Map-Reduce (MR) Action Parameters
Table 7.32. MR Action, General Parameters
| Parameter Name | Description | Additional Information | Example |
|---|---|---|---|
| Mapper Class | Specifies the Java class that should be used as mapper. | The JAR containing the class must be available in the Oozie classpath or in the lib directory. | |
| Reducer Class | Specifies the Java class that should be used as reducer. | The JAR containing the class must be available in the Oozie classpath or in the lib directory. | |
| No of Tasks | The default number of map tasks per job. | This setting is ignored if the mapred.job.tracker parameter is set to "local". | |
| Input Dir | |||
| Output Dir | The directory to contain the job output. | Hadoop verifies that the job output directory does not exist, and then creates it when the job starts. | |
| Job XML | You can select one or more job.xml files to pass Map-Reduce configuration details. | The configuration file that specifies the variables used for the Map-Reduce action in the workflow. Can be overwritten or replaced by entries under the Configuration section. |
Table 7.33. MR Action, Transition Parameters
| Parameter Name | Description | Additional Information | Default Setting |
|---|---|---|---|
| Error To | Indicates what action to take if the action errors out. | You can modify this setting in the dialog box or by modifying the workflow graph. | Defaults to kill node, but can be changed. |
| OK To | Indicates what node to transition to if the action succeeds. | You can modify this setting in the dialog box or by modifying the workflow graph. | Defaults to the next node in the workflow. |
Table 7.34. MR Action, Advanced Properties Parameters
| Parameter Name | Description | Additional Information | Example |
|---|---|---|---|
| Resource Manager | Master node that arbitrates all the available cluster resources among the competing applications. | The default setting is discovered from the cluster configuration. | ${resourceManager} |
| Name Node | Manages the file system metadata. | Keeps the directory tree of all files in the file system, and tracks where across the cluster the file data is kept. Clients contact NameNode for file metadata or file modifications. | ${nameNode} |
| File | Select any files that you want to make available to the Map-Reduce action when the workflow runs. | Commonly used for streaming jobs that require files in HDFS to be available to the mapper/reducer scripts. | /path/file |
| Archive | Select any archives that you want to make available to the Map-Reduce action when the workflow runs. | Commonly used for streaming jobs that require files in HDFS to be available to the mapper/reducer scripts. | /path/archived-data-files |
| Prepare | Select mkdir or delete and identify any HDFS paths to create or delete before starting the job. | Use delete to do file cleanup prior to job execution. Enables Oozie to retry a job if there is a transient failure (the job output directory must not exist prior to job start). If the path is to a directory: delete deletes all content recursively and then deletes the directory. mkdir creates all missing directories in the path. |
Table 7.35. MR Action, Configuration Parameters
| Parameter Name | Description | Additional Information | Example |
|---|---|---|---|
| Name and Value | The name/value pair can be used instead of a job.xml file or can override parameters set in the job.xml file. |
Used to specify formal parameters. If the name and value are specified, the user can override the values from the Submit dialog box. Can be parameterized (templatized) using EL expressions. The configuration properties are loaded in the following order: streaming, job-xml, and configuration. Later values override earlier values. |