Package ai.rapids.cudf

Class HashJoin

java.lang.Object
ai.rapids.cudf.HashJoin
All Implemented Interfaces:
AutoCloseable
public class HashJoin extends Object implements AutoCloseable
This class represents a hash table built from the join keys of the right-side table for a join operation. This hash table can then be reused across a series of left probe tables to compute gather maps for joins more efficiently when the right-side table is not changing. It can also be used to query the output row count of a join and then pass that result to the operation that generates the join gather maps to avoid redundant computation when the output row count must be checked before manifesting the join gather maps.

  • Constructor Summary

    Constructors
    Constructor
    Description
    HashJoin(Table buildKeys, boolean compareNulls)
    Construct a hash table for a join from a table representing the join key columns from the right-side table in the join.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    close()
     
    boolean
    getCompareNulls()
    Returns true if the hash table was built to match on nulls otherwise false.
    long
    getNumberOfColumns()
    Get the number of join key columns for the table that was used to generate the has table.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • HashJoin

      public HashJoin(Table buildKeys, boolean compareNulls)
      Construct a hash table for a join from a table representing the join key columns from the right-side table in the join. The resulting instance must be closed to release the GPU resources associated with the instance.
      Parameters:
      buildKeys - table view containing the join keys for the right-side join table
      compareNulls - true if null key values should match otherwise false

  • Method Details

    • close

      public void close()
      Specified by:
      close in interface AutoCloseable

    • getNumberOfColumns

      public long getNumberOfColumns()
      Get the number of join key columns for the table that was used to generate the has table.

    • getCompareNulls

      public boolean getCompareNulls()
      Returns true if the hash table was built to match on nulls otherwise false.