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https://issues.apache.org/jira/browse/FLINK-6334?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15991536#comment-15991536
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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_r114061878
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala
---
@@ -309,6 +308,42 @@ class Table(
}
/**
+ * Joins this [[Table]] to a user-defined
[[org.apache.calcite.schema.TableFunction]]. Similar
+ * to an SQL left outer join with ON TRUE, but it works with a table
function. It returns all
--- End diff --
I think the description of the outer join is confusing.
In the sentence "... all the rows from the outer table (table on the left
of the operator), and rows that do not match the condition from the table
function"
1. it should be "that do match the condition"
2. there is no condition
3. it reads as the rows of the left side and table function would be
unioned.
I think we can assume that the user knows how a left join works. We should
simply say that the each row of the outer table is joined with each row
produced by the table function call and that the outer row is padded with nulls
if the table function returns an empty table.
> 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
>
> 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)
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