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https://issues.apache.org/jira/browse/FLINK-2828?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15258282#comment-15258282
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ASF GitHub Bot commented on FLINK-2828:
---------------------------------------

Github user vasia commented on the pull request:

    https://github.com/apache/flink/pull/1939#issuecomment-214782320
  
    Thanks @fhueske, PR looks good :)
    Maybe we can refactor the source RelNode to avoid much code duplication. 
And do you think we need a test for `CsvTableSource`?


> Add interfaces for Table API input formats
> ------------------------------------------
>
>                 Key: FLINK-2828
>                 URL: https://issues.apache.org/jira/browse/FLINK-2828
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table API
>            Reporter: Timo Walther
>            Assignee: Fabian Hueske
>
> In order to support input formats for the Table API, interfaces are 
> necessary. I propose two types of TableSources:
> - AdaptiveTableSources can adapt their output to the requirements of the 
> plan. Although the output schema stays the same, the TableSource can react on 
> field resolution and/or predicates internally and can return adapted 
> DataSet/DataStream versions in the "translate" step.
> - StaticTableSources are an easy way to provide the Table API with additional 
> input formats without much implementation effort (e.g. for fromCsvFile())
> TableSources need to be deeply integrated into the Table API.
> The TableEnvironment requires a newly introduced AbstractExecutionEnvironment 
> (common super class of all ExecutionEnvironments for DataSets and 
> DataStreams).
> Here's what a TableSource can see from more complicated queries:
> {code}
> getTableJava(tableSource1)
>   .filter("a===5 || a===6")
>   .select("a as a4, b as b4, c as c4")
>   .filter("b4===7")
>   .join(getTableJava(tableSource2))
>   .where("a===a4 && c==='Test' && c4==='Test2'")
> // Result predicates for tableSource1:
> //  List("a===5 || a===6", "b===7", "c==='Test2'")
> // Result predicates for tableSource2:
> //  List("c==='Test'")
> // Result resolved fields for tableSource1 (true = filtering, 
> false=selection):
> //  Set(("a", true), ("a", false), ("b", true), ("b", false), ("c", false), 
> ("c", true))
> // Result resolved fields for tableSource2 (true = filtering, 
> false=selection):
> //  Set(("a", true), ("c", true))
> {code}



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