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  1. Core Server
  2. SERVER-48557

Omit cursor.atClusterTime field from read replies in transactions

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    • Icon: Improvement Improvement
    • Resolution: Fixed
    • Icon: Major - P3 Major - P3
    • 4.7.0
    • None
    • Replication
    • None
    • Fully Compatible
    • Repl 2020-06-29

    Description

      In SERVER-47690, we added an "atClusterTime" field to cursor replies for non-transaction snapshot reads:

      > db.runCommand({find: "collection", readConcern: {level: "snapshot"}})
      // Server selects a read timestamp and replies with it
      {
        ok: 1,
        cursor: {
          firstBatch: [...],
          id: ...,
          atClusterTime: Timestamp(...)
        }
      }
      

      As a consequence of the implementation, cursor replies to snapshot reads that are in transactions also gained "atClusterTime", and we decided that was fine. Let's change our minds and omit the field for replies to commands in transactions. It's not useful.

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            lingzhi.deng@mongodb.com Lingzhi Deng
            jesse@mongodb.com A. Jesse Jiryu Davis
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              Updated:
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