cudf::distinct_hash_join Class Reference

Distinct hash join that builds hash table in creation and probes results in subsequent *_join member functions. More...

#include <join.hpp>

Public Member Functions
	distinct_hash_join (distinct_hash_join const &)=delete
	distinct_hash_join (distinct_hash_join &&)=delete
distinct_hash_join &	operator= (distinct_hash_join const &)=delete
distinct_hash_join &	operator= (distinct_hash_join &&)=delete
	distinct_hash_join (cudf::table_view const &build, null_equality compare_nulls=null_equality::EQUAL, rmm::cuda_stream_view stream=cudf::get_default_stream())
	Constructs a distinct hash join object for subsequent probe calls. More...
std::pair< std::unique_ptr< rmm::device_uvector< size_type > >, std::unique_ptr< rmm::device_uvector< size_type > > >	inner_join (cudf::table_view const &probe, rmm::cuda_stream_view stream=cudf::get_default_stream(), rmm::device_async_resource_ref mr=cudf::get_current_device_resource_ref()) const
	Returns the row indices that can be used to construct the result of performing an inner join between two tables. More...
std::unique_ptr< rmm::device_uvector< size_type > >	left_join (cudf::table_view const &probe, rmm::cuda_stream_view stream=cudf::get_default_stream(), rmm::device_async_resource_ref mr=cudf::get_current_device_resource_ref()) const
	Returns the build table indices that can be used to construct the result of performing a left join between two tables. More...

Detailed Description

Distinct hash join that builds hash table in creation and probes results in subsequent *_join member functions.

This class enables the distinct hash join scheme that builds hash table once, and probes as many times as needed (possibly in parallel).

Note

Behavior is undefined if the build table contains duplicates.

All NaNs are considered as equal

Definition at line 477 of file join.hpp.

Constructor & Destructor Documentation

distinct_hash_join()

cudf::distinct_hash_join::distinct_hash_join	(	cudf::table_view const &	build,
		null_equality	compare_nulls = null_equality::EQUAL,
		rmm::cuda_stream_view	stream = cudf::get_default_stream()
	)

Constructs a distinct hash join object for subsequent probe calls.

Parameters

build	The build table that contains distinct elements
compare_nulls	Controls whether null join-key values should match or not
stream	CUDA stream used for device memory operations and kernel launches

Member Function Documentation

inner_join()

std::pair<std::unique_ptr<rmm::device_uvector<size_type> >, std::unique_ptr<rmm::device_uvector<size_type> > > cudf::distinct_hash_join::inner_join	(	cudf::table_view const &	probe,
		rmm::cuda_stream_view	stream = cudf::get_default_stream(),
		rmm::device_async_resource_ref	mr = cudf::get_current_device_resource_ref()
	)		const

Returns the row indices that can be used to construct the result of performing an inner join between two tables.

See also

cudf::inner_join().

Parameters

probe	The probe table, from which the keys are probed
stream	CUDA stream used for device memory operations and kernel launches
mr	Device memory resource used to allocate the returned indices' device memory.

Returns

A pair of columns [probe_indices, build_indices] that can be used to construct the result of performing an inner join between two tables with build and probe as the join keys.

left_join()

std::unique_ptr<rmm::device_uvector<size_type> > cudf::distinct_hash_join::left_join	(	cudf::table_view const &	probe,
		rmm::cuda_stream_view	stream = cudf::get_default_stream(),
		rmm::device_async_resource_ref	mr = cudf::get_current_device_resource_ref()
	)		const

Returns the build table indices that can be used to construct the result of performing a left join between two tables.

Note

For a given row index i of the probe table, the resulting build_indices[i] contains the row index of the matched row from the build table if there is a match. Otherwise, contains JoinNoneValue.

Parameters

probe	The probe table, from which the keys are probed
stream	CUDA stream used for device memory operations and kernel launches
mr	Device memory resource used to allocate the returned table and columns' device memory.

Returns

A build_indices column that can be used to construct the result of performing a left join between two tables with build and probe as the join keys.

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The documentation for this class was generated from the following file:

• join.hpp