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ASF GitHub Bot commented on FLINK-4691: --------------------------------------- Github user twalthr commented on a diff in the pull request: https://github.com/apache/flink/pull/2562#discussion_r82993938 --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/runtime/aggregate/PropertyRead.scala --- @@ -0,0 +1,33 @@ +/* + * 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.table.runtime.aggregate + +import org.apache.flink.streaming.api.windowing.windows.Window + +/** + * Base class for reading a window property. The property will be extracted once and + * can be read multiple times. + */ +trait PropertyRead[T] extends Serializable { + + def extract(window: Window): Unit --- End diff -- In general I agree to your solution, but right now we support to have the same operation multiple times in a query. E.g. ``` .window(Session withGap 3.milli on 'rowtime as 'w) .select('string, 'w.end, 'w.end) ``` Your code would fail. Let's leave the aggregation as it is for now and rework it again later. The aggregations have to be reworked anyway for efficiency. > Add group-windows for streaming tables > --------------------------------------- > > Key: FLINK-4691 > URL: https://issues.apache.org/jira/browse/FLINK-4691 > Project: Flink > Issue Type: Sub-task > Components: Table API & SQL > Reporter: Timo Walther > Assignee: Timo Walther > > Add Tumble, Slide, Session group-windows for streaming tables as described in > [FLIP-11|https://cwiki.apache.org/confluence/display/FLINK/FLIP-11%3A+Table+API+Stream+Aggregations]. > > Implementation of group-windows on streaming tables. This includes > implementing the API of group-windows, the logical validation for > group-windows, and the definition of the “rowtime” and “systemtime” keywords. > Group-windows on batch tables won’t be initially supported and will throw an > exception. -- This message was sent by Atlassian JIRA (v6.3.4#6332)