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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-6442) Extend TableAPI Support Sink Table Registration and ‘insert into’ Clause in SQL
Date Tue, 19 Sep 2017 02:25:02 GMT

    [ https://issues.apache.org/jira/browse/FLINK-6442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16171012#comment-16171012
] 

ASF GitHub Bot commented on FLINK-6442:
---------------------------------------

Github user lincoln-lil commented on a diff in the pull request:

    https://github.com/apache/flink/pull/3829#discussion_r139582270
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala
---
    @@ -762,13 +763,10 @@ class Table(
         * @tparam T The data type that the [[TableSink]] expects.
         */
       def writeToSink[T](sink: TableSink[T]): Unit = {
    -
    -    def queryConfig = this.tableEnv match {
    -      case s: StreamTableEnvironment => s.queryConfig
    -      case b: BatchTableEnvironment => new BatchQueryConfig
    -      case _ => null
    +    val queryConfig = Option(this.tableEnv) match {
    --- End diff --
    
    I did think so but encounter a NPE when test `CorrelateValidationTest.testInvalidTableFunction`
    ```
     // table function call writeToSink
        expectExceptionThrown(
          func1('c).writeToSink(null),
          "Cannot translate a query with an unbounded table function call."
        )
    ```
     so I add the `Option` here.


> Extend TableAPI Support Sink Table Registration and ‘insert into’ Clause in SQL
> -------------------------------------------------------------------------------
>
>                 Key: FLINK-6442
>                 URL: https://issues.apache.org/jira/browse/FLINK-6442
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table API & SQL
>            Reporter: lincoln.lee
>            Assignee: lincoln.lee
>            Priority: Minor
>
> Currently in TableAPI  there’s only registration method for source table,  when we
use SQL writing a streaming job, we should add additional part for the sink, like TableAPI
does:
> {code}
> val sqlQuery = "SELECT * FROM MyTable WHERE _1 = 3"
> val t = StreamTestData.getSmall3TupleDataStream(env)
> tEnv.registerDataStream("MyTable", t)
> // one way: invoke tableAPI’s writeToSink method directly
> val result = tEnv.sql(sqlQuery)
> result.writeToSink(new YourStreamSink)
> // another way: convert to datastream first and then invoke addSink 
> val result = tEnv.sql(sqlQuery).toDataStream[Row]
> result.addSink(new StreamITCase.StringSink)
> {code}
> From the api we can see the sink table always be a derived table because its 'schema'
is inferred from the result type of upstream query.
> Compare to traditional RDBMS which support DML syntax, a query with a target output could
be written like this:
> {code}
> insert into table target_table_name
> [(column_name [ ,...n ])]
> query
> {code}
> The equivalent form of the example above is as follows:
> {code}
>     tEnv.registerTableSink("targetTable", new YourSink)
>     val sql = "INSERT INTO targetTable SELECT a, b, c FROM sourceTable"
>     val result = tEnv.sql(sql)
> {code}
> It is supported by Calcite’s grammar: 
> {code}
>  insert:( INSERT | UPSERT ) INTO tablePrimary
>  [ '(' column [, column ]* ')' ]
>  query
> {code}
> I'd like to extend Flink TableAPI to support such feature.  see design doc: https://goo.gl/n3phK5



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