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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-5653) Add processing time OVER ROWS BETWEEN x PRECEDING aggregation to SQL
Date Thu, 02 Mar 2017 07:37:45 GMT

    [ https://issues.apache.org/jira/browse/FLINK-5653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15891752#comment-15891752
] 

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/3443#discussion_r103865652
  
    --- Diff: flink-libraries/flink-table/src/main/java/org/apache/flink/table/plan/logical/rel/util/WindowAggregateUtil.java
---
    @@ -0,0 +1,103 @@
    +/*
    + * 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.plan.logical.rel.util;
    +
    +import java.io.Serializable;
    +import java.util.List;
    +
    +import org.apache.calcite.rel.core.Window.Group;
    +import org.apache.calcite.rel.logical.LogicalWindow;
    +import org.apache.calcite.rex.RexLiteral;
    +
    +import com.google.common.collect.ImmutableList;
    +
    +public class WindowAggregateUtil implements Serializable {
    +
    +	private static final long serialVersionUID = -3916551736243544540L;
    +
    +	private LogicalWindow windowPointer = null;
    +
    +	public WindowAggregateUtil() {
    +
    +	}
    +
    +	public WindowAggregateUtil(LogicalWindow window) {
    +		this.windowPointer = window;
    +
    +	}
    +
    +	/**
    +	 * A utility function that checks whether a window is partitioned or it is a
    +	 * global window.
    +	 * 
    +	 * @param LogicalWindow
    +	 *            window to be checked for partitions
    +	 * @return true if partition keys are defined, false otherwise.
    +	 */
    +	public boolean isStreamPartitioned(LogicalWindow window) {
    +		// if it exists a group bounded by keys, the it is
    +		// a partitioned window
    +		for (Group group : window.groups) {
    +			if (!group.keys.isEmpty()) {
    +				return true;
    +			}
    +		}
    +
    +		return false;
    +	}
    +
    +	public int[] getKeysAsArray(Group group) {
    +		if (group == null) {
    +			return null;
    +		}
    +		return group.keys.toArray();
    +	}
    +
    +	/**
    +	 * This method returns the [[int]] lowerbound of a window when expressed
    +	 * with an integer e.g. ... ROWS BETWEEN [[value]] PRECEDING AND CURRENT ROW
    +	 * 
    +	 * @param constants
    +	 *            the list of constant to get the offset value
    +	 * @return return the value of the lowerbound if available -1 otherwise
    +	 */
    +
    +	public int getLowerBoundary(ImmutableList<RexLiteral> constants) {
    +		return ((Long)constants.get(0).getValue2()).intValue();
    --- End diff --
    
    Thank you very much. I was indeed puzzled by this. I will fix it according to your suggestion.
I even tried to get to the Calcite mailing list, but nothing like this came out. 


> 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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