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  1. Cassandra
  2. CASSANDRA-15836

nodetool garbagecollect could leave LCS level intact

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    Details

    • Type: Improvement
    • Status: Triage Needed
    • Priority: Normal
    • Resolution: Unresolved
    • Fix Version/s: None
    • Component/s: Local/Compaction
    • Labels:
      None
    • Platform:
      All
    • Impacts:
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      Description

      The nodetool command `garbagecollect` will run a single-sstable compaction for every sstable in a cf, while using other sstables on the side to allow for dropping tombstoned data. However, in doing so, it resets all LCS levels back to 0, causing a significant write amplification.

      Fundamentally there's no reason why LCS levels have to be changed here, since these are single-sstable compactions. When the expected reduction in data set size is small (say, 10%) it may be preferable for sstables to remain in place instead of having to go through the entire compaction process again.

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            • Assignee:
              Unassigned
              Reporter:
              tvdw Tom van der Woerdt
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              Dates

              • Created:
                Updated: