flink-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
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 20:53:10 GMT

    [ https://issues.apache.org/jira/browse/FLINK-6442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16170686#comment-16170686
] 

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_r139525263
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/TableEnvironment.scala
---
    @@ -502,23 +521,130 @@ abstract class TableEnvironment(val config: TableConfig) {
         * @param query The SQL query to evaluate.
         * @return The result of the query as Table.
         */
    +  @deprecated("use [[sqlQuery()]] instead")
       def sql(query: String): Table = {
    +    sqlQuery(query)
    +  }
    +
    +  /**
    +    * Evaluates a SQL Select query on registered tables and retrieves the result as a
    +    * [[Table]].
    +    *
    +    * All tables referenced by the query must be registered in the TableEnvironment.
But
    +    * [[Table.toString]] will automatically register an unique table name and return
the
    +    * table name. So it allows to call SQL directly on tables like this:
    +    *
    +    * {{{
    +    *   val table: Table = ...
    +    *   // the table is not registered to the table environment
    +    *   tEnv.sqlSelect(s"SELECT * FROM $table")
    +    * }}}
    +    *
    +    * @param query The SQL query to evaluate.
    +    * @return The result of the query as Table
    +    */
    +  def sqlQuery(query: String): Table = {
         val planner = new FlinkPlannerImpl(getFrameworkConfig, getPlanner, getTypeFactory)
         // parse the sql query
         val parsed = planner.parse(query)
    -    // validate the sql query
    -    val validated = planner.validate(parsed)
    -    // transform to a relational tree
    -    val relational = planner.rel(validated)
    +    if (null != parsed && parsed.getKind.belongsTo(SqlKind.QUERY)) {
    +      // validate the sql query
    +      val validated = planner.validate(parsed)
    +      // transform to a relational tree
    +      val relational = planner.rel(validated)
    +      new Table(this, LogicalRelNode(relational.rel))
    +    } else {
    +      throw new TableException(
    +        "Unsupported SQL query! sqlQuery() only accepts SQL queries of type SELECT, UNION,
" +
    +          "INTERSECT, EXCEPT, VALUES, WITH, ORDER_BY, and EXPLICIT_TABLE.")
    +    }
    +  }
    +
    +  /**
    +    * Evaluates a SQL statement such as INSERT, UPDATE or DELETE; or a DDL statement;
    +    * Currently only SQL INSERT statement on registered tables are supported.
    +    *
    +    * All tables referenced by the query must be registered in the TableEnvironment.
But
    --- End diff --
    
    Rephrase: "A [[Table]] is automatically registered when the [[Table.toString()]] method
is called, i.e., when it is embedded into a string. Hence, SQL queries can directly reference
a [[Table]] as follows: "


> 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



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

Mime
View raw message