica that _hasn't_ seen the query before. The > replicas with uninitialized caches become a bottleneck, and from the client's > perspective, many subsequent requests appear not to benefit from caching at > all. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org