Hi Raghu,
No, the order of segments or dimensions in the report definition shouldn't change the data downloaded from your reports. If you haven't set the
includeZeroImpressions header to true, then the report will not include rows for which the requested stats are zero. You have to set this header to true to get zero impressions in the report output.
Could you provide the complete report definition used to download the Shopping Performance Report and also some sample reports that you are comparing? Please use Reply privately to author when you are responding.
Thanks,
Shwetha, AdWords API Team.