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https://issues.apache.org/jira/browse/FLINK-14807?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17046376#comment-17046376
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Jiangjie Qin commented on FLINK-14807:
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{quote}Your first point is actually the root of complexity. According to
current analysis, JM should be the one who is responsible to retrieve the
results, this would make things more complex and not straightforward, e.g.
lacking of communication channel between tasks and JM.
{quote}
The communication channel is always needed whether it is exactly once or not.
Exactly once semantic (EOS) requires additional protocol on top of the basic
communication channel. When I say it is simpler, I meant the protocol would be
simpler.
One straightforward implementation will be letting JM act like a proxy and just
forward the request from client to the sinks in a round robin manner with lazy
acks. In this case EOS is much easier given that we can assume the client is
always up and fetching.
> Add Table#collect api for fetching data to client
> -------------------------------------------------
>
> Key: FLINK-14807
> URL: https://issues.apache.org/jira/browse/FLINK-14807
> Project: Flink
> Issue Type: New Feature
> Components: Table SQL / API
> Affects Versions: 1.9.1
> Reporter: Jeff Zhang
> Priority: Major
> Labels: usability
> Fix For: 1.11.0
>
> Attachments: table-collect.png
>
>
> Currently, it is very unconvinient for user to fetch data of flink job unless
> specify sink expclitly and then fetch data from this sink via its api (e.g.
> write to hdfs sink, then read data from hdfs). However, most of time user
> just want to get the data and do whatever processing he want. So it is very
> necessary for flink to provide api Table#collect for this purpose.
>
> Other apis such as Table#head, Table#print is also helpful.
>
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