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  1. WiredTiger
  2. WT-3768

Lookaside optimization: birthmarks

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    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 3.6.3, 3.7.1, WT3.1.0
    • Component/s: None
    • Labels:
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      Description

      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).

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              Assignee:
              keith.bostic Keith Bostic
              Reporter:
              michael.cahill Michael Cahill
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                Updated:
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