org.apache.parquet.column

Enum Encoding

java.lang.Object

java.lang.Enum<Encoding>

org.apache.parquet.column.Encoding

All Implemented Interfaces:

Serializable, Comparable<Encoding>

public enum Encoding
extends Enum<Encoding>

encoding of the data

Enum Constant Summary

Enum Constants

Enum Constant and Description
BIT_PACKED Deprecated. This is no longer used, and has been replaced by RLE which is combination of bit packing and rle
DELTA_BINARY_PACKED Delta encoding for integers.
DELTA_BYTE_ARRAY Incremental-encoded byte array.
DELTA_LENGTH_BYTE_ARRAY Encoding for byte arrays to separate the length values and the data.
PLAIN
PLAIN_DICTIONARY Deprecated. now replaced by RLE_DICTIONARY for the data page encoding and PLAIN for the dictionary page encoding
RLE Actually a combination of bit packing and run length encoding.
RLE_DICTIONARY Dictionary encoding: the ids are encoded using the RLE encoding

Method Summary

Modifier and Type	Method and Description
ValuesReader	getDictionaryBasedValuesReader(ColumnDescriptor descriptor, ValuesType valuesType, Dictionary dictionary) To read decoded values that require a dictionary
ValuesReader	getValuesReader(ColumnDescriptor descriptor, ValuesType valuesType) To read decoded values that don't require a dictionary
Dictionary	initDictionary(ColumnDescriptor descriptor, DictionaryPage dictionaryPage) initializes a dictionary from a page
boolean	usesDictionary()
static Encoding	valueOf(String name) Returns the enum constant of this type with the specified name.
static Encoding[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

PLAIN

public static final Encoding PLAIN

RLE

public static final Encoding RLE

Actually a combination of bit packing and run length encoding. TODO: Should we rename this to be more clear?

BIT_PACKED

@Deprecated
public static final Encoding BIT_PACKED

Deprecated. This is no longer used, and has been replaced by RLE which is combination of bit packing and rle

PLAIN_DICTIONARY

@Deprecated
public static final Encoding PLAIN_DICTIONARY

Deprecated. now replaced by RLE_DICTIONARY for the data page encoding and PLAIN for the dictionary page encoding

DELTA_BINARY_PACKED

public static final Encoding DELTA_BINARY_PACKED

Delta encoding for integers. This can be used for int columns and works best on sorted data

DELTA_LENGTH_BYTE_ARRAY

public static final Encoding DELTA_LENGTH_BYTE_ARRAY

Encoding for byte arrays to separate the length values and the data. The lengths are encoded using DELTA_BINARY_PACKED

DELTA_BYTE_ARRAY

public static final Encoding DELTA_BYTE_ARRAY

Incremental-encoded byte array. Prefix lengths are encoded using DELTA_BINARY_PACKED. Suffixes are stored as delta length byte arrays.

RLE_DICTIONARY

public static final Encoding RLE_DICTIONARY

Dictionary encoding: the ids are encoded using the RLE encoding

Method Detail

values

public static Encoding[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (Encoding c : Encoding.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static Encoding valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

usesDictionary

public boolean usesDictionary()

Returns:

whether this encoding requires a dictionary

initDictionary

public Dictionary initDictionary(ColumnDescriptor descriptor,
                                 DictionaryPage dictionaryPage)
                          throws IOException

initializes a dictionary from a page

Parameters:

descriptor - the column descriptor for the dictionary-encoded column

dictionaryPage - a dictionary page

Returns:

the corresponding dictionary

Throws:

IOException - if there is an exception while reading the dictionary page

UnsupportedOperationException - if the encoding is not dictionary based

getValuesReader

public ValuesReader getValuesReader(ColumnDescriptor descriptor,
                                    ValuesType valuesType)

To read decoded values that don't require a dictionary

Parameters:

descriptor - the column to read

valuesType - the type of values

Returns:

the proper values reader for the given column

Throws:

UnsupportedOperationException - if the encoding is dictionary based

getDictionaryBasedValuesReader

public ValuesReader getDictionaryBasedValuesReader(ColumnDescriptor descriptor,
                                                   ValuesType valuesType,
                                                   Dictionary dictionary)

To read decoded values that require a dictionary

Parameters:

descriptor - the column to read

valuesType - the type of values

dictionary - the dictionary

Returns:

the proper values reader for the given column

Throws:

UnsupportedOperationException - if the encoding is not dictionary based