Function append 

pub async fn append(
    dataset: &mut Dataset,
    rows: impl Stream<Item = Result<NdRecordBatch>>,
    options: &WriteOptions,
) -> Result<()>

Append a stream of rows to the table of dataset in one commit. Each nd record batch is one row. A failed row commits nothing.

The append starts from the latest version of the table. dataset then holds the new version.