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  1. Cassandra
  2. CASSANDRA-8635

STCS cold sstable omission does not handle overwrites without reads

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Urgent
    • Resolution: Fixed
    • Fix Version/s: 2.1.3
    • Component/s: Local/Compaction
    • Labels:
      None
    • Severity:
      Critical

      Description

      In 2.1, STCS may omit cold SSTables from compaction (CASSANDRA-6109). If data is regularly overwritten or deleted (but not enough to trigger a single-sstable tombstone purging compaction), data size on disk may continuously grow if:

      • The table receives very few reads
      • The reads only touch the newest SSTables

      Basically, if the overwritten data is never read and there aren't many tombstones, STCS has no incentive to compact the sstables. We should take sstable overlap into consideration as well as coldness to address this case.

        Attachments

        1. 8635-v2.patch
          16 kB
          Marcus Eriksson
        2. 0001-Include-cold-sstables-in-compactions-if-they-overlap.patch
          12 kB
          Marcus Eriksson

          Issue Links

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              • Assignee:
                marcuse Marcus Eriksson
                Reporter:
                thobbs Tom Hobbs
                Authors:
                Marcus Eriksson
                Reviewers:
                Carl Yeksigian
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                Watchers:
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                Dates

                • Created:
                  Updated:
                  Resolved: