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  1. Documentation
  2. DOCS-11247

Docs for SERVER-28923: Add diagnosability and supportability features for retryable writes

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    Description

      Documentation Request Summary:

      This ticket added a new section to the serverStatus response called "transactions" that contains 3 new fields:

      • "retriedCommandsCount"
        • The total number of received write commands with statements that have already been executed, across all sessions
      • "retriedStatementsCount"
        • The total number of received statements that have already been executed, across all sessions
      • "transactionsCollectionWriteCount"
        • The total number of writes to the config.transactions collection, triggered when a new retryable write statement is committed. For updates and deletes there is one write per statement, but there is only one per batch of documents inserted, except when there is a failure that leads to each document being inserted separately.

      "retriedCommandsCount" and "retriedStatementsCount" both ignore any retryable writes that may happen internally as part of a chunk migration, but "transactionsCollectionWriteCount" does include writes to a server's config.transactions collection that occur as part of a migration.

      All three are NumberLongs.

      Scope of changes:

      • serverStatus (backport to 3.6)
      • retryable writes (backport to 3.6)

      Impact to other docs outside of this product:

      none

      MVP:

      Resources:

      Engineering Ticket Description:

      This ticket is a placeholder to figure out between ourselves and with TSE what supportability and diagnosability enhancements we might need to include for retryable writes.

      Things that come to mind include:

      • FTDC metrics for number of active sessions
      • Metrics for the CPU (and if possible I/O) overhead of maintaining the retryability metadata
      • Metrics for number of writes which have been retried
      • If we end up with a cache, metrics for hit-rate

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            kay.kim@mongodb.com Kay Kim (Inactive)
            kay.kim@mongodb.com Kay Kim (Inactive)
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            Dates

              Created:
              Updated:
              Resolved:
              5 years, 35 weeks, 1 day ago