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# orch.dryrun

Switches the execution platform between the local host and the Hadoop cluster. No changes in the R code are required for a dry run.

Usage

    orch.dryrun(onoff)

Arguments

onoff

  Set to `TRUE` to run a MapReduce program locally, or `FALSE` to run the program on the Hadoop cluster.

Usage Notes

The `orch.dryrun` function enables you to run a MapReduce program locally on a laptop using a small data set before running it on a Hadoop cluster using a very large data set. The mappers and reducers are run sequentially on row streams from HDFS. The Hadoop cluster is not required for a dry run.

Return Value

The current setting of `orch.dryrun`

See Also

`hadoop.exec`, `hadoop.run`

Example

This example changes the value of `orch.dryrun` from `FALSE` to `TRUE`.

    R> orch.dryrun()
    [1] FALSE
    R> orch.dryrun(onoff<-T)
    R> orch.dryrun()
    [1] TRUE