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https://issues.apache.org/jira/browse/FLINK-6196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15960726#comment-15960726
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ASF GitHub Bot commented on FLINK-6196:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3623#discussion_r110381407
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/schema/DeferredTypeFlinkTableFunction.scala
---
@@ -40,6 +43,10 @@ class DeferredTypeFlinkTableFunction(
val implicitResultType: TypeInformation[_])
extends FlinkTableFunction(tableFunction, evalMethod) {
+ val paramTypeInfos = evalMethod.getParameterTypes.map { paramType =>
+ TypeExtractor.getForClass(paramType)
--- End diff --
I noticed that the semantics of how the type lists are obtained are a bit
different in both cases. In `UserDefinedFunctionUtils` we look at the
parameters that are handed to the function. Here we look at the signature of
the `eval` method. The result will be different if the `eval` method is called
with more specific types than its signature has, e.g., if we have `eval(Object
o1, Object o2)` and call it with `eval(new Integer(1), new String("Hello"))`.
Both approaches make sense:
1. parameter types are more specific
2. with signature types it is easier to identify which eval() method is
called.
What do you think @clarkyzl, @KurtYoung?
> Support dynamic schema in Table Function
> ----------------------------------------
>
> Key: FLINK-6196
> URL: https://issues.apache.org/jira/browse/FLINK-6196
> Project: Flink
> Issue Type: Improvement
> Components: Table API & SQL
> Reporter: Zhuoluo Yang
> Assignee: Zhuoluo Yang
>
> In many of our use cases. We have to decide the schema of a UDTF at the run
> time. For example. udtf('c1, c2, c3') will generate three columns for a
> lateral view.
> Most systems such as calcite and hive support this feature. However, the
> current implementation of flink didn't implement the feature correctly.
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