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From apivovarov <...@git.apache.org>
Subject [GitHub] flink pull request #2485: [Flink 4599] - Add 'explain()' also to StreamTable...
Date Sat, 10 Sep 2016 04:16:45 GMT
Github user apivovarov commented on a diff in the pull request:

    https://github.com/apache/flink/pull/2485#discussion_r78270796
  
    --- Diff: docs/dev/table_api.md ---
    @@ -2457,3 +2457,27 @@ The Table API provides a configuration (the so-called `TableConfig`)
to modify r
     By default, the Table API supports `null` values. Null handling can be disabled to improve
preformance by setting the `nullCheck` property in the `TableConfig` to `false`.
     
     {% top %}
    +
    +Explaining a Table
    +----
    +The Table API provides a mechanism to describe the graph of operations that leads to
the resulting output. This is done through the `TableEnvironment#explain(table)` method. It
returns a string describing two graphs: the Abstract Syntax Tree of the relational algebra
query and the Flink's Execution Plan of the equivalent Flink's Job. 
    +
    +Table `explain` is supported for both `BatchTableEnvironment` and `StreamTableEnvironment`.
Currently `StreamTableEnvironment` doesn't support the explanation of the Execution Plan.
    +
    +
    +<div data-lang="scala" markdown="1">
    +{% highlight scala %}
    +	val env = StreamExecutionEnvironment.getExecutionEnvironment
    +	val tEnv = TableEnvironment.getTableEnvironment(env)
    +
    +	val table1 = env.fromElements((1, "hello")).toTable(tEnv, 'count, 'word)
    +	val table2 = env.fromElements((1, "hello")).toTable(tEnv, 'count, 'word)
    +	val table = table1.unionAll(table2)
    +
    +	val explanation:String = tEnv.explain(table)
    --- End diff --
    
    put space before String


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