hequn8128 commented on a change in pull request #6787: [FLINK-8577][table] Implement proctime DataStream to Table upsert conversion URL: https://github.com/apache/flink/pull/6787#discussion_r253745265
########## File path: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/UpsertToRetractionProcessFunction.scala ########## @@ -0,0 +1,104 @@ +/* + * 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.runtime + +import org.apache.flink.api.common.state.{ValueState, ValueStateDescriptor} +import org.apache.flink.api.java.typeutils.RowTypeInfo +import org.apache.flink.configuration.Configuration +import org.apache.flink.streaming.api.functions.ProcessFunction +import org.apache.flink.table.api.StreamQueryConfig +import org.apache.flink.table.runtime.aggregate.ProcessFunctionWithCleanupState +import org.apache.flink.table.runtime.types.CRow +import org.apache.flink.table.util.Logging +import org.apache.flink.types.Row +import org.apache.flink.util.Collector + +/** + * Function used to convert upsert to retractions. + * + * @param rowTypeInfo the output row type info. + * @param queryConfig the configuration for the query. + */ +class UpsertToRetractionProcessFunction( Review comment: A good question! We can't use `LAST_VALUE` aggregate function here. An aggregate function ignores null input according to the SQL standard. Considering we have the following two inputs:`(key, value1, null)` and then `(key, null, value2)`, the result will be `(key, value1, value2)` if we use LAST_VALUE, while the result should be `(key, null, value2)`, i.e., the last row of the input. That's why I named the operator `LastRow` before. ---------------------------------------------------------------- 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: [email protected] With regards, Apache Git Services
