Enum ModelType 

pub enum ModelType {
    Positional,
    Named,
}

Whether a relation’s attributes are identified by name or by position.

Returned by RelationHeader::model_type. A header is Named when it carries explicit attribute names (e.g. from a CSV/Parquet schema), and Positional otherwise — typical for intermediate relations produced during query evaluation where only arity matters.

Variants

Positional

Attributes are accessed by column index only; attribute names are absent.

Named

Attributes have explicit string names, typically sourced from a file header or schema.