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  1. Core Server
  2. SERVER-39234

Sharding an empty collection in mixed-shard version configurations may leave all chunks on the primary shard

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Details

    • Bug
    • Status: Closed
    • Major - P3
    • Resolution: Fixed
    • 4.0.5
    • 4.0.6, 4.1.8
    • Sharding
    • None
    • Fully Compatible
    • ALL
    • v4.0
    • Sharding 2019-02-11
    • 50

    Description

      In partially upgraded clusters, whose config server is at version 4.0.5 and shards are at pre-4.0.3 (includes 3.6), sharding an empty collection with hashed sharding or performing map/reduce with outputting to an empty collection (with any kind of sharding) will end up placing all chunks on the primary shard of the collection.

      This is not a correctness issue, but it means that the balancer will have to move non-empty chunks later on and thus defeats the purpose of pre-sharding the collection.

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            kaloian.manassiev@mongodb.com Kaloian Manassiev
            kaloian.manassiev@mongodb.com Kaloian Manassiev
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              Created:
              Updated:
              Resolved: