We have one large CSV file that we are looking to transfer in to Parquet and based on the recommended standard of up to 1GB parquet files, splitting across a few files however running in to a few issues
If we don't specify a file within the parquet definition and specify e.g. 10,000,000 rows per file, what we find is the copy activity is autogenerating a subfolder based on the input file name which we don't want.
If we extend 1 to specify a "File name prefix", we get error FileNamePrefixNotSupportFileBasedSource (I note the info box does say you can't specify a prefix with file based sources)
So how do we stop it generating a subfolder based on the source file name? It seems pretty restrictive and illogical to force an unwanted subfolder (a MS trait that hasn't stopped through the years!)





