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https://issues.apache.org/jira/browse/FLINK-23917?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated FLINK-23917:
-----------------------------------
    Labels: pull-request-available  (was: )

> Project metadata columns to apply to sources which do not implement 
> projection pushdown
> ---------------------------------------------------------------------------------------
>
>                 Key: FLINK-23917
>                 URL: https://issues.apache.org/jira/browse/FLINK-23917
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / Planner
>            Reporter: Ingo Bürk
>            Assignee: Ingo Bürk
>            Priority: Major
>              Labels: pull-request-available
>
> If a source implements SupportsReadingMetadata, but not 
> SupportsProjectionPushDown, #applyReadableMetadata is always called with all 
> metadata keys declared in the table's schema. If SupportsProjectionPushDown 
> is implemented, this is filtered down to only the required metadata keys. 
> This can be a problem since metadata could be expensive to calculate.
> The root cause for this is that the projection happens in 
> PushProjectIntoTableSourceScanRule which doesn't run for sources which do not 
> implement projection pushdown. We should add a new separate rule which 
> projects required metadata keys for the source in this case.



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