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  1. Core Server
  2. SERVER-49890

Create local.system.resharding.slimOplogForGraphLookup view on donor shards

    • Fully Compatible
    • Sharding 2020-09-07

      Original description:
      This view should be created before the donor shard has chosen its fetchTimestamp.

      This local.system.resharding.slimOplogForGraphLookup view is created on startup of any 4.6 binary code that ensures the oplog exists (presumably, any launch using --replSets). The view is never deleted and considered harmless on earlier versions. Moreover the view won't initial sync due to being in local.
      It's definition:

      {
          _id: "local.system.resharding.slimOplogForGraphLookup",
          viewOn: "oplog.rs",
          pipeline: [
              {$project: {
                  op: 1,
                  o: {applyOps: {ui: 1, reshardDest: 1}},
                  ts: 1,
                  // The next expression masks out the prevOpTime for any retryable write. This only preserves 
                  // prevOpTime backpointers for multi-document transactions.
                  "prevOpTime.ts": {$cond: {
                      if: {$eq: [{$type: "$stmtId"}, "missing"]},
                      then: "$prevOpTime.ts",
                      else: Timestamp(0, 0),
                  }}},
              }},
          ],
      }
      

            Assignee:
            daniel.gottlieb@mongodb.com Daniel Gottlieb (Inactive)
            Reporter:
            max.hirschhorn@mongodb.com Max Hirschhorn
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              Created:
              Updated:
              Resolved: