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https://issues.apache.org/jira/browse/FLINK-7548?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16207782#comment-16207782
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Xingcan Cui commented on FLINK-7548:
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Hi [~fhueske], sorry for the late reply. I'll first share some ideas that
struck me and then keep the focus on this issue.
# Now that the rowtime can be extracted by expressions, shall we consider
allowing more data types for the original fields? For instance, the users may
want to extract the timestamps from a {{String}} field or even from multiple
fields by a UDF.
# Since the stream API do not support multiple watermarks, maybe it's not
necessary to define a list of {{RowtimeAttributeDescriptor}}.
# Sometimes the processing time could be inapplicable, while the streams are
lack of timestamps. I think it would be convenient to provide an inner
mechanism, which can materialize the ingestion time as the rowtime.
# Using Table API Expression sounds like a good idea. However, I just wonder
whether it will make the DDL harder to implement.
Best, Xingcan
> Support watermark generation for TableSource
> --------------------------------------------
>
> Key: FLINK-7548
> URL: https://issues.apache.org/jira/browse/FLINK-7548
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Reporter: Jark Wu
> Assignee: Fabian Hueske
> Priority: Blocker
> Fix For: 1.4.0
>
>
> As discussed in FLINK-7446, currently the TableSource only support to define
> rowtime field, but not support to extract watermarks from the rowtime field.
> We can provide a new interface called {{DefinedWatermark}}, which has two
> methods {{getRowtimeAttribute}} (can only be an existing field) and
> {{getWatermarkGenerator}}. The {{DefinedRowtimeAttribute}} will be marked
> deprecated.
> How to support periodic and punctuated watermarks and support some built-in
> strategies needs further discussion.
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