[jira] [Updated] (FLINK-18558) Introduce collect iterator with at least once semantics and exactly once semantics without fault tolerance

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-18558?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ASF GitHub Bot updated FLINK-18558:
-----------------------------------
    Labels: pull-request-available  (was: )

> Introduce collect iterator with at least once semantics and exactly once semantics without fault tolerance
> ----------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-18558
>                 URL: https://issues.apache.org/jira/browse/FLINK-18558
>             Project: Flink
>          Issue Type: Improvement
>          Components: API / DataStream, Table SQL / API
>            Reporter: Caizhi Weng
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.12.0
>
>
> Currently {{TableResult#collect}} and {{DataStreamUtils#collect}} can only produce results if users explicitly enable checkpoint for infinite streaming jobs. It would be strange to require the users to do so if they just want to take a look at their data.
> We should introduce collect iterator with at least once semantics and exactly once semantics without fault tolerance. When calling the {{collect}} method, we should automatically pick an iterator for the user:
> * If the user does not explicitly enable a checkpoint, we use exactly once iterator without fault tolerance. That is to say, the iterator will throw exception once the job restarts.
> * If the user explicitly enables an exactly once checkpoint, we use the current implementation of collect iterator.
> * If the user explicitly enables an at least once checkpoint, we use the at least once iterator. That is to say, the iterator ignores both checkpoint information and job restarts.



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