Struct ArrowPredicateFn

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pub struct ArrowPredicateFn<F> {
    f: F,
    projection: ProjectionMask,
}
Expand description

An ArrowPredicate created from an FnMut and a ProjectionMask

See RowFilter for more information on applying filters during the Parquet decoding process.

The function is passed RecordBatches with only the columns specified in the ProjectionMask.

The function must return a [BooleanArray] that has the same length as the input batch where each row indicates whether the row should be returned:

  • true: the row should be returned
  • false or null: the row should not be returned

§Example:

Given an input schema: "a:int64", "b:int64", you can create a predicate that evaluates b > 0 like this:

// Create a mask for selecting only the second column "b" (index 1)
let projection_mask = ProjectionMask::leaves(&descriptor, [1]);
// Closure that evaluates "b > 0"
let predicate = |batch: RecordBatch| {
   let scalar_0 = Int64Array::new_scalar(0);
   let column = batch.column(0).as_primitive::<Int64Type>();
   // call the gt kernel to compute `>` which returns a BooleanArray
   gt(column, &scalar_0)
 };
// Create ArrowPredicateFn that can be passed to RowFilter
let arrow_predicate = ArrowPredicateFn::new(projection_mask, predicate);

Fields§

§f: F§projection: ProjectionMask

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impl<F> ArrowPredicateFn<F>
where F: FnMut(RecordBatch) -> Result<BooleanArray, ArrowError> + Send + 'static,

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pub fn new(projection: ProjectionMask, f: F) -> Self

Create a new ArrowPredicateFn that invokes f on the columns specified in projection.

Trait Implementations§

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impl<F> ArrowPredicate for ArrowPredicateFn<F>
where F: FnMut(RecordBatch) -> Result<BooleanArray, ArrowError> + Send + 'static,

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fn projection(&self) -> &ProjectionMask

Returns the ProjectionMask that describes the columns required to evaluate this predicate. Read more
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fn evaluate(&mut self, batch: RecordBatch) -> Result<BooleanArray, ArrowError>

Evaluate this predicate for the given [RecordBatch] containing the columns identified by Self::projection Read more

Auto Trait Implementations§

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impl<F> Freeze for ArrowPredicateFn<F>
where F: Freeze,

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impl<F> RefUnwindSafe for ArrowPredicateFn<F>
where F: RefUnwindSafe,

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impl<F> Send for ArrowPredicateFn<F>
where F: Send,

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impl<F> Sync for ArrowPredicateFn<F>
where F: Sync,

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impl<F> Unpin for ArrowPredicateFn<F>
where F: Unpin,

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impl<F> UnwindSafe for ArrowPredicateFn<F>
where F: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where 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 T
where 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 T
where 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 T
where 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> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<T, U> TryFrom<U> for T
where 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 T
where 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<T> Allocation for T
where T: RefUnwindSafe + Send + Sync,

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impl<T> ErasedDestructor for T
where T: 'static,