Function append_schema_ddl 

pub(crate) fn append_schema_ddl<'a>(
    client: &'a DatabaseClient,
    catalog: &'a str,
    schema: &'a str,
    objects: impl Iterator<Item = (&'static str, Option<&'a str>)> + Send + 'a,
    ddl: &'a mut String,
) -> impl Future<Output = Result<()>> + Send + 'a

Appends DDL in dependency order supplied by the caller using bounded requests.