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

pub trait AggregateExpr: Send + Sync + Debug {
    fn field(&self) -> Result<Field>;
    fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>;
    fn state_fields(&self) -> Result<Vec<Field>>;
    fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>;
}

An aggregate expression that:

knows its resulting field
knows how to create its accumulator
knows its accumulator's state's field
knows the expressions from whose its accumulator will receive values

Required methods

`fn field(&self) -> Result<Field>`[src]

the field of the final result of this aggregation.

`fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>`[src]

the accumulator used to accumulate values from the expressions. the accumulator expects the same number of arguments as expressions and must return states with the same description as state_fields

`fn state_fields(&self) -> Result<Vec<Field>>`[src]

the fields that encapsulate the Accumulator's state the number of fields here equals the number of states that the accumulator contains

`fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>`[src]

expressions that are passed to the Accumulator. Single-column aggregations such as sum return a single value, others (e.g. cov) return many.

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Implementors

`impl AggregateExpr for DistinctCount`[src]

`fn field(&self) -> Result<Field>`[src]

`fn state_fields(&self) -> Result<Vec<Field>>`[src]

`fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>`[src]

`fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>`[src]

`impl AggregateExpr for Avg`[src]

`fn field(&self) -> Result<Field>`[src]

`fn state_fields(&self) -> Result<Vec<Field>>`[src]

`fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>`[src]

`fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>`[src]

`impl AggregateExpr for Count`[src]

`fn field(&self) -> Result<Field>`[src]

`fn state_fields(&self) -> Result<Vec<Field>>`[src]

`fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>`[src]

`fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>`[src]

`impl AggregateExpr for Max`[src]

`fn field(&self) -> Result<Field>`[src]

`fn state_fields(&self) -> Result<Vec<Field>>`[src]

`fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>`[src]

`fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>`[src]

`impl AggregateExpr for Min`[src]

`fn field(&self) -> Result<Field>`[src]

`fn state_fields(&self) -> Result<Vec<Field>>`[src]

`fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>`[src]

`fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>`[src]

`impl AggregateExpr for Sum`[src]

`fn field(&self) -> Result<Field>`[src]

`fn state_fields(&self) -> Result<Vec<Field>>`[src]

`fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>`[src]

`fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>`[src]

`impl AggregateExpr for AggregateFunctionExpr`[src]

`fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>`[src]

`fn state_fields(&self) -> Result<Vec<Field>>`[src]

`fn field(&self) -> Result<Field>`[src]

`fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>`[src]

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