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/**
* Copyright 2012 Twitter, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package parquet.column;
import static parquet.column.values.bitpacking.Packer.BIG_ENDIAN;
import static parquet.schema.PrimitiveType.PrimitiveTypeName.INT32;
import static parquet.schema.PrimitiveType.PrimitiveTypeName.BINARY;
import static parquet.schema.PrimitiveType.PrimitiveTypeName.BOOLEAN;
import java.io.IOException;
import parquet.bytes.BytesUtils;
import parquet.column.page.DictionaryPage;
import parquet.column.values.ValuesReader;
import parquet.column.values.bitpacking.ByteBitPackingValuesReader;
import parquet.column.values.boundedint.ZeroIntegerValuesReader;
import parquet.column.values.delta.DeltaBinaryPackingValuesReader;
import parquet.column.values.deltalengthbytearray.DeltaLengthByteArrayValuesReader;
import parquet.column.values.deltastrings.DeltaByteArrayReader;
import parquet.column.values.dictionary.DictionaryValuesReader;
import parquet.column.values.dictionary.PlainValuesDictionary.PlainBinaryDictionary;
import parquet.column.values.dictionary.PlainValuesDictionary.PlainDoubleDictionary;
import parquet.column.values.dictionary.PlainValuesDictionary.PlainFloatDictionary;
import parquet.column.values.dictionary.PlainValuesDictionary.PlainIntegerDictionary;
import parquet.column.values.dictionary.PlainValuesDictionary.PlainLongDictionary;
import parquet.column.values.plain.BinaryPlainValuesReader;
import parquet.column.values.plain.FixedLenByteArrayPlainValuesReader;
import parquet.column.values.plain.BooleanPlainValuesReader;
import parquet.column.values.plain.PlainValuesReader.DoublePlainValuesReader;
import parquet.column.values.plain.PlainValuesReader.FloatPlainValuesReader;
import parquet.column.values.plain.PlainValuesReader.IntegerPlainValuesReader;
import parquet.column.values.plain.PlainValuesReader.LongPlainValuesReader;
import parquet.column.values.rle.RunLengthBitPackingHybridValuesReader;
import parquet.io.ParquetDecodingException;
/**
* encoding of the data
*
* @author Julien Le Dem
*
*/
public enum Encoding {
PLAIN {
@Override
public ValuesReader getValuesReader(ColumnDescriptor descriptor, ValuesType valuesType) {
switch (descriptor.getType()) {
case BOOLEAN:
return new BooleanPlainValuesReader();
case BINARY:
return new BinaryPlainValuesReader();
case FLOAT:
return new FloatPlainValuesReader();
case DOUBLE:
return new DoublePlainValuesReader();
case INT32:
return new IntegerPlainValuesReader();
case INT64:
return new LongPlainValuesReader();
case FIXED_LEN_BYTE_ARRAY:
return new FixedLenByteArrayPlainValuesReader(descriptor.getTypeLength());
default:
throw new ParquetDecodingException("no plain reader for type " + descriptor.getType());
}
}
},
/**
* Actually a combination of bit packing and run length encoding.
* TODO: Should we rename this to be more clear?
*/
RLE {
@Override
public ValuesReader getValuesReader(ColumnDescriptor descriptor, ValuesType valuesType) {
int bitWidth = BytesUtils.getWidthFromMaxInt(getMaxLevel(descriptor, valuesType));
if(bitWidth == 0) {
return new ZeroIntegerValuesReader();
}
return new RunLengthBitPackingHybridValuesReader(bitWidth);
}
},
/**
* This is no longer used, and has been replaced by {@link #RLE}
* which is combination of bit packing and rle
*/
@Deprecated
BIT_PACKED {
@Override
public ValuesReader getValuesReader(ColumnDescriptor descriptor, ValuesType valuesType) {
return new ByteBitPackingValuesReader(getMaxLevel(descriptor, valuesType), BIG_ENDIAN);
}
},
PLAIN_DICTIONARY {
@Override
public ValuesReader getDictionaryBasedValuesReader(ColumnDescriptor descriptor, ValuesType valuesType, Dictionary dictionary) {
switch (descriptor.getType()) {
case BINARY:
case INT64:
case DOUBLE:
case INT32:
case FLOAT:
return new DictionaryValuesReader(dictionary);
default:
throw new ParquetDecodingException("Dictionary encoding not supported for type: " + descriptor.getType());
}
}
@Override
public Dictionary initDictionary(ColumnDescriptor descriptor, DictionaryPage dictionaryPage) throws IOException {
switch (descriptor.getType()) {
case BINARY:
return new PlainBinaryDictionary(dictionaryPage);
case INT64:
return new PlainLongDictionary(dictionaryPage);
case DOUBLE:
return new PlainDoubleDictionary(dictionaryPage);
case INT32:
return new PlainIntegerDictionary(dictionaryPage);
case FLOAT:
return new PlainFloatDictionary(dictionaryPage);
default:
throw new ParquetDecodingException("Dictionary encoding not supported for type: " + descriptor.getType());
}
}
@Override
public boolean usesDictionary() {
return true;
}
},
/**
* Delta encoding for integers. This can be used for int columns and works best
* on sorted data
*/
DELTA_BINARY_PACKED {
@Override
public ValuesReader getValuesReader(ColumnDescriptor descriptor, ValuesType valuesType) {
if(descriptor.getType() != INT32) {
throw new ParquetDecodingException("Encoding DELTA_BINARY_PACKED is only supported for type INT32");
}
return new DeltaBinaryPackingValuesReader();
}
},
/**
* Encoding for byte arrays to separate the length values and the data. The lengths
* are encoded using DELTA_BINARY_PACKED
*/
DELTA_LENGTH_BYTE_ARRAY {
@Override
public ValuesReader getValuesReader(ColumnDescriptor descriptor,
ValuesType valuesType) {
if (descriptor.getType() != BINARY) {
throw new ParquetDecodingException("Encoding DELTA_LENGTH_BYTE_ARRAY is only supported for type BINARY");
}
return new DeltaLengthByteArrayValuesReader();
}
},
/**
* Incremental-encoded byte array. Prefix lengths are encoded using DELTA_BINARY_PACKED.
* Suffixes are stored as delta length byte arrays.
*/
DELTA_BYTE_ARRAY {
@Override
public ValuesReader getValuesReader(ColumnDescriptor descriptor,
ValuesType valuesType) {
if (descriptor.getType() != BINARY) {
throw new ParquetDecodingException("Encoding DELTA_BYTE_ARRAY is only supported for type BINARY");
}
return new DeltaByteArrayReader();
}
},
/**
* Dictionary encoding: the ids are encoded using the RLE encoding
*/
RLE_DICTIONARY;
int getMaxLevel(ColumnDescriptor descriptor, ValuesType valuesType) {
int maxLevel;
switch (valuesType) {
case REPETITION_LEVEL:
maxLevel = descriptor.getMaxRepetitionLevel();
break;
case DEFINITION_LEVEL:
maxLevel = descriptor.getMaxDefinitionLevel();
break;
case VALUES:
if(descriptor.getType() == BOOLEAN) {
maxLevel = 1;
break;
}
default:
throw new ParquetDecodingException("Unsupported encoding for values: " + this);
}
return maxLevel;
}
/**
* @return whether this encoding requires a dictionary
*/
public boolean usesDictionary() {
return false;
}
/**
* initializes a dictionary from a page
* @param dictionaryPage
* @return the corresponding dictionary
*/
public Dictionary initDictionary(ColumnDescriptor descriptor, DictionaryPage dictionaryPage) throws IOException {
throw new UnsupportedOperationException(this.name() + " does not support dictionary");
}
/**
* To read decoded values that don't require a dictionary
*
* @param descriptor the column to read
* @param valuesType the type of values
* @return the proper values reader for the given column
* @throw {@link UnsupportedOperationException} if the encoding is dictionary based
*/
public ValuesReader getValuesReader(ColumnDescriptor descriptor, ValuesType valuesType) {
throw new UnsupportedOperationException("Error decoding " + descriptor + ". " + this.name() + " is dictionary based");
}
/**
* To read decoded values that require a dictionary
*
* @param descriptor the column to read
* @param valuesType the type of values
* @param dictionary the dictionary
* @return the proper values reader for the given column
* @throw {@link UnsupportedOperationException} if the encoding is not dictionary based
*/
public ValuesReader getDictionaryBasedValuesReader(ColumnDescriptor descriptor, ValuesType valuesType, Dictionary dictionary) {
throw new UnsupportedOperationException(this.name() + " is not dictionary based");
}
}
