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https://issues.apache.org/jira/browse/FLINK-6216?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15949927#comment-15949927
 ] 

ASF GitHub Bot commented on FLINK-6216:
---------------------------------------

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/3646#discussion_r109045587
  
    --- Diff: 
flink-libraries/flink-table/src/test/scala/org/apache/flink/table/api/scala/stream/table/GroupAggregationsITCase.scala
 ---
    @@ -0,0 +1,304 @@
    +/*
    + * 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.scala.stream.table
    +
    +import org.apache.flink.api.common.typeinfo.BasicTypeInfo
    +import org.apache.flink.api.scala._
    +import org.apache.flink.streaming.api.scala.StreamExecutionEnvironment
    +import org.apache.flink.streaming.util.StreamingMultipleProgramsTestBase
    +import org.apache.flink.table.api.scala._
    +import org.apache.flink.table.api.scala.stream.utils.{StreamITCase, 
StreamTestData}
    +import org.apache.flink.table.api.{TableEnvironment, ValidationException}
    +import org.apache.flink.types.Row
    +import org.junit.Assert.assertEquals
    +import org.junit.Test
    +
    +import scala.collection.mutable
    +
    +/**
    +  * Tests of groupby (without window & early-firing) aggregations
    +  */
    +class GroupAggregationsITCase extends StreamingMultipleProgramsTestBase {
    +
    +  @Test(expected = classOf[ValidationException])
    +  def testGroupingOnNonExistentField(): Unit = {
    --- End diff --
    
    These syntax tests should be moved to a `GroupAggregationsTest` class that 
also tests a few execution plans (like `GroupWindowTest`).


> DataStream unbounded groupby aggregate with early firing
> --------------------------------------------------------
>
>                 Key: FLINK-6216
>                 URL: https://issues.apache.org/jira/browse/FLINK-6216
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table API & SQL
>            Reporter: Shaoxuan Wang
>            Assignee: Shaoxuan Wang
>
> Groupby aggregate results in a replace table. For infinite groupby aggregate, 
> we need a mechanism to define when the data should be emitted (early-fired). 
> This task is aimed to implement the initial version of unbounded groupby 
> aggregate, where we update and emit aggregate value per each arrived record. 
> In the future, we will implement the mechanism and interface to let user 
> define the frequency/period of early-firing the unbounded groupby aggregation 
> results.
> The limit space of backend state is one of major obstacles for supporting 
> unbounded groupby aggregate in practical. Due to this reason, we suggest two 
> common (and very useful) use-cases of this unbounded groupby aggregate:
> 1. The range of grouping key is limit. In this case, a new arrival record 
> will either insert to state as new record or replace the existing record in 
> the backend state. The data in the backend state will not be evicted if the 
> resource is properly provisioned by the user, such that we can provision the 
> correctness on aggregation results.
> 2. When the grouping key is unlimited, we will not be able ensure the 100% 
> correctness of "unbounded groupby aggregate". In this case, we will reply on 
> the TTL mechanism of the RocksDB backend state to evicted old data such that 
> we can provision the correct results in a certain time range.



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