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  1. Core Server
  2. SERVER-47812

Secondaries persist wildcard multikeypaths out of order

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    • Fully Compatible
    • ALL
    • v4.4, v4.2
    • Query 2020-08-24, Query 2020-09-07, Query 2020-09-21
    • 33

    Description

      Because secondaries apply operations out of order, the following scenario can play out in the absence of special logic:

      {op: "i", o: {_id: "A", a: [1,2]}, ts: Timestamp(1, 1)}}
      {op: "i", o: {_id: "B", a: [1,2]}, ts: Timestamp(1, 2)}}
       
      | Applier 1            | Applier 2                    | Reader                                    |
      |----------------------+------------------------------+-------------------------------------------|
      | Begin Txn            |                              |                                           |
      | Write B              |                              |                                           |
      | Update Indexes       |                              |                                           |
      | Update Multikeypaths |                              |                                           |
      | TimestampTxn (1, 2)  |                              |                                           |
      | Commit               |                              |                                           |
      |                      | Begin Txn                    |                                           |
      |                      | Write A                      |                                           |
      |                      | Update Indexes               |                                           |
      |                      | (No Multikeypaths to update) |                                           |
      |                      | TimestampTxn (1, 1)          |                                           |
      |                      | Commit                       |                                           |
      |                      |                              | BeginTxn                                  |
      |                      |                              | ReadTimestamp (1,1)                       |
      |                      |                              | Sees A                                    |
      |                      |                              | Does not see corresponding multikey paths |
      

      See this comment for persisting classical index multikey paths.

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              bernard.gorman@mongodb.com Bernard Gorman
              daniel.gottlieb@mongodb.com Daniel Gottlieb
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