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Date: Thu, 12 Oct 2017 12:32:00 +0000 (UTC)
From: "Fabian Hueske (JIRA)" <jira@apache.org>
To: issues@flink.apache.org
Message-ID: <JIRA.13035976.1484768856000.39821.1507811520743@Atlassian.JIRA>
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Subject: [jira] [Closed] (FLINK-5564) Add User Defined Aggregates in Table
 API
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archived-at: Thu, 12 Oct 2017 12:43:07 -0000


     [ https://issues.apache.org/jira/browse/FLINK-5564?page=3Dcom.atlassia=
n.jira.plugin.system.issuetabpanels:all-tabpanel ]

Fabian Hueske closed FLINK-5564.
--------------------------------
       Resolution: Implemented
    Fix Version/s: 1.3.0

UDAGGs were added with Flink 1.3.0

> Add User Defined Aggregates in Table API
> ----------------------------------------
>
>                 Key: FLINK-5564
>                 URL: https://issues.apache.org/jira/browse/FLINK-5564
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>            Reporter: Shaoxuan Wang
>            Assignee: Shaoxuan Wang
>            Priority: Critical
>             Fix For: 1.4.0, 1.3.0
>
>
> User-defined aggregates would be a great addition to the Table API / SQL.
> The current aggregate interface is not well suited for the external users=
.  This issue proposes to redesign the aggregate such that we can expose an=
 better external UDAGG interface to the users. The detailed design proposal=
 can be found here: https://docs.google.com/document/d/19JXK8jLIi8IqV9yf7hO=
s_Oz67yXOypY7Uh5gIOK2r-U/edit
> Motivation:
> 1. The current aggregate interface is not very concise to the users. One =
needs to know the design details of the intermediate Row buffer before impl=
ements an Aggregate. Seven functions are needed even for a simple Count agg=
regate.
> 2. Another limitation of current aggregate function is that it can only b=
e applied on one single column. There are many scenarios which require the =
aggregate function taking multiple columns as the inputs.
> 3. =E2=80=9CRetraction=E2=80=9D is not considered and covered in the curr=
ent Aggregate.
> 4. It might be very good to have a local/global aggregate query plan opti=
mization, which is very promising to optimize UDAGG performance in some sce=
narios.
> Proposed Changes:
> 1. Implement an aggregate dataStream API (Done by [FLINK-5582|https://iss=
ues.apache.org/jira/browse/FLINK-5582])
> 2. Update all the existing aggregates to use the new aggregate dataStream=
 API
> 3. Provide a better User-Defined Aggregate interface
> 4. Add retraction support
> 5. Add local/global aggregate


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