You can generate output files from source-based or user-defined commits. You can use a source-based commit to commit data to a target file based on the number of rows from a source. For example, you might want to create a separate output file for each 1,000 rows of data. You can configure a user-defined commit when the mapping contains an effective transaction generator. For example, you might want to create a separate output file for each city.
In a mapping, connect the target FileName port to a transformation port that will contain a unique value at the start of each transaction. You can create an expression in the transformation to generate unique file names and pass them to the FileName port.