Tajo
  1. Tajo
  2. TAJO-36

Improve ExternalSortExec with N-merge sort and final pass omission

    Details

    • Type: Improvement Improvement
    • Status: Resolved
    • Priority: Critical Critical
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 0.8
    • Component/s: physical operator
    • Labels:
      None

      Description

      Background:

      The current ExternalSortExec just uses the binary external merge sort algorithm (http://en.wikipedia.org/wiki/External_sorting#External_merge_sort). In other words, for each pass, ExternalSortExec just merges two files into one sorted file.

      Proposal:
      The goal of this proposal is to improve ExternalSortExec with the following improvements:

      • N-merge sort - we can merge N files though more memory at each pass. It will reduce the number of passes. Consequently, it will reduces considerable I/O overheads.
      • the final pass omission - a physical operator is pipelined by the parent operator. The final pass of the merge sort must also be invoked by the parent physical operator. So, we can omit the final pass of the merge sort.
      1. TAJO-36.patch
        100 kB
        Hyunsik Choi
      2. TAJO-36_final.patch
        102 kB
        Hyunsik Choi
      3. TAJO-36_20140205_00:21:44.patch
        103 kB
        Hyunsik Choi
      4. TAJO-36_140204_172847.patch
        102 kB
        Hyunsik Choi
      5. TAJO-36_140204_163419.patch
        100 kB
        Hyunsik Choi

        Issue Links

          Activity

          No work has yet been logged on this issue.

            People

            • Assignee:
              Hyunsik Choi
              Reporter:
              Hyunsik Choi
            • Votes:
              0 Vote for this issue
              Watchers:
              4 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved:

                Development