Method join

datafusion/common/src/dfschema.rs:287–307

Create a new schema that contains the fields from this schema followed by the fields from the supplied schema. An error will be returned if there are duplicate field names.

(&self, schema: &DFSchema)

    /// Create a new schema that contains the fields from this schema followed by the fields
    /// from the supplied schema. An error will be returned if there are duplicate field names.
    pub fn join(&self, schema: &DFSchema) -> Result<Self> {
        let mut schema_builder = SchemaBuilder::new();
        schema_builder.extend(self.inner.fields().iter().cloned());
        schema_builder.extend(schema.fields().iter().cloned());
        let new_schema = schema_builder.finish();

        let mut new_metadata = self.inner.metadata.clone();
        new_metadata.extend(schema.inner.metadata.clone());
        let new_schema_with_metadata = new_schema.with_metadata(new_metadata);

        let mut new_qualifiers = self.field_qualifiers.clone();
        new_qualifiers.extend_from_slice(schema.field_qualifiers.as_slice());

        let new_self = Self {
            inner: Arc::new(new_schema_with_metadata),
            field_qualifiers: new_qualifiers,
            functional_dependencies: FunctionalDependencies::empty(),
        };
        new_self.check_names()?;
        Ok(new_self)
    }

    /// Modify this schema by appending the fields from the supplied schema, ignoring any
    /// duplicate fields.