stevenzwu commented on code in PR #8553: URL: https://github.com/apache/iceberg/pull/8553#discussion_r1397721229
########## flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/reader/ColumnStatsWatermarkExtractor.java: ########## @@ -0,0 +1,72 @@ +/* + * 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.iceberg.flink.source.reader; + +import java.io.Serializable; +import java.util.Comparator; +import java.util.concurrent.TimeUnit; +import org.apache.flink.annotation.Internal; +import org.apache.iceberg.Schema; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; +import org.apache.iceberg.relocated.com.google.common.base.Preconditions; +import org.apache.iceberg.types.Conversions; +import org.apache.iceberg.types.Type.TypeID; +import org.apache.iceberg.types.Types; + +/** + * {@link SplitWatermarkExtractor} implementation which uses an Iceberg timestamp column statistics + * to get the watermarks for the {@link IcebergSourceSplit}. This watermark is emitted by the {@link + * WatermarkExtractorRecordEmitter} along with the actual records. + */ +@Internal +public class ColumnStatsWatermarkExtractor implements SplitWatermarkExtractor, Serializable { + private final int tsFieldId; + private final TimeUnit timeUnit; + + /** + * Creates the extractor. + * + * @param schema The schema of the Table + * @param tsFieldName The column which should be used as an event time + * @param timeUnit Used for converting the long value to epoch milliseconds + */ + public ColumnStatsWatermarkExtractor(Schema schema, String tsFieldName, TimeUnit timeUnit) { + Types.NestedField field = schema.findField(tsFieldName); + TypeID typeID = field.type().typeId(); + Preconditions.checkArgument( + typeID.equals(TypeID.LONG) || typeID.equals(TypeID.TIMESTAMP), + "Found %s, expected a LONG or TIMESTAMP column for watermark generation.", + typeID); + this.tsFieldId = field.fieldId(); + // Use the timeUnit only for Long columns. + this.timeUnit = typeID.equals(TypeID.LONG) ? timeUnit : TimeUnit.MICROSECONDS; Review Comment: > Since Flink does not have any restrictions for watermarks, other than it should be long, I think it is fine for us emitting watermark as we store it in Iceberg. that is not the case. here is the Flink doc: https://nightlies.apache.org/flink/flink-docs-release-1.18/docs/dev/datastream/event-time/generating_watermarks/ ``` Attention: Both timestamps and watermarks are specified as milliseconds since the Java epoch of 1970-01-01T00:00:00Z. ``` but it seems that we are doing the right thing and producing milli-seconds since epoch. -- 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. To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For additional commands, e-mail: issues-h...@iceberg.apache.org
