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https://issues.apache.org/jira/browse/FLINK-3849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15926147#comment-15926147
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ASF GitHub Bot commented on FLINK-3849:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3520#discussion_r106140096
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/sources/ProjectableTableSource.scala
---
@@ -24,7 +24,7 @@ package org.apache.flink.table.sources
*
* @tparam T The return type of the [[ProjectableTableSource]].
*/
-trait ProjectableTableSource[T] {
+trait ProjectableTableSource[T] extends TableSource[T] {
--- End diff --
Why is this change necessary? A `ProjectableTableSource` always needs to
implement either `BatchTableSource` or `StreamTableSource` (or both) which
already implement `TableSource`.
> 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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