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  1. WiredTiger
  2. WT-3768

Lookaside optimization: birthmarks

    • Type: Icon: Improvement Improvement
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 3.6.3, 3.7.1, WT3.1.0
    • Affects Version/s: None
    • Component/s: None
    • None
    • Storage 2017-12-04, Storage 2017-12-18
    • v3.6

      If we had "birthmarks", an inverse of tombstones (WT_UPDATE with type WT_UPDATE_DELETED), with the following sematics:

      • if a birthmark is not visible, it is equivalent to a tombstone; and
      • if a birthmark is visible, the on-page value is returned.

      Then when saving updates for lookaside eviction or update / restore, we could create a birthmark in the saved update list instead of making a full copy of the on-page value. For many common cases, this could dramatically reduce the amount of data that has to be written to the lookaside table (or stored in cache).

            Assignee:
            keith.bostic@mongodb.com Keith Bostic (Inactive)
            Reporter:
            michael.cahill@mongodb.com Michael Cahill (Inactive)
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              Created:
              Updated:
              Resolved: