xccui commented on a change in pull request #6407: [FLINK-9877][docs] Add documentation page for different datastream joins URL: https://github.com/apache/flink/pull/6407#discussion_r205176853
########## File path: docs/dev/stream/operators/joining.md ########## @@ -0,0 +1,286 @@ +--- +title: "Joining" +nav-id: streaming_joins +nav-show_overview: true +nav-parent_id: streaming +nav-pos: 10 +--- +<!-- +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. +--> + +* toc +{:toc} + +# Window Join +A window join will join the elements of two streams that share a common key and lie in the same window. These windows can be defined by using a [window assigner]({{ site.baseurl}}/dev/stream/operators/windows.html#window-assigners) and are evaluated on a union of both streams. This is especially important for session window joins, which will be demonstrated below. + +The joined elements are then passed to a user-defined `JoinFunction` or `FlatJoinFunction` where the user can perform transformations on the joined elements. Review comment: The elements from both sides are then passed to a user-defined `JoinFunction` or `FlatJoinFunction` where users can **emit results that meet the join criteria**. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
