Struct DecimalTrack 

pub struct DecimalTrack {
    pub scale: u8,
    pub sum: i128,
    pub min: i128,
    pub max: i128,
    pub first: i128,
    pub last: i128,
    pub overflow: bool,
}

The exact half of an accumulator, allocated only for decimal columns.

Boxed behind an Option so a float column pays eight bytes for it and nothing else — a group-by over a high-cardinality tag holds one accumulator per (group, field), and making every one of them 128 bytes wider to support a column type it does not have is a cost the gateway would feel.

Fields

scale: u8

The scale everything tracked here is expressed at.

sum: i128

Running total.

min: i128

Smallest mantissa seen.

max: i128

Largest mantissa seen.

first: i128

Mantissa at the earliest timestamp.

last: i128

Mantissa at the latest timestamp.

overflow: bool

A sum or a rescale needed more than 38 significant digits. The affected results are NULL: a number that is not the answer is worse than no number.

Implementations

impl DecimalTrack

pub fn new(scale: u8) -> Self

An empty track at scale.

pub fn widen_to(&mut self, scale: u8)

Re-express everything tracked so far at a wider scale.

pub fn align(&mut self, mantissa: i128, scale: u8) -> Option<i128>

Bring an incoming mantissa to the track’s scale, widening the track if the incoming value is finer. Both directions are exact.

Returns None when the alignment would overflow 38 digits; the caller sets overflow.

pub fn sum_result(&self) -> AggResult

The sum, or Null if it overflowed 38 digits.

pub fn avg_result(&self, count: u64) -> AggResult

The mean, carried to AVG_EXTRA_SCALE extra digits and rounded half away from zero. See that constant for why this is the one aggregate that rounds.

pub fn at(&self, mantissa: i128) -> AggResult

One tracked mantissa as a result.

Trait Implementations

impl Clone for DecimalTrack

fn clone(&self) -> DecimalTrack

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DecimalTrack

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.