Details

    • Type: New Feature New Feature
    • Status: Resolved
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 0.4.0
    • Component/s: None
    • Labels:
      None

      Description

      This operator will allow sorting data that is larger than the size of memory by spilling to disk when necessary.

      Also as part of this jira, I will implement a new merge sort algorithm that will hopefully better utilize cluster resources than our current sort, which is based on Quicksort. The problem with quicksort is that we can't do any sorting until all of the batches have arrived. But this will often result in very low CPU utilization while the data is read from disk, followed by a period of very high CPU usage.

      The external sort will include sorting each batch individually when it arrives. In the case where no spills occur, it makes sense to take advantage of the fact that the batches are already sorted, but doing the an N-way merge, as is done when there are spills, is not the most effective way to do this, (according to some tests I have done). What will be done in this case, rather than an N-way merge using a heap, we will do a variation of natural merge sort, which amounts to essentially a staged, 2-way merge of the incoming (sorted) batches.

      1. DRILL-386.patch
        105 kB
        Steven Phillips
      2. DRILL-386.patch
        105 kB
        Steven Phillips
      3. DRILL-386.patch
        103 kB
        Steven Phillips
      4. DRILL-386.patch
        112 kB
        Steven Phillips

        Activity

        Hide
        Steven Phillips added a comment -

        addressed code review comments and rebased off latest master.

        Show
        Steven Phillips added a comment - addressed code review comments and rebased off latest master.
        Hide
        Steven Phillips added a comment -

        Rebased on current master.

        Show
        Steven Phillips added a comment - Rebased on current master.
        Hide
        Steven Phillips added a comment -

        Fixed a memory leak

        Show
        Steven Phillips added a comment - Fixed a memory leak
        Hide
        Jacques Nadeau added a comment -

        Added in aee7972.

        Show
        Jacques Nadeau added a comment - Added in aee7972.

          People

          • Assignee:
            Steven Phillips
            Reporter:
            Steven Phillips
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            Dates

            • Created:
              Updated:
              Resolved:

              Development