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  1. MongoDB Database Tools
  2. TOOLS-3406

Investigate changes in PM-1941: Improved change stream shard-targeting and handling of cluster topology changes

    • Type: Icon: Investigation Investigation
    • Resolution: Unresolved
    • Priority: Icon: Major - P3 Major - P3
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    • Affects Version/s: None
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    • 205

      Original Downstream Change Summary

      New parameters added to $changeStream aggregation stage.

      Description of Linked Ticket

      Epic Summary


      Change streams on sharded clusters should return correct events when shards are removed or added.


      This has been a user request and will allow us to offer change streams for more use cases while increasing client-side debugability. There are scenarios that may lead to incorrect events for change stream users on sharded clusters. 

      For example: if a shard gets removed from a cluster before we are finished reading events from it and we resume a stream from a point before the shard was removed, we will silently skip every event that occurred on the removed shard between that time and the point where it was removed. This violates one of change streams’ fundamental guarantees (no skipped events).

      In a serverless world, where we want to be able to add and remove shards at will, this will become an important issue to fix. 

      Cast of Characters

      • Product Owner: Katya Kamenieva
      • Project Lead: Mindaugas Malinauskas
      • Program Manager: Ana Meza
      • Drivers Contact: TBD


      Scope Document
      Technical Design Document
      Product Description
      Docs Update

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            backlog-server-pm Backlog - Core Eng Program Management Team
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