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https://issues.apache.org/jira/browse/FLINK-7548?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16174581#comment-16174581
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Fabian Hueske commented on FLINK-7548:
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Thanks for the feedback [~jark]!
bq. Regarding to the existing field type, should we support Timestamp type?
Timestamp is a very common type in traditional database.
You mean to support {{TIMESTAMP}} in addition to {{LONG}} as existing timestamp
column? I think that's a good idea. I will address that in FLINK-7446.
bq. What about to make TableSource support "Computed Column" instead of UDF
converter?
Initially, I was also thinking about arbitrary expressions for column
conversions. The "problem" would be that {{TableSource}} (and the
{{DefinedRowtimeAttribute}} interface) are shared among Table API and SQL, but
Table API and SQL expressions are different.
The easiest would be to use the Table API expression parser but this would be
inconsistent with SQL. I proposed using a UDF because this would avoid the
problem at the cost of implementing a UDF for each conversion. I'm definitely
open for suggestions here.
bq. I agree to preserve the type.
Yes, I totally see that. I'd solve this in a follow up issue because I think
we'd need a different time indicator type for that and some changes would be
more involved.
> 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
>
> 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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