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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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Ingo Bürk reassigned FLINK-23917:
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Assignee: Ingo Bürk
> 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
>
> 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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