[−][src]Trait datafusion::execution::physical_plan::AggregateExpr

pub trait AggregateExpr: Send + Sync {
    fn name(&self) -> String;

    fn data_type(&self, input_schema: &Schema) -> Result<DataType>;

    fn create_accumulator(&self) -> Rc<RefCell<dyn Accumulator>>;

    fn create_combiner(&self, column_index: usize) -> Arc<dyn AggregateExpr>;
}

Agggregate expression that can be evaluated against a RecordBatch

Required methods

fn name(&self) -> String

Get the name to use in a schema to represent the result of this expression

fn data_type(&self, input_schema: &Schema) -> Result<DataType>

Get the data type of this expression, given the schema of the input

fn create_accumulator(&self) -> Rc<RefCell<dyn Accumulator>>

Create an accumulator for this aggregate expression

fn create_combiner(&self, column_index: usize) -> Arc<dyn AggregateExpr>

Create an aggregate expression for combining the results of accumulators from partitions. For example, to combine the results of a parallel SUM we just need to do another SUM, but to combine the results of parallel COUNT we would also use SUM.

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Implementors

impl AggregateExpr for Sum[src]

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