Function date_bin

src/expr/src/scalar/func.rs:2018–2068

(
    stride: Interval,
    source: CheckedTimestamp<T>,
    origin: CheckedTimestamp<T>,
)

}

pub fn date_bin<T>(
    stride: Interval,
    source: CheckedTimestamp<T>,
    origin: CheckedTimestamp<T>,
) -> Result<CheckedTimestamp<T>, EvalError>
where
    T: TimestampLike,
{
    if stride.months != 0 {
        return Err(EvalError::DateBinOutOfRange(
            "timestamps cannot be binned into intervals containing months or years".into(),
        ));
    }

    let stride_ns = match stride.duration_as_chrono().num_nanoseconds() {
        Some(ns) if ns <= 0 => Err(EvalError::DateBinOutOfRange(
            "stride must be greater than zero".into(),
        )),
        Some(ns) => Ok(ns),
        None => Err(EvalError::DateBinOutOfRange(
            format!("stride cannot exceed {}/{} nanoseconds", i64::MAX, i64::MIN,).into(),
        )),
    }?;

    // Make sure the returned timestamp is at the start of the bin, even if the
    // origin is in the future. We do this here because `T` is not `Copy` and
    // gets moved by its subtraction operation.
    let sub_stride = origin > source;

    let tm_diff = (source - origin.clone()).num_nanoseconds().ok_or_else(|| {
        EvalError::DateBinOutOfRange(
            "source and origin must not differ more than 2^63 nanoseconds".into(),
        )
    })?;

    let remainder = tm_diff % stride_ns;
    let mut tm_delta = tm_diff - remainder;

    if sub_stride && remainder != 0 {
        tm_delta = tm_delta.checked_sub(stride_ns).ok_or_else(|| {
            EvalError::DateBinOutOfRange(
                "source and origin must not differ more than 2^63 nanoseconds".into(),
            )
        })?;
    }

    let res = origin
        .checked_add_signed(Duration::nanoseconds(tm_delta))
        .ok_or(EvalError::TimestampOutOfRange)?;
    Ok(CheckedTimestamp::from_timestamplike(res)?)
}

// Non-monotone in `stride`: the result is `origin + floor((source - origin) /
// stride) * stride`. For a fixed source like `2024-01-01 12:00:00`, a 1-day