pub struct GroupsAccumulatorAdapter { /* private fields */ }
Expand description

An adapter that implements GroupsAccumulator for any Accumulator

While Accumulator are simpler to implement and can support more general calculations (like retractable window functions), they are not as fast as a specialized GroupsAccumulator. This interface bridges the gap so the group by operator only operates in terms of Accumulator.

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impl GroupsAccumulatorAdapter

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pub fn new<F>(factory: F) -> Selfwhere F: Fn() -> Result<Box<dyn Accumulator>> + Send + 'static,

Create a new adapter that will create a new Accumulator for each group, using the specified factory function

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impl GroupsAccumulator for GroupsAccumulatorAdapter

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fn update_batch( &mut self, values: &[ArrayRef], group_indices: &[usize], opt_filter: Option<&BooleanArray>, total_num_groups: usize ) -> Result<()>

Updates the accumulator’s state from its arguments, encoded as a vector of ArrayRefs. Read more
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fn evaluate(&mut self, emit_to: EmitTo) -> Result<ArrayRef>

Returns the final aggregate value for each group as a single RecordBatch, resetting the internal state. Read more
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fn state(&mut self, emit_to: EmitTo) -> Result<Vec<ArrayRef>>

Returns the intermediate aggregate state for this accumulator, used for multi-phase grouping, resetting its internal state. Read more
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fn merge_batch( &mut self, values: &[ArrayRef], group_indices: &[usize], opt_filter: Option<&BooleanArray>, total_num_groups: usize ) -> Result<()>

Merges intermediate state (the output from Self::state) into this accumulator’s values. Read more
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fn size(&self) -> usize

Amount of memory used to store the state of this accumulator, in bytes. This function is called once per batch, so it should be O(n) to compute, not O(num_groups)

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> Same<T> for T

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type Output = T

Should always be Self
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for Twhere V: MultiLane<T>,

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fn vzip(self) -> V