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ASF GitHub Bot commented on FLINK-6334: --------------------------------------- Github user fhueske commented on a diff in the pull request: https://github.com/apache/flink/pull/3791#discussion_r114590134 --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala --- @@ -93,6 +103,11 @@ class Table( * }}} */ def select(fields: Expression*): Table = { + if (UserDefinedFunctionUtils.verifyTableFunctionCallExistence(this)) { --- End diff -- I think we can add these checks without touching all methods of `Table`. We could implement a method that recursively traverses a `LogicalNode` and checks if one of this children is an unbounded table function call. This check is performed in the constructor of Table and throws an exception except, the `logicalNode` itself is a `LogicalTableFunctionCall` (this is the case if it was created with the new constructor or `as()` was applied on it. That way we can remove all checks in the methods. > Refactoring UDTF interface > -------------------------- > > Key: FLINK-6334 > URL: https://issues.apache.org/jira/browse/FLINK-6334 > Project: Flink > Issue Type: Improvement > Components: Table API & SQL > Reporter: Ruidong Li > Assignee: Ruidong Li > Priority: Blocker > Fix For: 1.3.0 > > > The current UDTF leverages the table.join(expression) interface, which is not > a proper interface in terms of semantics. We would like to refactor this to > let UDTF use table.join(table) interface. Very briefly, UDTF's apply method > will return a Table Type, so Join(UDTF('a, 'b, ...) as 'c) shall be viewed as > join(Table) -- This message was sent by Atlassian JIRA (v6.3.15#6346)