Struct StateWrapper

pub struct StateWrapper {
    inner: AggregateUDF,
    name: String,
}

Wrapper to make an aggregate function out of a state function.

Fields

inner: AggregateUDF

name: String

Implementations

impl StateWrapper

pub fn new(inner: AggregateUDF) -> Result<Self>

state_index: The index of the state in the output of the state function.

pub fn inner(&self) -> &AggregateUDF

pub fn deduce_aggr_return_type( &self, acc_args: &AccumulatorArgs<'_>, ) -> Result<DataType>

Deduce the return type of the original aggregate function based on the accumulator arguments.

Trait Implementations

impl AggregateUDFImpl for StateWrapper

fn return_type(&self, arg_types: &[DataType]) -> Result<DataType>

Return state_fields as the output struct type.

fn state_fields(&self, args: StateFieldsArgs<'_>) -> Result<Vec<Field>>

The state function’s output fields are the same as the original aggregate function’s state fields.

fn signature(&self) -> &Signature

The state function’s signature is the same as the original aggregate function’s signature,

fn coerce_types(&self, arg_types: &[DataType]) -> Result<Vec<DataType>>

Coerce types also do nothing, as optimzer should be able to already make struct types

fn accumulator<'a, 'b>( &'a self, acc_args: AccumulatorArgs<'b>, ) -> Result<Box<dyn Accumulator>>

Return a new [Accumulator] that aggregates values for a specific group during query execution.

fn as_any(&self) -> &dyn Any

Returns this object as an Any trait object

fn name(&self) -> &str

Returns this function’s name

fn is_nullable(&self) -> bool

Whether the aggregate function is nullable.

fn groups_accumulator_supported(&self, _args: AccumulatorArgs<'_>) -> bool

If the aggregate expression has a specialized [GroupsAccumulator] implementation. If this returns true, [Self::create_groups_accumulator] will be called.

fn create_groups_accumulator( &self, _args: AccumulatorArgs<'_>, ) -> Result<Box<dyn GroupsAccumulator>, DataFusionError>

Return a specialized [GroupsAccumulator] that manages state for all groups.

fn aliases(&self) -> &[String]

Returns any aliases (alternate names) for this function.

fn create_sliding_accumulator( &self, args: AccumulatorArgs<'_>, ) -> Result<Box<dyn Accumulator>, DataFusionError>

Sliding accumulator is an alternative accumulator that can be used for window functions. It has retract method to revert the previous update.

fn with_beneficial_ordering( self: Arc<Self>, _beneficial_ordering: bool, ) -> Result<Option<Arc<dyn AggregateUDFImpl>>, DataFusionError>

Sets the indicator whether ordering requirements of the AggregateUDFImpl is satisfied by its input. If this is not the case, UDFs with order sensitivity AggregateOrderSensitivity::Beneficial can still produce the correct result with possibly more work internally.

fn order_sensitivity(&self) -> AggregateOrderSensitivity

Gets the order sensitivity of the UDF. See [AggregateOrderSensitivity] for possible options.

fn simplify( &self, ) -> Option<Box<dyn Fn(AggregateFunction, &dyn SimplifyInfo) -> Result<Expr, DataFusionError>>>

Optionally apply per-UDaF simplification / rewrite rules.

fn reverse_expr(&self) -> ReversedUDAF

Returns the reverse expression of the aggregate function.

fn equals(&self, other: &dyn AggregateUDFImpl) -> bool

Return true if this aggregate UDF is equal to the other.

fn hash_value(&self) -> u64

Returns a hash value for this aggregate UDF.

fn is_descending(&self) -> Option<bool>

If this function is max, return true If the function is min, return false Otherwise return None (the default)

fn value_from_stats( &self, _statistics_args: &StatisticsArgs<'_>, ) -> Option<ScalarValue>

Return the value of this aggregate function if it can be determined entirely from statistics and arguments.

fn default_value( &self, data_type: &DataType, ) -> Result<ScalarValue, DataFusionError>

Returns default value of the function given the input is all null.

fn documentation(&self) -> Option<&Documentation>

Returns the documentation for this Aggregate UDF.

fn set_monotonicity(&self, _data_type: &DataType) -> SetMonotonicity

Indicates whether the aggregation function is monotonic as a set function. See [SetMonotonicity] for details.

impl Clone for StateWrapper

fn clone(&self) -> StateWrapper

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StateWrapper

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

Formats the value using the given formatter.

impl PartialEq for StateWrapper

fn eq(&self, other: &StateWrapper) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for StateWrapper

impl StructuralPartialEq for StateWrapper