Function widen_schema

benchmarks/src/bin/gen_wide_data.rs:189–209

Builds the wide schema by laying out the suffix-renamed zero-padded copies first and the unsuffixed base columns last. Putting the base columns at the *end* of the schema is deliberate — column lookup for the filter / project columns has to traverse past all the padding entries, exercising any per-column-position cost in the scanner / planner.

(src: &SchemaRef, factor: usize)

/// padding entries, exercising any per-column-position cost in the
/// scanner / planner.
fn widen_schema(src: &SchemaRef, factor: usize) -> SchemaRef {
    let src_fields = src.fields();
    let mut fields: Vec<Arc<Field>> = Vec::with_capacity(src_fields.len() * factor);
    for copy in 2..=factor {
        for f in src_fields {
            fields.push(Arc::new(Field::new(
                format!("{}_{}", f.name(), copy),
                f.data_type().clone(),
                true,
            )));
        }
    }
    for f in src_fields {
        fields.push(Arc::new(Field::new(
            f.name().clone(),
            f.data_type().clone(),
            f.is_nullable(),
        )));
    }
    Arc::new(Schema::new(fields))
}

fn widen_batch(
    batch: &RecordBatch,