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  1. Documentation
  2. DOCS-13395

Investigate changes in SERVER-43069: Ops that are slow to apply don't condition on slowOpSampleRate


      Downstream Change Summary

      Conditioned logging for slow operations on the sample rate.

      Existing behavior prior to this ticket: https://docs.mongodb.com/manual/release-notes/4.2/#slow-oplog

      Description of Linked Ticket

      Here's the code in question: https://github.com/mongodb/mongo/blob/r3.6.14/src/mongo/db/repl/sync_tail.cpp#L335-L351

      That should be doing something similar to https://github.com/mongodb/mongo/blob/r3.6.14/src/mongo/db/ops/write_ops_exec.cpp#L122-L124

      This behaviour is called out in https://docs.mongodb.com/manual/release-notes/4.2/#slow-oplog, though I don't see any discussion on SERVER-32146 or DOCS-12178 for whether sampling was considered.

      There's also a couple other places where this might need to be checked:

      It's possible a better fix would be to decouple slowOpSampleRate and slowms, such that you log all slow operations but then subject non-slow ops to sampling.

      Scope of changes

      Impact to Other Docs

      MVP (Work and Date)

      Resources (Scope or Design Docs, Invision, etc.)

            jeffrey.allen@mongodb.com Jeffrey Allen
            backlog-server-pm Backlog - Core Eng Program Management Team
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              2 years, 28 weeks ago