org.apache.parquet.column.values.dictionary

Class DictionaryValuesReader

java.lang.Object

org.apache.parquet.column.values.ValuesReader

org.apache.parquet.column.values.dictionary.DictionaryValuesReader

public class DictionaryValuesReader
extends ValuesReader

Reads values that have been dictionary encoded

Author:

Julien Le Dem

Constructor Summary

Constructors

Constructor and Description
DictionaryValuesReader(Dictionary dictionary)

Method Summary

Methods

Modifier and Type	Method and Description
void	initFromPage(int valueCount, byte[] page, int offset) Called to initialize the column reader from a part of a page.
Binary	readBytes()
double	readDouble()
float	readFloat()
int	readInteger()
long	readLong()
int	readValueDictionaryId() usable when the encoding is dictionary based
void	skip() Skips the next value in the page

Methods inherited from class org.apache.parquet.column.values.ValuesReader

getNextOffset, readBoolean

Methods inherited from class java.lang.Object

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

Constructor Detail

DictionaryValuesReader

public DictionaryValuesReader(Dictionary dictionary)

Method Detail

initFromPage

public void initFromPage(int valueCount,
                byte[] page,
                int offset)
                  throws IOException

Description copied from class: ValuesReader

Called to initialize the column reader from a part of a page. The underlying implementation knows how much data to read, so a length is not provided. Each page may contain several sections:

• repetition levels column
• definition levels column
• data column

This function is called with 'offset' pointing to the beginning of one of these sections, and should return the offset to the section following it.

Specified by:

initFromPage in class ValuesReader

Parameters:

valueCount - count of values in this page

page - the array to read from containing the page data (repetition levels, definition levels, data)

offset - where to start reading from in the page

Throws:

IOException

readValueDictionaryId

public int readValueDictionaryId()

Description copied from class: ValuesReader

usable when the encoding is dictionary based

Overrides:

readValueDictionaryId in class ValuesReader

Returns:

the id of the next value from the page

readBytes

public Binary readBytes()

Overrides:

readBytes in class ValuesReader

Returns:

the next Binary from the page

readFloat

public float readFloat()

Overrides:

readFloat in class ValuesReader

Returns:

the next float from the page

readDouble

public double readDouble()

Overrides:

readDouble in class ValuesReader

Returns:

the next double from the page

readInteger

public int readInteger()

Overrides:

readInteger in class ValuesReader

Returns:

the next integer from the page

readLong

public long readLong()

Overrides:

readLong in class ValuesReader

Returns:

the next long from the page

skip

public void skip()

Description copied from class: ValuesReader

Skips the next value in the page

Specified by:

skip in class ValuesReader