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  1. WiredTiger
  2. WT-7527

Perform fine-tuning on reverse modifies for HS records

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    Details

    • Type: Improvement
    • Status: Open
    • Priority: Major - P3
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: 5.1 Required
    • Component/s: None
    • Labels:
      None
    • Story Points:
      8

      Description

      This ticket follows the work done in WT-7106. A new variable WT_MAX_CONSECUTIVE_REVERSE_MODIFY has been defined to limit the number of consecutive reverse modifies during reconciliation before performing a full update.

      Instead of having a hardcoded value, we could have a dynamic approach. Find below a few ideas from the WT-7106 discussion:

      • If a reverse delta uses 1% of the space a full record would, then we might store 100 reverse deltas per full update. If a reverse delta uses 50% or more of the space, we might store 10.
      • Store a reverse modify if it will save at least N bytes (or N% of the record size) where N increases with the number of consecutive reverse modifies we've stored.
      • This limit could also be based on per-table data instead of database wide.

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              Assignee:
              backlog-server-storage-engines Backlog - Storage Engines Team
              Reporter:
              etienne.petrel Etienne Petrel
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                Updated: