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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-5698) Add NestedFieldsProjectableTableSource interface
Date Tue, 07 Feb 2017 09:29:42 GMT

    [ https://issues.apache.org/jira/browse/FLINK-5698?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15855634#comment-15855634

ASF GitHub Bot commented on FLINK-5698:

Github user wuchong commented on the issue:

    Hi @tonycox , thanks for this PR. 
    It seems that you are using column names to represent the (nested) fields that are projected.
I'm afraid that it can't work when the composite columns have the same nested field name.
Such as a table schema `student<name, age>, teacher<name, age>`, and the projected
fields are `name, age`, we can't determine whether the `name` is `student.name` or `teacher.name`.
    IMO, we can use the full qualifier column names with `.` separator to represent the (nested)
fields. For the above example, the projected fields could be `student.name, teacher.age`.
And then we can use it to do nested field projection push down.
    What do you think ? 
    Jark Wu

> Add NestedFieldsProjectableTableSource interface
> ------------------------------------------------
>                 Key: FLINK-5698
>                 URL: https://issues.apache.org/jira/browse/FLINK-5698
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table API & SQL
>            Reporter: Anton Solovev
>            Assignee: Anton Solovev
> Add a NestedFieldsProjectableTableSource interface for some TableSource implementation
that support nesting projection push-down.
> The interface could look as follows
> {code}
> def trait NestedFieldsProjectableTableSource {
>   def projectNestedFields(fields: Array[String]): NestedFieldsProjectableTableSource[T]
> }
> {code}
> This interface works together with ProjectableTableSource 

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