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

XMLWordPrintableJSON

    • Fully Compatible
    • Sharding 2020-08-10
    • None
    • None
    • None
    • None
    • None
    • None
    • None

      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 (Inactive)
            Reporter:
            Janna Golden
            Votes:
            0 Vote for this issue
            Watchers:
            3 Start watching this issue

              Created:
              Updated:
              Resolved: