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https://issues.apache.org/jira/browse/FLINK-3849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15927919#comment-15927919
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ASF GitHub Bot commented on FLINK-3849:
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Github user KurtYoung commented on the issue:
https://github.com/apache/flink/pull/3520
Hi @fhueske, you just pointed out a question i had when tonycox
implementing the first version. Why we are preventing `FilterableTableSource`
from modifying the expressions? I think it's totally up to them whether
changing the expressions they took or keep them just they were. We have not
reason to restrict the `FilterableTableSource`'s behavior if they just do the
things right.
Pass in a java list and told user who extending this to pick and remove the
expressions the support is not super nice. But even if user just pick
expressions but not remove them, we still get the correct answer.
What do you think?
> Add FilterableTableSource interface and translation rule
> --------------------------------------------------------
>
> Key: FLINK-3849
> URL: https://issues.apache.org/jira/browse/FLINK-3849
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: Fabian Hueske
> Assignee: Kurt Young
>
> Add a {{FilterableTableSource}} interface for {{TableSource}} implementations
> which support filter push-down.
> The interface could look as follows
> {code}
> def trait FilterableTableSource {
> // returns unsupported predicate expression
> def setPredicate(predicate: Expression): Expression
> }
> {code}
> In addition we need Calcite rules to push a predicate (or parts of it) into a
> TableScan that refers to a {{FilterableTableSource}}. We might need to tweak
> the cost model as well to push the optimizer in the right direction.
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