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From walterddr <...@git.apache.org>
Subject [GitHub] flink pull request #5555: [FLINK-8689][table]Add runtime support of distinct...
Date Mon, 26 Feb 2018 14:22:04 GMT
Github user walterddr commented on a diff in the pull request:

    https://github.com/apache/flink/pull/5555#discussion_r170603205
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/aggfunctions/DistinctAggDelegateFunction.scala
---
    @@ -0,0 +1,122 @@
    +/*
    + * 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.table.functions.aggfunctions
    +
    +import java.util
    +
    +import org.apache.flink.api.common.typeinfo.{BasicTypeInfo, TypeInformation}
    +import org.apache.flink.api.java.typeutils.{PojoField, PojoTypeInfo}
    +import org.apache.flink.table.api.dataview.MapView
    +import org.apache.flink.table.dataview.MapViewTypeInfo
    +import org.apache.flink.table.functions.AggregateFunction
    +
    +class DistinctAccumulator[E, ACC] (var mapView: MapView[E, Integer], var realAcc: ACC)
{
    +  def this() {
    +    this(null, null.asInstanceOf[ACC])
    +  }
    +
    +  def getRealAcc: ACC = realAcc
    +
    +  def canEqual(a: Any): Boolean = a.isInstanceOf[DistinctAccumulator[E, ACC]]
    +
    +  override def equals(that: Any): Boolean =
    +    that match {
    +      case that: DistinctAccumulator[E, ACC] => that.canEqual(this) &&
    +        this.mapView == that.mapView
    +      case _ => false
    +    }
    +
    +}
    +
    +class DistinctAggDelegateFunction[E, ACC](elementTypeInfo: TypeInformation[_],
    +                                          var realAgg: AggregateFunction[_, ACC])
    +  extends AggregateFunction[util.Map[E, Integer], DistinctAccumulator[E, ACC]] {
    +
    +  def getRealAgg: AggregateFunction[_, ACC] = realAgg
    +
    +  override def createAccumulator(): DistinctAccumulator[E, ACC] = {
    +    new DistinctAccumulator[E, ACC](
    +      new MapView[E, Integer](
    +        elementTypeInfo.asInstanceOf[TypeInformation[E]],
    +        BasicTypeInfo.INT_TYPE_INFO),
    +      realAgg.createAccumulator())
    +  }
    +
    +  def accumulate(acc: DistinctAccumulator[E, ACC], element: E): Boolean = {
    +    if (element != null) {
    +      if (acc.mapView.contains(element)) {
    +        acc.mapView.put(element, acc.mapView.get(element) + 1)
    +        false
    +      } else {
    +        acc.mapView.put(element, 1)
    +        true
    +      }
    +    } else {
    +      false
    +    }
    +  }
    +
    +  def accumulate(acc: DistinctAccumulator[E, ACC], element: E, count: Int): Boolean =
{
    +    if (element != null) {
    +      if (acc.mapView.contains(element)) {
    +        acc.mapView.put(element, acc.mapView.get(element) + count)
    +        false
    +      } else {
    +        acc.mapView.put(element, count)
    +        true
    +      }
    +    } else {
    +      false
    +    }
    +  }
    +
    +  def retract(acc: DistinctAccumulator[E, ACC], element: E): Boolean = {
    +    if (element != null) {
    +      val count = acc.mapView.get(element)
    +      if (count == 1) {
    +        acc.mapView.remove(element)
    +        true
    +      } else {
    +        acc.mapView.put(element, count - 1)
    +        false
    +      }
    +    } else {
    +      false
    +    }
    +  }
    +
    +  def resetAccumulator(acc: DistinctAccumulator[E, ACC]): Unit = {
    +    acc.mapView.clear()
    +  }
    +
    +  override def getValue(acc: DistinctAccumulator[E, ACC]): util.Map[E, Integer] = {
    +    acc.mapView.map
    +  }
    +
    +  override def getAccumulatorType: TypeInformation[DistinctAccumulator[E, ACC]] = {
    +    val clazz = classOf[DistinctAccumulator[E, ACC]]
    +    val pojoFields = new util.ArrayList[PojoField]
    +    pojoFields.add(new PojoField(clazz.getDeclaredField("mapView"),
    +      new MapViewTypeInfo[E, Integer](
    +        elementTypeInfo.asInstanceOf[TypeInformation[E]], BasicTypeInfo.INT_TYPE_INFO)))
    +    pojoFields.add(new PojoField(clazz.getDeclaredField("realAcc"),
    +      realAgg.getAccumulatorType))
    +    new PojoTypeInfo[DistinctAccumulator[E, ACC]](clazz, pojoFields)
    --- End diff --
    
    Yes, I was actually aware of that as one of the limitation of the `DataView` API and will
propose a change in another PR. At this point since this is solely used for distinct aggregation.
I think explicitly catch and thrown and exception if `realAcc` contains Pojo type? 


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