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  1. Drivers
  2. DRIVERS-1729

Investigate changes in PM-1970: Change the Default Read Concern to Always Be Local

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    • Icon: Epic Epic
    • Resolution: Won't Do
    • Icon: Major - P3 Major - P3
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    Description

      Downstream Change Summary

      The current read concern default for sharded secondary reads (that are not associated with a causally consistent session) is 'available' and in all other cases is 'local'. Starting in 5.0, we plan to change the default read concern to always be 'local'.

      Description of Linked Ticket

      Epic Summary

      Summary

      Review the current read and write concern settings and propose changes to provide more intuitive and safe defaults.

      Motivation

      There are two primary motivations for adjusting our defaults. First, although MongoDB allows users to choose the right tradeoff between performance and consistency, the nuances of the system are complex and are often misused, or surprising to users. We should provide more intuitive and stronger consistency default settings out of the box. Second, MongoDB has battled with the user perception that it is not reliable or intentionally chooses unsafe defaults to appear faster in benchmarks. By changing the defaults, we eliminate that argument.

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      Scope Document
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            Unassigned Unassigned
            backlog-server-pm Backlog - Core Eng Program Management Team
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