Function process_map_with_nested_key

datafusion/functions/src/core/getfield.rs:156–191

Process a map array with a nested key type by iterating through entries and using a comparator for key matching. This specialized version is used when the key type is nested (e.g., struct, list).

(
    array: &dyn Array,
    key_array: &dyn Array,
)

///
/// This specialized version is used when the key type is nested (e.g., struct, list).
fn process_map_with_nested_key(
    array: &dyn Array,
    key_array: &dyn Array,
) -> Result<ColumnarValue> {
    let map_array = as_map_array(array)?;

    let comparator =
        make_comparator(map_array.keys().as_ref(), key_array, SortOptions::default())?;

    let original_data = map_array.entries().column(1).to_data();
    let capacity = Capacities::Array(original_data.len());
    let mut mutable =
        MutableArrayData::with_capacities(vec![&original_data], true, capacity);

    for entry in 0..map_array.len() {
        let start = map_array.value_offsets()[entry] as usize;
        let end = map_array.value_offsets()[entry + 1] as usize;

        let mut found_match = false;
        for i in start..end {
            if comparator(i, 0).is_eq() {
                mutable.extend(0, i, i + 1);
                found_match = true;
                break;
            }
        }

        if !found_match {
            mutable.extend_nulls(1);
        }
    }

    let data = mutable.freeze();
    let data = make_array(data);
    Ok(ColumnarValue::Array(data))
}

/// Extract a single field from a struct or map array
fn extract_single_field(base: ColumnarValue, name: ScalarValue) -> Result<ColumnarValue> {