Function execute 

pub(crate) async fn execute(
    flow: &StatelessFlow,
    rows: &[(Row, i64, i64)],
    batch_datatypes: &[ConcreteDataType],
    query_engine: &Arc<dyn QueryEngine>,
    frontend_client: &Arc<FrontendClient>,
    current_source_schema_version: u32,
) -> Result<usize, Error>

Executes one mirror write using only the supplied batch and writes its output.