org.apache.parquet.column

Interface ColumnReader

public interface ColumnReader

Reader for (repetition level, definition level, values) triplets. At any given point in time, a ColumnReader points to a single (r, d, v) triplet. In order to move to the next triplet, call consume(). Depending on the type and the encoding of the column only a subset of the get* methods are implemented. Dictionary specific methods enable the upper layers to read the dictionary IDs without decoding the data. In particular the Converter will decode the strings in the dictionary only once and iterate on the dictionary IDs instead of the values.

Each iteration looks at the current definition level and value as well as the next repetition level:
• The current definition level defines if the value is null.
• If the value is defined we can read it with the correct get*() method.
• Looking ahead to the next repetition determines what is the next column to read for in the FSA.

Author:

Julien Le Dem

Method Summary

Methods

Modifier and Type	Method and Description
void	consume() Consume the current triplet, moving to the next value.
Binary	getBinary()
boolean	getBoolean()
int	getCurrentDefinitionLevel()
int	getCurrentRepetitionLevel() must return 0 when isFullyConsumed() == true
int	getCurrentValueDictionaryID() available when the underlying encoding is dictionary based
ColumnDescriptor	getDescriptor()
double	getDouble()
float	getFloat()
int	getInteger()
long	getLong()
long	getTotalValueCount()
void	skip() Skip the current value
void	writeCurrentValueToConverter() writes the current value to the converter

Method Detail

getTotalValueCount

long getTotalValueCount()

Returns:

the totalCount of values to be consumed

consume

void consume()

Consume the current triplet, moving to the next value.

getCurrentRepetitionLevel

int getCurrentRepetitionLevel()

must return 0 when isFullyConsumed() == true

Returns:

the repetition level for the current value

getCurrentDefinitionLevel

int getCurrentDefinitionLevel()

Returns:

the definition level for the current value

writeCurrentValueToConverter

void writeCurrentValueToConverter()

writes the current value to the converter

skip

void skip()

Skip the current value

getCurrentValueDictionaryID

int getCurrentValueDictionaryID()

available when the underlying encoding is dictionary based

Returns:

the dictionary id for the current value

getInteger

int getInteger()

Returns:

the current value

getBoolean

boolean getBoolean()

Returns:

the current value

getLong

long getLong()

Returns:

the current value

getBinary

Binary getBinary()

Returns:

the current value

getFloat

float getFloat()

Returns:

the current value

getDouble

double getDouble()

Returns:

the current value

getDescriptor

ColumnDescriptor getDescriptor()

Returns:

Descriptor of the column.