wuchong commented on a change in pull request #9994: [FLINK-14322][table-api] Add watermark information in TableSchema URL: https://github.com/apache/flink/pull/9994#discussion_r341512739
########## File path: flink-table/flink-table-common/src/main/java/org/apache/flink/table/api/WatermarkSpec.java ########## @@ -0,0 +1,88 @@ +/* + * 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.api; + +import org.apache.flink.table.types.DataType; + +import java.util.Objects; + +import static org.apache.flink.util.Preconditions.checkNotNull; + +/** + * Watermark metadata defined in {@link TableSchema}. It mainly contains two parts, + * 1) the rowtime attribute. + * 2) the watermark generation strategy. + */ +public class WatermarkSpec { + + private final String rowtimeAttribute; + + private final String watermarkExpressionString; + + private final DataType watermarkExprOutputType; + + public WatermarkSpec(String rowtimeAttribute, String watermarkExpressionString, DataType watermarkExprOutputType) { + this.rowtimeAttribute = checkNotNull(rowtimeAttribute); + this.watermarkExpressionString = checkNotNull(watermarkExpressionString); + this.watermarkExprOutputType = checkNotNull(watermarkExprOutputType); + } + + /** + * Returns the name of rowtime attribute, it can be a nested field using dot separator. + * The referenced attribute must be present in the {@link TableSchema} and of + * type {@link org.apache.flink.table.types.logical.LogicalTypeRoot#TIMESTAMP_WITHOUT_TIME_ZONE}. + */ + public String getRowtimeAttribute() { + return rowtimeAttribute; + } + + /** + * Returns the string representation of watermark generation expression. + * The string representation is a qualified SQL expression string (UDFs are expanded). + */ + public String getWatermarkExpressionString() { + return watermarkExpressionString; Review comment: A `String` in the method name explicitly declares that the return value is a string representation instead of `Expression`. ---------------------------------------------------------------- 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: [email protected] With regards, Apache Git Services
