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  1. Core Server
  2. SERVER-49525

Sample documents to pick new split points for resharding when new shard key has a hashed field

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    • Fully Compatible
    • Sharding 2020-08-10

      Once the new $hash expression is created in SERVER-49214, we can use a similar agg pipeline as defined in SERVER-49510 to pick new split points during resharding for a shard key with a hashed field. The pipeline should use $hash for a hashed field, it should look like:

      [
    {
        $sample: { size: numInitialChunks * s (where s = oversampling ratio }
    },
    {
        $project: {
            _id: 0,
            "sk0": {$ifNull: ["$shardKeyField0", null]}, 
            "sk1": {$toHashedIndexKey: <input>},
            ... and so on for each shard key field
        }
    },
    {
        $sort: { sk0: 1, sk1: 1 }
    },
]

            Assignee:
            kshitij.gupta@mongodb.com Kshitij Gupta
            Reporter:
            janna.golden@mongodb.com Janna Golden
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              Created:
              Updated:
              Resolved: