org.apache.parquet.hadoop.metadata.KeyValueMetadataMergeStrategy Maven / Gradle / Ivy
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* 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
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*/
package org.apache.parquet.hadoop.metadata;
import org.apache.parquet.schema.MessageType;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;
import java.util.Set;
import static java.util.Collections.unmodifiableMap;
/**
* Strategy to merge metadata. Possible implementations:
* 1) Expect metadata to be exactly identical. Otherwise throw error (this is the default strategy implementation)
* 2) Custom strategy to merge metadata if the values are not identical. Example: concatenate values.
*/
public interface KeyValueMetadataMergeStrategy extends Serializable {
/**
* @param keyValueMetaData the merged app specific metadata
*/
Map merge(Map> keyValueMetaData);
}