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  1. Core Server
  2. SERVER-27510

Compare only epochs instead of full chunk versions in CollectionMetadata::checkChunkIsValid()

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    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Fixed
    • Affects Version/s: 3.4.1, 3.5.1
    • Fix Version/s: 3.4.2, 3.5.2
    • Component/s: Sharding
    • Labels:
      None
    • Backwards Compatibility:
      Fully Compatible
    • Backport Requested:
      v3.4
    • Sprint:
      Sharding 2017-01-02
    • Linked BF Score:
      0

      Description

      The check on the shard that the chunk's version sent by the config is the same as what the shard sees is a little counter productive: we bump the version of a random chunk on the donor with every migration, so a chunk that hasn't even moved away and back might get rejected for a moveChunk or splitChunk.

      Instead, we should just compare the chunk's epochs to protect against moving a chunk on a collection that was dropped and recreated.

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                • Created:
                  Updated:
                  Resolved: