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ASF GitHub Bot commented on FLINK-4856: --------------------------------------- Github user aljoscha commented on a diff in the pull request: https://github.com/apache/flink/pull/3336#discussion_r101750130 --- Diff: flink-core/src/main/java/org/apache/flink/api/common/typeutils/base/MapSerializer.java --- @@ -0,0 +1,179 @@ +/* + * 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.common.typeutils.base; + +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.core.memory.DataInputView; +import org.apache.flink.core.memory.DataOutputView; +import org.apache.flink.util.Preconditions; + +import java.io.IOException; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + +/** + * A serializer for {@link List Lists}. The serializer relies on an element serializer --- End diff -- Wrong Javadoc > Add MapState for keyed streams > ------------------------------ > > Key: FLINK-4856 > URL: https://issues.apache.org/jira/browse/FLINK-4856 > Project: Flink > Issue Type: New Feature > Components: DataStream API, State Backends, Checkpointing > Reporter: Xiaogang Shi > Assignee: Xiaogang Shi > > Many states in keyed streams are organized as key-value pairs. Currently, > these states are implemented by storing the entire map into a ValueState or a > ListState. The implementation however is very costly because all entries have > to be serialized/deserialized when updating a single entry. To improve the > efficiency of these states, MapStates are urgently needed. -- This message was sent by Atlassian JIRA (v6.3.15#6346)