Module org.apache.arrow.vector

Package org.apache.arrow.vector.dictionary

Class DictionaryHashTable

java.lang.Object

org.apache.arrow.vector.dictionary.DictionaryHashTable

public class DictionaryHashTable
extends Object

HashTable used for Dictionary encoding. It holds two vectors (the vector to encode and dictionary vector) It stores the index in dictionary vector and for a given index in encode vector, it could return dictionary index.

Constructor Summary

Constructors

Constructor	Description
DictionaryHashTable(int initialCapacity, ValueVector dictionary, ArrowBufHasher hasher)	Constructs an empty map with the specified initial capacity and load factor.
DictionaryHashTable(ValueVector dictionary)
DictionaryHashTable(ValueVector dictionary, ArrowBufHasher hasher)

Method Summary

Modifier and Type	Method	Description
void	clear()	Removes all elements from this map, leaving it empty.
int	getIndex(int indexInArray, ValueVector toEncode)	get the corresponding dictionary index with the given index in vector which to encode.
int	size()	Returns the number of mappings in this Map.

Methods inherited from class java.lang.Object

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

Constructor Details

DictionaryHashTable

public DictionaryHashTable(int initialCapacity,
 ValueVector dictionary,
 ArrowBufHasher hasher)

Constructs an empty map with the specified initial capacity and load factor.

DictionaryHashTable

public DictionaryHashTable(ValueVector dictionary,
 ArrowBufHasher hasher)

DictionaryHashTable

public DictionaryHashTable(ValueVector dictionary)

Method Details

getIndex

public int getIndex(int indexInArray,
 ValueVector toEncode)

get the corresponding dictionary index with the given index in vector which to encode.

Parameters:

indexInArray - index in vector.

Returns:

dictionary vector index or -1 if no value equals.

size

public int size()

Returns the number of mappings in this Map.

clear

public void clear()

Removes all elements from this map, leaving it empty.