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https://issues.apache.org/jira/browse/FLINK-3435?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15163494#comment-15163494
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ASF GitHub Bot commented on FLINK-3435:
---------------------------------------
Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/flink/pull/1699#discussion_r53985747
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/functions/IngestionTimeExtractor.java
---
@@ -0,0 +1,40 @@
+/*
+ * 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.streaming.api.functions;
+
+import org.apache.flink.streaming.api.watermark.Watermark;
+
+/**
+ * A timestamp assigner that assigns ingestion time timestamps.
+ *
+ * @param <T> The elements that get timestamps assigned.
+ */
+public class IngestionTimeExtractor<T> implements
AssignerWithPeriodicWatermarks<T> {
--- End diff --
That is true. My intuition was that it would be used to generate ingestion
time semantics, and that name makes it easy for users to figure this out.
> Change interplay of Ingestion Time and Event Time
> -------------------------------------------------
>
> Key: FLINK-3435
> URL: https://issues.apache.org/jira/browse/FLINK-3435
> Project: Flink
> Issue Type: Improvement
> Components: Streaming
> Affects Versions: 0.10.2
> Reporter: Stephan Ewen
> Assignee: Stephan Ewen
> Priority: Blocker
> Fix For: 1.0.0
>
>
> Currently, "EventTime" and "IngestionTime" are completely the same.
> For both happens the following:
> - Sources generate ingestion time timestamps and watermarks
> - If a user adds a manual timestamp extractor / watermark generator, then
> those override the ingestion time timestamps and watermarks
> - That implies that event time on a certain input falls back to ingestion
> time, if one forgets (or incorrectly uses) the timestamp extractors
> - Also, Ingestion Time and Event Time simply mix if some inputs have
> timestamp assigners, and others have not.
> This behavior is quite tricky to understand. After some discussions with
> [~aljoscha] and [~rmetzger], we suggest to change it the following way.
> 1. On Ingestion Time, the timestamps and watermarks are generated as they
> are now.
> 2. On event time, no default timestamps and watermarks are generated. If a
> user does not implement a timestamp extractor / watermark generator, then the
> event time operations will fail fast.
> 3. If one wants to use ingestion time on event time settings (mix), one can
> use an explicit "WallClockTimetampsAndWatermark" generator.
> 4. Later, the "Ingestion Time" settings should automatically disable and
> user-defined timestamp extractors / assigners.
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