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  1. Core Server
  2. SERVER-35999

A $changeStream can trigger assertion on UUID check when the collection cache is stale

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Duplicate
    • Affects Version/s: 3.6.5
    • Fix Version/s: None
    • Component/s: Aggregation Framework
    • Labels:
      None
    • Operating System:
      ALL
    • Sprint:
      Query 2018-07-30

      Description

      UUIDs were introduced in v3.6, however after upgrading from 3.4 it's possible that the collection state in-memory cache contains an entry for the collection (meaning it's sharded) but does not contain a UUID.  As such, this assertion will fail when a $changeStream compares the UUID from the oplog entry to the UUID in the collection state cache.

       Edit:

      Since change streams requires readConcern majority, the secondary will perform a shard version check but not necessarily refresh its cache. For change streams, mongos will not attach a shard version which means that the version check will always pass and no refresh is performed.

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              Assignee:
              nicholas.zolnierz Nicholas Zolnierz
              Reporter:
              nicholas.zolnierz Nicholas Zolnierz
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