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https://issues.apache.org/jira/browse/FLINK-3849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15926145#comment-15926145
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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_r106123284
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/schema/TableSourceTable.scala
---
@@ -25,6 +25,7 @@ import org.apache.flink.table.sources.TableSource
/** Table which defines an external table via a [[TableSource]] */
class TableSourceTable[T](
val tableSource: TableSource[T],
+ val tableEnv: TableEnvironment,
--- End diff --
Do we really need this reference here? I think it is only needs to provide
the FunctionCatalog for translating RexNodes into Expressions for filter
pushdown. Isn't the catalog of built-in functions sufficient for that (which is
available as a static object)? I don't think a TableSource would be able to
evaluate a predicate that includes a UDF, so the built-in functions should be
enough and we do not need to add the `TableEnvironment` here.
> 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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