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  1. Solr
  2. SOLR-13257

Enable replica routing affinity for better cache usage

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Details

    • New Feature
    • Status: Closed
    • Minor
    • Resolution: Fixed
    • None
    • 8.3, 9.0
    • SolrCloud
    • None

    Description

      For each shard in a distributed request, Solr currently routes each request randomly via ShufflingReplicaListTransformer 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.

      Attachments

        1. AffinityShardHandlerFactory.java
          5 kB
          Michael Gibney
        2. SOLR-13257.patch
          35 kB
          Michael Gibney
        3. SOLR-13257.patch
          35 kB
          Jan Høydahl

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              anshum Anshum Gupta
              magibney Michael Gibney
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                Resolved:

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