org.bytedeco.arrow_dataset

Class ScannerBuilder

java.lang.Object

org.bytedeco.javacpp.Pointer

org.bytedeco.arrow_dataset.ScannerBuilder

All Implemented Interfaces:

AutoCloseable

@Namespace(value="arrow::dataset")
 @NoOffset
 @Properties(inherit=arrow_dataset.class)
public class ScannerBuilder
extends Pointer

\brief ScannerBuilder is a factory class to construct a Scanner. It is used to pass information, notably a potential filter expression and a subset of columns to materialize.

Nested Class Summary

Nested classes/interfaces inherited from class org.bytedeco.javacpp.Pointer

Pointer.CustomDeallocator, Pointer.Deallocator, Pointer.NativeDeallocator, Pointer.ReferenceCounter

Field Summary

Fields inherited from class org.bytedeco.javacpp.Pointer

address, capacity, limit, position

Constructor Summary

Constructors

Constructor and Description
ScannerBuilder(Dataset dataset, ScanContext context)
ScannerBuilder(Pointer p) Pointer cast constructor.

Method Summary

Modifier and Type	Method and Description
Status	Filter(Expression filter) \brief Set the filter expression to return only rows matching the filter.
ScannerResult	Finish() \brief Return the constructed now-immutable Scanner object
Status	Project(StringVector columns) \brief Set the subset of columns to materialize.
Schema	schema()
Status	UseThreads()
Status	UseThreads(boolean use_threads) \brief Indicate if the Scanner should make use of the available ThreadPool found in ScanContext;

Methods inherited from class org.bytedeco.javacpp.Pointer

address, asBuffer, asByteBuffer, availablePhysicalBytes, calloc, capacity, capacity, close, deallocate, deallocate, deallocateReferences, deallocator, deallocator, equals, fill, formatBytes, free, hashCode, isNull, isNull, limit, limit, malloc, maxBytes, maxPhysicalBytes, memchr, memcmp, memcpy, memmove, memset, offsetof, parseBytes, physicalBytes, position, position, put, realloc, referenceCount, releaseReference, retainReference, setNull, sizeof, toString, totalBytes, totalPhysicalBytes, withDeallocator, zero

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ScannerBuilder

public ScannerBuilder(Pointer p)

Pointer cast constructor. Invokes Pointer.Pointer(Pointer).

ScannerBuilder

public ScannerBuilder(@SharedPtr @ByVal
                      Dataset dataset,
                      @SharedPtr
                      ScanContext context)

Method Detail

Project

@ByVal
public Status Project(@Const @ByRef
                             StringVector columns)

\brief Set the subset of columns to materialize. This subset will be passed down to Sources and corresponding Fragments. The goal is to avoid loading/copying/deserializing columns that will not be required further down the compute chain.

Parameters:

columns - [in] list of columns to project. Order and duplicates will be preserved.

Returns:

Failure if any column name does not exists in the dataset's Schema.

Filter

@ByVal
public Status Filter(@SharedPtr @ByVal
                            Expression filter)

\brief Set the filter expression to return only rows matching the filter. The predicate will be passed down to Sources and corresponding Fragments to exploit predicate pushdown if possible using partition information or Fragment internal metadata, e.g. Parquet statistics.

Parameters:

filter - [in] expression to filter rows with.

Returns:

Failure if any referenced columns does not exist in the dataset's Schema.

UseThreads

@ByVal
public Status UseThreads(@Cast(value="bool")
                                boolean use_threads)

\brief Indicate if the Scanner should make use of the available ThreadPool found in ScanContext;

UseThreads

@ByVal
public Status UseThreads()

Finish

@ByVal
public ScannerResult Finish()

\brief Return the constructed now-immutable Scanner object

schema

@SharedPtr
 @ByVal
public Schema schema()