Function fastfield_codecs::monotonic_map_column

pub fn monotonic_map_column<C, T, Input, Output>(
    from_column: C,
    monotonic_mapping: T
) -> impl Column<Output>where
    C: Column<Input>,
    T: StrictlyMonotonicFn<Input, Output> + Send + Sync,
    Input: PartialOrd + Send + Sync + Copy + Debug,
    Output: PartialOrd + Send + Sync + Copy + Debug,

Creates a view of a column transformed by a strictly monotonic mapping. See StrictlyMonotonicFn.

E.g. apply a gcd monotonic_mapping([100, 200, 300]) == [1, 2, 3] monotonic_mapping.mapping() is expected to be injective, and we should always have monotonic_mapping.inverse(monotonic_mapping.mapping(el)) == el

The inverse of the mapping is required for: fn get_positions_for_value_range(&self, range: RangeInclusive<T>) -> Vec<u64> The user provides the original value range and we need to monotonic map them in the same way the serialization does before calling the underlying column.

Note that when opening a codec, the monotonic_mapping should be the inverse of the mapping during serialization. And therefore the monotonic_mapping_inv when opening is the same as monotonic_mapping during serialization.