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  1. Core Server
  2. SERVER-56520

Time-series inserts spent a lot of time in wt_calc_modify but don't generate deltas

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    • Type: Icon: Bug Bug
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 5.0.0-rc2, 5.1.0-rc0
    • Affects Version/s: None
    • Component/s: None
    • None
    • Fully Compatible
    • ALL
    • v5.0
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      Run TSBS with cpu-only workload. Run db.point_data.stats() and look at the number of cursor modify operations. It doesn't increase during the work load, but attaching a profiles shows significant time spent in wiredtiger_calc_modify.

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      Run TSBS with cpu-only workload. Run db.point_data.stats() and look at the number of cursor modify operations. It doesn't increase during the work load, but attaching a profiles shows significant time spent in wiredtiger_calc_modify .
    • Execution Team 2021-05-31, Execution Team 2021-06-14

      We spend 25% of time on attempting to compute WT_MODIFY deltas, but never succeed to the limit of 16 changes. We should either support deltas with more than 16 changes, or find a way to avoid useless calculations.

      Probably it is best to directly change the doc_diff updates into deltas.

            Assignee:
            yuhong.zhang@mongodb.com Yuhong Zhang
            Reporter:
            geert.bosch@mongodb.com Geert Bosch
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              Created:
              Updated:
              Resolved: