spark ParquetDictionary 源码
spark ParquetDictionary 代码
文件路径：/sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/ParquetDictionary.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.spark.sql.execution.datasources.parquet;
import org.apache.spark.sql.execution.vectorized.Dictionary;
import java.math.BigInteger;
public final class ParquetDictionary implements Dictionary {
private org.apache.parquet.column.Dictionary dictionary;
private boolean needTransform = false;
public ParquetDictionary(org.apache.parquet.column.Dictionary dictionary, boolean needTransform) {
this.dictionary = dictionary;
this.needTransform = needTransform;
}
@Override
public int decodeToInt(int id) {
if (needTransform) {
return (int) dictionary.decodeToLong(id);
} else {
return dictionary.decodeToInt(id);
}
}
@Override
public long decodeToLong(int id) {
if (needTransform) {
// For unsigned int32, it stores as dictionary encoded signed int32 in Parquet
// whenever dictionary is available.
// Here we lazily decode it to the original signed int value then convert to long(unit32).
return Integer.toUnsignedLong(dictionary.decodeToInt(id));
} else {
return dictionary.decodeToLong(id);
}
}
@Override
public float decodeToFloat(int id) {
return dictionary.decodeToFloat(id);
}
@Override
public double decodeToDouble(int id) {
return dictionary.decodeToDouble(id);
}
@Override
public byte[] decodeToBinary(int id) {
if (needTransform) {
// For unsigned int64, it stores as dictionary encoded signed int64 in Parquet
// whenever dictionary is available.
// Here we lazily decode it to the original signed long value then convert to decimal(20, 0).
long signed = dictionary.decodeToLong(id);
return new BigInteger(Long.toUnsignedString(signed)).toByteArray();
} else {
return dictionary.decodeToBinary(id).getBytes();
}
}
}
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