I would not count on order preserving nature of the operations, because it is not guranteed. I would assign some order to the sentences and sort at the end before write back

On Fri, 27 Jan 2017 at 10:59 pm, Md. Rezaul Karim <rezaul.karim@insight-centre.org> wrote:
Some operations like map, filter, flatMap and coalesce (with shuffle=false) usually preserve the order. However, sortBy, reduceBy, partitionBy, join etc. do not.

Md. Rezaul Karim, BSc, MSc
PhD Researcher, INSIGHT Centre for Data Analytics
National University of Ireland, Galway
IDA Business Park, Dangan, Galway, Ireland

On 27 January 2017 at 09:44, Soheila S. <soheila518@gmail.com> wrote:
Hi All,
I read a test file using sparkContext.textfile(filename) and assign it to an RDD and process the RDD (replace some words) and finally write it to a text file using rdd.saveAsTextFile(output).
Is there any way to be sure the order of the sentences will not be changed? I need to have the same text with some corrected words.



Best Regards,
Ayan Guha