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https://issues.apache.org/jira/browse/FLINK-7548?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16215805#comment-16215805
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Fabian Hueske commented on FLINK-7548:
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Thanks for the feedback [~wheat9].
I've addressed the issue of projection push down in my WIP branch and think
I've found a good solution.
A {{ProjectableTableSource}} only needs to adjust the {{TypeInformation}} and
the {{DataStream}} of {{DataSet}}. The {{TableSchema}} does not need to be
adapted. I've also extended the support for projection push down by pushing
projection into a table scan even if the {{TableSource}} does not implement
{{ProjectableTableSource}}. In that case, the projection is applied by the
initial {{Row}} conversion such that a projecting Calc can be removed if only
selects or reorders fields. It would also be possible to push expressions into
the scan, but that should be a follow up issue.
I'll open a PR in the next hours. It will be quite large (~2500 LOC changes)
but it would be great if I could get some feedback, especially for the API
facing classes.
> Support watermark generation for TableSource
> --------------------------------------------
>
> Key: FLINK-7548
> URL: https://issues.apache.org/jira/browse/FLINK-7548
> Project: Flink
> Issue Type: Improvement
> 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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