manjunathsinghs - you are correct that the Append option in the File Writer snap is only supported by a few protocols - this is the nature of the protocol itself, not SnapLogic.
I'm unclear on your full requirements here but if you are simply paginating through results and writing to the file, then the file should at least contain the full set of responses returned in the pipeline execution unless you have something in your design or snap properties that is not streaming the data through to the target file.
If you need further assistance, can you export your pipeline and attach to this thread?
