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https://issues.apache.org/jira/browse/FLINK-5653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15927699#comment-15927699
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ASF GitHub Bot commented on FLINK-5653:
---------------------------------------
Github user huawei-flink commented on a diff in the pull request:
https://github.com/apache/flink/pull/3547#discussion_r106366744
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/aggregate/BoundedProcessingOverWindowFunction.scala
---
@@ -0,0 +1,97 @@
+/*
+ * 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.aggregate
+
+import org.apache.flink.api.java.tuple.Tuple
+import org.apache.flink.types.Row
+import org.apache.flink.configuration.Configuration
+import
org.apache.flink.streaming.api.functions.windowing.RichWindowFunction
+import org.apache.flink.streaming.api.windowing.windows.Window
+import org.apache.flink.util.Collector
+import org.apache.flink.table.functions.AggregateFunction
+import org.apache.flink.api.java.typeutils.RowTypeInfo
+import org.apache.flink.util.Preconditions
+import org.apache.flink.table.functions.Accumulator
+import java.lang.Iterable
+
+class BoundedProcessingOverWindowFunction[W <: Window](
--- End diff --
Thanks a lot for the clarification. I am really willing to do it right, but
at the same time I need to understand. So, please be patient. :-)
When we started discussing the issue with @fhueske
(https://issues.apache.org/jira/browse/FLINK-5654?filter=-1) there was a
decision to use window, not process function.
Code consistency is pretty much the same, just extening a different
interface. I understand that ProcessFunction can manage its state, but window
checkpointing should replay all events in case of failure, so we would have
consistent processing even without managing this level of granularity in the
state. With procTime semantic, we can neglect retraction, and window can anyway
customize triggering function.
I don't understand the third point.
The main argument I see for this specific case is that ProcessFunction
supports granular state management. Besides the alleged code consistency.
> Add processing time OVER ROWS BETWEEN x PRECEDING aggregation to SQL
> --------------------------------------------------------------------
>
> Key: FLINK-5653
> URL: https://issues.apache.org/jira/browse/FLINK-5653
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Reporter: Fabian Hueske
> Assignee: Stefano Bortoli
>
> The goal of this issue is to add support for OVER ROWS aggregations on
> processing time streams to the SQL interface.
> Queries similar to the following should be supported:
> {code}
> SELECT
> a,
> SUM(b) OVER (PARTITION BY c ORDER BY procTime() ROWS BETWEEN 2 PRECEDING
> AND CURRENT ROW) AS sumB,
> MIN(b) OVER (PARTITION BY c ORDER BY procTime() ROWS BETWEEN 2 PRECEDING
> AND CURRENT ROW) AS minB
> FROM myStream
> {code}
> The following restrictions should initially apply:
> - All OVER clauses in the same SELECT clause must be exactly the same.
> - The PARTITION BY clause is optional (no partitioning results in single
> threaded execution).
> - The ORDER BY clause may only have procTime() as parameter. procTime() is a
> parameterless scalar function that just indicates processing time mode.
> - UNBOUNDED PRECEDING is not supported (see FLINK-5656)
> - FOLLOWING is not supported.
> The restrictions will be resolved in follow up issues. If we find that some
> of the restrictions are trivial to address, we can add the functionality in
> this issue as well.
> This issue includes:
> - Design of the DataStream operator to compute OVER ROW aggregates
> - Translation from Calcite's RelNode representation (LogicalProject with
> RexOver expression).
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