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https://issues.apache.org/jira/browse/FLINK-5564?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15859039#comment-15859039
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Shaoxuan Wang edited comment on FLINK-5564 at 2/9/17 5:16 AM:
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Thanks [~fhueske],
Absolutely, I agree with you that it is better to separate the huge PR into
some ones. (merge 1,2,3 will lead to more than 3K lines change)
But I am afraid I did not completely get your suggested #1. Migrating the
existing Agg without changing runtime code will lead to all IntergrationTest
fail. One possible way is that I create new interface (say AggregateFunction)
and create a few Aggs which is implemented from new interface (say intAgg
extends AggregateFunction), and in step #1, I just add queryPlan tests, like
what we usually did in GroupWindowTest. Is this what you are suggesting.
was (Author: shaoxuanwang):
Thanks [~fhueske],
Obsoletely, I agree with you that it is better to separate the huge PR into
some ones. (merge 1,2,3 will lead to more than 3K lines change)
But I am afraid I did not completely get your suggested #1. Migrating the
existing Agg without changing runtime code will lead to all IntergrationTest
fail. One possible way is that I create new interface (say AggregateFunction)
and create a few Aggs which is implemented from new interface (say intAgg
extends AggregateFunction), and in step #1, I just add queryPlan tests, like
what we usually did in GroupWindowTest. Is this what you are suggesting.
> User Defined Aggregates
> -----------------------
>
> 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
>
> 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/19JXK8jLIi8IqV9yf7hOs_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
> implements an Aggregate. Seven functions are needed even for a simple Count
> aggregate.
> 2. Another limitation of current aggregate function is that it can only be
> applied on one single column. There are many scenarios which require the
> aggregate function taking multiple columns as the inputs.
> 3. “Retraction” is not considered and covered in the current Aggregate.
> 4. It might be very good to have a local/global aggregate query plan
> optimization, which is very promising to optimize UDAGG performance in some
> scenarios.
> Proposed Changes:
> 1. Implement an aggregate dataStream API (Done by
> [FLINK-5582|https://issues.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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