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  1. HBase
  2. HBASE-13109

Make better SEEK vs SKIP decisions during scanning

    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 1.0.1, 1.1.0, 0.98.12, 2.0.0
    • Component/s: None
    • Labels:
      None
    • Hadoop Flags:
      Reviewed

      Description

      I'm re-purposing this issue to add a heuristic as to when to SEEK and when to SKIP Cells. This has come up in various issues, and I think I have a way to finally fix this now. HBASE-9778, HBASE-12311, and friends are related.

      — Old description —

      This is a continuation of HBASE-9778.
      We've seen a scenario of a very slow scan over a region using a timerange that happens to fall after the ts of any Cell in the region.
      Turns out we spend a lot of time seeking.

      Tested with a 5 column table, and the scan is 5x faster when the timerange falls before all Cells' ts.
      We can use the lookahead hint introduced in HBASE-9778 to do opportunistic SKIPing before we actually seek.

        Attachments

        1. 13109-0.98-v5.txt
          27 kB
          Lars Hofhansl
        2. 13109-trunk-v5.txt
          35 kB
          Lars Hofhansl
        3. 13109-0.98-v4.txt
          27 kB
          Lars Hofhansl
        4. nextIndexKVChange_new.patch
          6 kB
          ramkrishna.s.vasudevan
        5. 13109-trunk-v4.txt
          25 kB
          Lars Hofhansl
        6. 13109-trunk-v3.txt
          24 kB
          Lars Hofhansl
        7. 13109-trunk-v2.txt
          24 kB
          Lars Hofhansl
        8. 13109-trunk.txt
          27 kB
          Lars Hofhansl

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              • Assignee:
                lhofhansl Lars Hofhansl
                Reporter:
                lhofhansl Lars Hofhansl
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                Dates

                • Created:
                  Updated:
                  Resolved: