org.apache.hadoop.hive.ql.udf.generic.GenericUDAFResolver Maven / Gradle / Ivy
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* 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,
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package org.apache.hadoop.hive.ql.udf.generic;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
/**
* A Generic User-defined aggregation function (GenericUDAF) for the use with
* Hive.
*
* GenericUDAFResolver is used at compile time. We use GenericUDAFResolver to
* find out the GenericUDAFEvaluator for the parameter types.
*
* @deprecated Use {@link GenericUDAFResolver2} instead.
*/
@Deprecated
public interface GenericUDAFResolver {
/**
* Get the evaluator for the parameter types.
*
* The reason that this function returns an object instead of a class is
* because it is possible that the object needs some configuration (that can
* be serialized). In that case the class of the object has to implement the
* Serializable interface. At execution time, we will deserialize the object
* from the plan and use it to evaluate the aggregations.
*
* If the class of the object does not implement Serializable, then we will
* create a new instance of the class at execution time.
*
* @param parameters
* The types of the parameters. We need the type information to know
* which evaluator class to use.
* @throws SemanticException
*/
GenericUDAFEvaluator getEvaluator(TypeInfo[] parameters)
throws SemanticException;
}