You can preview data within a mapping in the Developer tool. You can choose sources and transformations in a mapping as preview points. Previewing data helps to design and debug mappings.
You can preview data in streaming mappings configured to run with the following cluster distributions:
The following image shows the run-time properties in the Hadoop execution environment for data preview:
When you configure run-time properties for the Hadoop environment to preview data on streaming jobs in the Data Viewer, consider the following properties:
You can specify the rollover size or rollover time in the
area of the Developer tool. The steps to configure the rollover size and rollover time are similar to the configurations when you run a map. The rollover size is the target file size, in gigabytes(GB), at which to trigger rollover. A value of zero (0) means that the target file does not roll over based on size. Default is 100 bytes. The rollover time is the length of time, in hours, for a target file to roll over. After the time period has elapsed, the target file rolls over. A value of zero (0) means that the target file does not roll over based on time. Default is 1 hour.
You can specify the maximum runtime interval property when you perform data preview on a streaming job in the
area of the Developer tool. Maximum runtime interval is the maximum time to run the mapping before it stops. Default is 2.5 minutes. If you set values for this property and the
Maximum Rows Read
property, the mapping stops running when one of the criteria is met.