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  1. Core Server
  2. SERVER-18022

Support "read committed" isolation level where "committed" means confirmed by the voting majority of a replica set

    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 3.1.7
    • Component/s: Querying, Replication
    • Labels:
      None
    • Backwards Compatibility:
      Fully Compatible
    • Epic Link:
    • Sprint:
      Quint Iteration 3, Quint Iteration 4, Quint Iteration 5, Quint Iteration 6, Quint Iteration 7, QuInt 8 08/28/15

      Description

      Writes in MongoDB replica sets are "committed" when the majority of voting nodes in the replica set confirm the write (n.b., arbiters cannot confirm writes). This ticket is to add a feature to query-like operations (find, count, aggregate, etc) to restrict the data observed to data known to have been committed at the replica set level. It is an approximate but imperfect analog of "w: majority" writes.

      In MongoDB deployments using an MVCC storage engine, such as WiredTiger, this behavior could be implemented by having the replication subsystem retain the newest "known committed" version of data on each node, and have the query system serve "committed" reads from that version rather than the newest version.

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                  Updated:
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