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Class type Mapred_def.mapred_job_config


class type mapred_job_config = object .. end

method name : string
A name for identifying this job, e.g. in log files
method job_id : string
An automatically generated name. This can be considered as unique. It is not possible to override this name.
method input_dir : string
This plasma directory contains the input files
method input_dir_designation : designation
How input_dir is interpreted
method output_dir : string
This plasma directory will get output files. It should exist, and it should be empty
method work_dir : string
This plasma directory is used for temporary files. It should exist, and it should be empty
method log_dir : string
This plasma directory is used for log files. It should exist, and it should be empty
method task_files : string list
These files are copied at job start to the "local" directory for this job on all task nodes. This should be regular files only.
method bigblock_size : int
Map/reduce processes files in units of bigblocks. The size of bigblocks can be chosen as multiples of the size of filesystem blocks. The value bigblock_size is in bytes. The maximum size of records (line length) is also bigblock_size. Reasonable values are in the multi-megabyte range, e.g. 16M.

Certain file formats also require that bigblocks are multiples of 64K.

method map_tasks : int
The number of map tasks that should not be exceeded. It is tried to hit this number, but it may be possible that not enough map tasks can be generated.
method merge_limit : int
How many files are merged at most by a shuffle task
method split_limit : int
How many files are created by a shuffle task. This is not a strict limit - actually the scheduler plans with slightly larger split limits near the end of the job.
method partitions : int
The number of partitions = number of reduce tasks
method enhanced_mapping : int
If >0, enhanced map tasks are created. This type of tasks also sorts and pre-partitions data. The int is the number of pre-partitions (must be <= partitions).

Increasing the number of pre-partitions reduces network traffic but makes it more likely that random disk seeks are needed to read data from disk.

method phases : phases
Which phases are enabled
method custom : string -> string
Get a custom parameter or raise Not_found
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