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https://issues.apache.org/jira/browse/FLINK-3754?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15280165#comment-15280165
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ASF GitHub Bot commented on FLINK-3754:
---------------------------------------
Github user yjshen commented on a diff in the pull request:
https://github.com/apache/flink/pull/1958#discussion_r62853599
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/scala/table/expressionDsl.scala
---
@@ -130,19 +130,17 @@ trait ImplicitExpressionOperations {
* @param endIndex last character of the substring (starting at 1,
inclusive)
* @return substring
*/
- def substring(beginIndex: Expression, endIndex: Expression) = {
- Call(BuiltInFunctionNames.SUBSTRING, expr, beginIndex, endIndex)
- }
+ def substring(beginIndex: Expression, endIndex: Expression) =
+ SubString(expr, beginIndex, endIndex)
/**
* Creates a substring of the given string beginning at the given index
to the end.
*
* @param beginIndex first character of the substring (starting at 1,
inclusive)
* @return substring
*/
- def substring(beginIndex: Expression) = {
- Call(BuiltInFunctionNames.SUBSTRING, expr, beginIndex)
- }
+ def substring(beginIndex: Expression) =
+ new SubString(expr, beginIndex)
--- End diff --
Since `SubString` is defined as `case class SubString(str: Expression,
begin: Expression, end: Expression)` and so does the generated `apply` method,
the `new` here cannot be removed, otherwise complaining of `cannot resolve
subString with such signature`
> Add a validation phase before construct RelNode using TableAPI
> --------------------------------------------------------------
>
> Key: FLINK-3754
> URL: https://issues.apache.org/jira/browse/FLINK-3754
> Project: Flink
> Issue Type: Improvement
> Components: Table API
> Affects Versions: 1.0.0
> Reporter: Yijie Shen
> Assignee: Yijie Shen
>
> Unlike sql string's execution, which have a separate validation phase before
> RelNode construction, Table API lacks the counterparts and the validation is
> scattered in many places.
> I suggest to add a single validation phase and detect problems as early as
> possible.
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