org.apache.arrow.vector.ipc

Class ArrowFileReader

java.lang.Object

org.apache.arrow.vector.ipc.ArrowReader

org.apache.arrow.vector.ipc.ArrowFileReader

All Implemented Interfaces:

AutoCloseable, DictionaryProvider

public class ArrowFileReader
extends ArrowReader

An implementation of ArrowReader that reads the standard arrow binary file format.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.arrow.vector.dictionary.DictionaryProvider

DictionaryProvider.MapDictionaryProvider

Field Summary

Fields inherited from class org.apache.arrow.vector.ipc.ArrowReader

allocator, dictionaries

Constructor Summary

Constructors

Constructor and Description
ArrowFileReader(SeekableByteChannel in, BufferAllocator allocator)
ArrowFileReader(SeekableReadChannel in, BufferAllocator allocator)

Method Summary

Modifier and Type	Method and Description
long	bytesRead() Return the number of bytes read from the ReadChannel.
protected void	closeReadSource() Close the underlying read source.
List<ArrowBlock>	getDictionaryBlocks()
Map<String,String>	getMetaData() Get custom metadata.
List<ArrowBlock>	getRecordBlocks() Returns the ArrowBlock metadata from the file.
void	initialize() Reads the schema and initializes the vectors.
boolean	loadNextBatch() Returns true if a batch was read, false if no more batches.
boolean	loadRecordBatch(ArrowBlock block) Loads record batch for the given block.
ArrowDictionaryBatch	readDictionary() Read a dictionary batch from the source, will be invoked after the schema has been read and called N times, where N is the number of dictionaries indicated by the schema Fields.
protected Schema	readSchema() Read the Schema from the source, will be invoked at the beginning the initialization.

Methods inherited from class org.apache.arrow.vector.ipc.ArrowReader

close, close, ensureInitialized, getDictionaryVectors, getVectorSchemaRoot, loadDictionary, loadRecordBatch, lookup, prepareLoadNextBatch

Methods inherited from class java.lang.Object

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

Constructor Detail

ArrowFileReader

public ArrowFileReader(SeekableReadChannel in,
                       BufferAllocator allocator)

ArrowFileReader

public ArrowFileReader(SeekableByteChannel in,
                       BufferAllocator allocator)

Method Detail

bytesRead

public long bytesRead()

Description copied from class: ArrowReader

Return the number of bytes read from the ReadChannel.

Specified by:

bytesRead in class ArrowReader

Returns:

number of bytes read

closeReadSource

protected void closeReadSource()
                        throws IOException

Description copied from class: ArrowReader

Close the underlying read source.

Specified by:

closeReadSource in class ArrowReader

Throws:

IOException - on error

readSchema

protected Schema readSchema()
                     throws IOException

Description copied from class: ArrowReader

Read the Schema from the source, will be invoked at the beginning the initialization.

Specified by:

readSchema in class ArrowReader

Returns:

the read Schema

Throws:

IOException - on error

initialize

public void initialize()
                throws IOException

Description copied from class: ArrowReader

Reads the schema and initializes the vectors.

Overrides:

initialize in class ArrowReader

Throws:

IOException

getMetaData

public Map<String,String> getMetaData()

Get custom metadata.

readDictionary

public ArrowDictionaryBatch readDictionary()
                                    throws IOException

Read a dictionary batch from the source, will be invoked after the schema has been read and called N times, where N is the number of dictionaries indicated by the schema Fields.

Returns:

the read ArrowDictionaryBatch

Throws:

IOException - on error

loadNextBatch

public boolean loadNextBatch()
                      throws IOException

Returns true if a batch was read, false if no more batches.

Specified by:

loadNextBatch in class ArrowReader

Returns:

true if a batch was read, false on EOS

Throws:

IOException - on error

getDictionaryBlocks

public List<ArrowBlock> getDictionaryBlocks()
                                     throws IOException

Throws:

IOException

getRecordBlocks

public List<ArrowBlock> getRecordBlocks()
                                 throws IOException

Returns the ArrowBlock metadata from the file.

Throws:

IOException

loadRecordBatch

public boolean loadRecordBatch(ArrowBlock block)
                        throws IOException

Loads record batch for the given block.

Throws:

IOException