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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-1293) Add support for out-of-place aggregations
Date Mon, 01 Dec 2014 13:33:12 GMT

    [ https://issues.apache.org/jira/browse/FLINK-1293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14229782#comment-14229782
] 

ASF GitHub Bot commented on FLINK-1293:
---------------------------------------

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/incubator-flink/pull/243#discussion_r21088163
  
    --- Diff: flink-java/src/main/java/org/apache/flink/api/java/aggregation/AggregationOperatorFactory.java
---
    @@ -0,0 +1,297 @@
    +/*
    + * 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.flink.api.java.aggregation;
    +
    +import static java.lang.String.format;
    +import static java.util.Arrays.asList;
    +import static org.apache.flink.api.java.aggregation.Aggregations.key;
    +
    +import java.util.ArrayList;
    +import java.util.List;
    +import java.util.Vector;
    +
    +import org.apache.commons.lang3.ArrayUtils;
    +import org.apache.commons.lang3.Validate;
    +import org.apache.flink.api.common.typeinfo.BasicTypeInfo;
    +import org.apache.flink.api.common.typeinfo.TypeInformation;
    +import org.apache.flink.api.java.DataSet;
    +import org.apache.flink.api.java.aggregation.AggregationFunction.ResultTypeBehavior;
    +import org.apache.flink.api.java.operators.AggregationOperator;
    +import org.apache.flink.api.java.operators.UnsortedGrouping;
    +import org.apache.flink.api.java.tuple.Tuple;
    +import org.apache.flink.api.java.typeutils.TupleTypeInfo;
    +import org.apache.flink.api.java.typeutils.TupleTypeInfoBase;
    +
    +import com.google.common.primitives.Ints;
    +
    +/**
    + * Factory method container to construct an
    + * {@link AggregationOperator} from a {@link DataSet} or
    + * {@link UnsortedGrouping}.
    + * 
    + * <p>The factory performs the following tasks:
    + * 
    + * <ol>
    + *  <li>Decompose composite aggregation functions into intermediates.
    + *  <li>Insert missing key aggregation function for any group keys. 
    + *  <li>Set intermediate, and output position for each aggregation function.
    + *  <li>Map any group keys to their position in the intermediate tuple.
    + *  <li>Compute the types of intermediate tuple and aggregation result.
    + *  <li>Create the aggregation operator.
    + * </ol>
    + *
    + * <p>Note: Tasks are implemented in a member class in order to
    + * facilitate testing. 
    + */
    +public class AggregationOperatorFactory {
    +	
    +	private static final AggregationOperatorFactory INSTANCE = new AggregationOperatorFactory();
    +	private AggregationFunctionPreprocessor aggregationFunctionPreprocessor = new AggregationFunctionPreprocessor();
    +	private ResultTypeFactory resultTypeFactory = new ResultTypeFactory();
    +	
    +	
    +	/**
    +	 * Construct an {@link AggregationOperator} that implements the
    +	 * aggregation functions listed in {@code functions} on the
    +	 * (ungrouped) DataSet {@code input}. 
    +	 * @param input	An (ungrouped) DataSet.
    +	 * @param functions The aggregation functions that should be computed.
    +	 * @return An AggregationOperator representing the specified aggregations.
    +	 */
    +	public <T, R extends Tuple> AggregationOperator<T, R> aggregate(DataSet<T>
input, AggregationFunction<?, ?>[] functions) {
    +		AggregationOperator<T, R> op = createAggregationOperator(input, new int[0], functions);
    +		return op;
    +	}
    +
    +	/**
    +	 * Construct an {@link AggregationOperator} that implements the
    +	 * aggregation functions listed in {@code functions} on the grouped
    +	 * DataSet {@code input}.
    +	 * 
    +	 * <p>If there are no {@link Aggregations.keys} specified in
    +	 * {@code functions} then a {@code key()} aggregation function is
    +	 * inserted for each group key.
    +	 *  
    +	 * @param input	An grouped DataSet.
    +	 * @param functions The aggregation functions that should be computed.
    +	 * @return An AggregationOperator representing the specified aggregations.
    +	 */
    +	public <T, R extends Tuple> AggregationOperator<T, R> aggregate(UnsortedGrouping<T>
grouping, AggregationFunction<?, ?>[] functions) {
    +		DataSet<T> input = grouping.getDataSet();
    +		int[] groupKeys = grouping.getKeys().computeLogicalKeyPositions();
    +		AggregationOperator<T, R> op = createAggregationOperator(input, groupKeys, functions);
    +		return op;
    +	}
    +	
    +	// TODO if sum and/or count are present, use these to compute average
    --- End diff --
    
    TODO solved? 
    Is count reused for multiple average aggregations?


> Add support for out-of-place aggregations
> -----------------------------------------
>
>                 Key: FLINK-1293
>                 URL: https://issues.apache.org/jira/browse/FLINK-1293
>             Project: Flink
>          Issue Type: Improvement
>          Components: Java API, Scala API
>    Affects Versions: 0.7.0-incubating
>            Reporter: Viktor Rosenfeld
>            Assignee: Viktor Rosenfeld
>            Priority: Minor
>
> Currently, the output of an aggregation is of the same type as the input. This restriction
has to major drawbacks:
> 1. Every tuple field can only be used in one aggregation because the aggregations result
is stored in the field.
> 2. Aggregations having a return type that is different from the input type, e.g., count
or average, cannot be implemented.
> It would be nice to have the aggregation return any kind of tuple as a result, so the
restrictions above no longer apply.
> See also:
> - https://github.com/stratosphere/stratosphere/wiki/Design-of-Aggregate-Operator
> - http://apache-flink-incubator-mailing-list-archive.1008284.n3.nabble.com/Hi-Aggregation-support-td2311.html



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