pnowojski 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_r262126111
########## 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: > it is said: `aggregate functions ignore null values` Can you point me where did you get this? Is this part of SQL standard? `COUNT` function definitely doesn't ignore null values, so I would assume we should be able to define custom aggregate functions that work in a similar fashion. [This seems to support this]( https://modern-sql.com/concept/null#aggregates): > Most aggregate functions that return structured data (array_agg, json_objectagg, xmlagg) do not remove null values. > ... > For array_agg, it is even explicitly mentioned in SQL:2016-2: ยง10.9, General Rule 12gii, note 510. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
