org.apache.avro.hadoop.file

Class SortedKeyValueFile.Reader<K,V>

java.lang.Object

org.apache.avro.hadoop.file.SortedKeyValueFile.Reader<K,V>

Type Parameters:

K - The key type.

V - The value type.

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<AvroKeyValue<K,V>>

Enclosing class:

SortedKeyValueFile

public static class SortedKeyValueFile.Reader<K,V>
extends Object
implements Closeable, Iterable<AvroKeyValue<K,V>>

Reads a SortedKeyValueFile by loading the key index into memory.

When doing a lookup, this reader finds the correct block in the data file using the key index. It performs a single disk seek to the block and loads the entire block into memory. The block is scanned until the key is found or is determined not to exist.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SortedKeyValueFile.Reader.Options A class to encapsulate the options of a Reader.

Constructor Summary

Constructors

Constructor and Description
SortedKeyValueFile.Reader(SortedKeyValueFile.Reader.Options options) Constructs a reader.

Method Summary

Methods

Modifier and Type	Method and Description
void	close()
V	get(K key) Gets the first value associated with a given key, or null if it is not found.
Iterator<AvroKeyValue<K,V>>	iterator() Returns an iterator starting at the current position in the file.

Methods inherited from class java.lang.Object

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

Constructor Detail

SortedKeyValueFile.Reader

public SortedKeyValueFile.Reader(SortedKeyValueFile.Reader.Options options)
                          throws IOException

Constructs a reader.

Parameters:

options - The options.

Throws:

IOException - If there is an error.

Method Detail

get

public V get(K key)
      throws IOException

Gets the first value associated with a given key, or null if it is not found.

This method will move the current position in the file to the record immediately following the requested key.

Parameters:

key - The key to look up.

Returns:

The value associated with the key, or null if not found.

Throws:

IOException - If there is an error.

iterator

public Iterator<AvroKeyValue<K,V>> iterator()

Returns an iterator starting at the current position in the file.

Use the get() method to move the current position.

Note that this iterator is shared with other clients of the file; it does not contain a separate pointer into the file.

Specified by:

iterator in interface Iterable<AvroKeyValue<K,V>>

Returns:

An iterator.

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException