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 and 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 and 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 Detail

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 Detail

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.