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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 Mon, 18 Sep 2017 20:53:11 GMT

    [ https://issues.apache.org/jira/browse/FLINK-6442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16170693#comment-16170693
] 

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

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/3829#discussion_r139530317
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala
---
    @@ -800,6 +798,68 @@ class Table(
       }
     
       /**
    +    * Writes the [[Table]] to a [[TableSink]] specified by given name. The tableName
    +    * represents a registered [[TableSink]] which defines an external storage location.
    +    *
    +    * A batch [[Table]] can only be written to a
    +    * [[org.apache.flink.table.sinks.BatchTableSink]], a streaming [[Table]] requires
a
    +    * [[org.apache.flink.table.sinks.AppendStreamTableSink]], a
    +    * [[org.apache.flink.table.sinks.RetractStreamTableSink]], or an
    +    * [[org.apache.flink.table.sinks.UpsertStreamTableSink]].*
    +    *
    +    * @param tableName Name of the [[TableSink]] to which the [[Table]] is written.
    +    */
    +  def insertInto(tableName: String): Unit = {
    +    insertInto(tableName, this.tableEnv.queryConfig)
    +  }
    +
    +  /**
    +    * Writes the [[Table]] to a [[TableSink]] specified by given name. The tableName
    +    * represents a registered [[TableSink]] which defines an external storage location.
    +    *
    +    * A batch [[Table]] can only be written to a
    +    * [[org.apache.flink.table.sinks.BatchTableSink]], a streaming [[Table]] requires
a
    +    * [[org.apache.flink.table.sinks.AppendStreamTableSink]], a
    +    * [[org.apache.flink.table.sinks.RetractStreamTableSink]], or an
    +    * [[org.apache.flink.table.sinks.UpsertStreamTableSink]].*
    +    *
    +    * @param tableName Name of the [[TableSink]] to which the [[Table]] is written.
    +    * @param conf The [[QueryConfig]] to use.
    +    */
    +  def insertInto(tableName: String, conf: QueryConfig): Unit = {
    +    require(tableName != null && !tableName.isEmpty, "tableSink must not be null
or empty.")
    +    // validate if the tableSink is registered
    +    if (!tableEnv.isRegistered(tableName)) {
    --- End diff --
    
    I think it is better to move the implementation to a method `TableEnvironment.insertTableInto(table:
Table, sinkTable: String, conf: QueryConfig)`. This would also allow to make `TableEnvironment.getTable()`
`private`.


> 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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