Struct datafusion::physical_plan::expressions::Count

pub struct Count { /* fields omitted */ }

COUNT aggregate expression Returns the amount of non-null values of the given expression.

Implementations

impl Count

pub fn new(
    expr: Arc<dyn PhysicalExpr>,
    name: String,
    data_type: DataType
) -> Self

Create a new COUNT aggregate function.

Trait Implementations

impl AggregateExpr for Count

fn as_any(&self) -> &dyn Any

Return a reference to Any that can be used for downcasting

fn field(&self) -> Result<Field>

the field of the final result of this aggregation.

fn state_fields(&self) -> Result<Vec<Field>>

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>>

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

fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>

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

impl Debug for Count

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.