AggregateFunction

sql_cli::sql::aggregates

Trait AggregateFunction 

Source 
pub trait AggregateFunction: Send + Sync {
    // Required methods
    fn name(&self) -> &str;
    fn init(&self) -> AggregateState;
    fn accumulate(
        &self,
        state: &mut AggregateState,
        value: &DataValue,
    ) -> Result<()>;
    fn finalize(&self, state: AggregateState) -> DataValue;

    // Provided method
    fn requires_numeric(&self) -> bool { ... }
}
Expand description

Trait for all aggregate functions

Required Methods§

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fn name(&self) -> &str

Name of the function (e.g., “SUM”, “AVG”)

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fn init(&self) -> AggregateState

Initialize the aggregation state

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fn accumulate( &self, state: &mut AggregateState, value: &DataValue, ) -> Result<()>

Add a value to the aggregation

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fn finalize(&self, state: AggregateState) -> DataValue

Finalize and return the result

Provided Methods§

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fn requires_numeric(&self) -> bool

Check if this function requires numeric input

Implementors§