Details

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

      Description

      Build a merging receiver operator which combines a number of incoming batches into a single outgoing batch.

      Overview

      Incoming batches are individually presorted before reaching this operator, so a priority queue is built with each value to determine which batch contains the next record. When the next value is removed from the priority queue, the underlying record is copied from the underlying ValueVectors to the outgoing VectorContainer.

      The comparator for the priority queue is generated based on the supplied LogicalExpression (e.g. a single ValueVectorReadExpression).

      Example

      The following example illustrates a distributed count operation, where each remote fragment counts a subset of the data and the root fragment produces a sum of each count aggregate.

      Data Flow

      RecordReader
        |
        +-> Sort
             |
             +-> StreamingAggregate(COUNT)
                    |
                    +-> MergingPartitionExchange
                           |
                           +-> StreamingAggregate(SUM)
                                  |
                                  +-> UnionExchange
                                         |
                                         +-> Screen
      

      Control Flow

      Root Fragment
      -------------
      Screen
         |
         +->UnionExchange
               | | |
               | | +->AggSum
               | |      |
               | |      +->MergingReceiver
               | |
               | +--->AggSum
               |        |
               |        +->MergingReceiver
               |
               +----->AggSum
                        |
                        +->MergingReceiver
                   ...
      
      Remote Fragment
      ---------------
      PartitionSender
             |
             +->AggCount
                   |
                   +->Sort
                       |
                       +->Reader
      

        Activity

          People

          • Assignee:
            Ben Becker
            Reporter:
            Jacques Nadeau
          • Votes:
            0 Vote for this issue
            Watchers:
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            Dates

            • Created:
              Updated:
              Resolved:

              Development