Github user uce commented on a diff in the pull request: https://github.com/apache/flink/pull/774#discussion_r31703506 --- Diff: docs/apis/programming_guide.md --- @@ -394,26 +382,66 @@ def write(outputFormat: FileOutputFormat[T], writeMode: WriteMode = WriteMode.NO_OVERWRITE) def print() -{% endhighlight %} -The last method is only useful for developing/debugging on a local machine, -it will output the contents of the DataSet to standard output. (Note that in -a cluster, the result goes to the standard out stream of the cluster nodes and ends -up in the *.out* files of the workers). -The first two do as the name suggests, the third one can be used to specify a -custom data output format. Please refer -to [Data Sinks](#data-sinks) for more information on writing to files and also -about custom data output formats. - -Once you specified the complete program you need to call `execute` on -the `ExecutionEnvironment`. This will either execute on your local -machine or submit your program for execution on a cluster, depending on -how you created the execution environment. +def collect() +{% endhighlight %} </div> </div> +The first two methods (`writeAsText()` and `writeAsCsv()`) do as the name suggests, the third one +can be used to specify a custom data output format. Please refer to [Data Sinks](#data-sinks) for +more information on writing to files and also about custom data output formats. + +The `print()` method is useful for developing/debugging. It will output the contents of the DataSet +to standard output (on the JVM starting the Flink execution). **NOTE** The behavior of the `print()` +method changed with Flink 0.9.x. Before it was printing to the log file of the workers, now its +sending the DataSet results to the client and printing the results there. + +`collect()` allows to retrieve the DataSet from the cluster to the local JVM. The `collect()` method +will return a `List` containing the elements. + +Both `print()` and `collect()` will trigger the execution of the program. --- End diff -- Let's be explicit. Something along the lines of: ...trigger execution of the program. You don't need a further call to `execute()`.
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