laraschmidt commented on a change in pull request #15275: URL: https://github.com/apache/beam/pull/15275#discussion_r683670918
########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/join/EventTimeEquiJoin.java ########## @@ -0,0 +1,272 @@ +/* + * 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.beam.sdk.transforms.join; + +import com.google.auto.value.AutoValue; +import org.apache.beam.sdk.coders.Coder; +import org.apache.beam.sdk.coders.KvCoder; +import org.apache.beam.sdk.state.OrderedListState; +import org.apache.beam.sdk.state.StateSpec; +import org.apache.beam.sdk.state.StateSpecs; +import org.apache.beam.sdk.state.TimeDomain; +import org.apache.beam.sdk.state.TimerMap; +import org.apache.beam.sdk.state.TimerSpec; +import org.apache.beam.sdk.state.TimerSpecs; +import org.apache.beam.sdk.transforms.DoFn; +import org.apache.beam.sdk.transforms.Flatten; +import org.apache.beam.sdk.transforms.PTransform; +import org.apache.beam.sdk.transforms.ParDo; +import org.apache.beam.sdk.values.KV; +import org.apache.beam.sdk.values.PCollection; +import org.apache.beam.sdk.values.PCollectionList; +import org.apache.beam.sdk.values.TimestampedValue; +import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.ImmutableList; +import org.joda.time.Duration; +import org.joda.time.Instant; + +/** + * Returns a {@link PTransform} that performs a {@link EventTimeEquiJoin} on two PCollections. A + * {@link EventTimeEquiJoin} joins elements with equal keys bounded by the difference in event time. + * + * <p>Example of performing a {@link EventTimeEquiJoin}: + * + * <pre>{@code + * PCollection<KV<K, V1>> pt1 = ...; + * PCollection<KV<K, V2>> pt2 = ...; + * + * PCollection<KV<K, Pair<V1, V2>> eventTimeEquiJoinCollection = + * pt1.apply(EventTimeEquiJoin.<K, V1, V2>of(pt2)); + * + * @param secondCollection the second collection to use in the join. + * @param <K> the type of the keys in the input {@code PCollection}s + * @param <V1> the type of the value in the first {@code PCollection} + * @param <V2> the type of the value in the second {@code PCollection} + * </pre> + */ +@AutoValue +public abstract class EventTimeEquiJoin<K, V1, V2> Review comment: I looked up what Flink and Spark call them. Spark doesn't really have a name. Flink's joins seem to be different (processing on a table at a point of time instead of things being equivalent). Tyson's suggestion in the doc was EventTimeBoundedEquiJoin. Not sure I have any other suggestions. Maybe we could shorten it and move some to the function: E.g. EventTimeBoundedJoin.innerEquiOf() or something like that? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
