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https://issues.apache.org/jira/browse/FLINK-3849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15926143#comment-15926143
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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_r105726756
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/sources/TableSource.scala
---
@@ -39,4 +39,6 @@ trait TableSource[T] {
/** Returns the [[TypeInformation]] for the return type of the
[[TableSource]]. */
def getReturnType: TypeInformation[T]
+ /** Describes the table source */
+ def explainTerms(pw: RelWriter): RelWriter = pw
--- End diff --
Do we need this method? So far we tried to keep Calcite out of the
TableSource interface. Can we change this to `explainSource(): String` and set
the String in `BatchTableSourceScan` and `StreamTableSourceScan`?
> 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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