Trait tidb_query_aggr::impl_variance::VarianceType[−][src]

pub trait VarianceType: Clone + Debug + Send + Sync + 'static {
    fn check_expr_type(tt: ExprType) -> bool;

    fn compute_final_variance<T: Summable>(
        variance: &T, 
        count: usize
    ) -> Result<T>;
}

A trait for VARIANCE aggregation functions

Required methods

fn check_expr_type(tt: ExprType) -> bool[src]

Checks whether the given expression type refers to the type of variance.

fn compute_final_variance<T: Summable>(variance: &T, count: usize) -> Result<T>[src]

Computes the final variance of values.

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Implementors

impl VarianceType for Population[src]

impl VarianceType for Sample[src]

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