Struct FilterBuilder 

pub struct FilterBuilder {
    filter: BooleanArray,
    count: Option<usize>,
    optimize: bool,
}

A builder to construct FilterPredicate

Fields

filter: BooleanArray

count: Option<usize>

optimize: bool

Implementations

impl FilterBuilder

pub fn new(filter: &BooleanArray) -> FilterBuilder

Create a new FilterBuilder that can be used to construct a FilterPredicate

pub unsafe fn with_count(self, count: usize) -> FilterBuilder

Set the number of rows that the filter selects, so that Self::build does not have to count them.

Callers that build a mask row by row, or derive it from a validity buffer with a cached null count, often already hold this number.

Safety

count must equal BooleanArray::true_count of the filter passed to Self::new: the number of true values that are not null.

Example

let values = Int32Array::from(vec![1, 2, 3, 4]);
let mask = BooleanArray::from(vec![Some(true), None, Some(true), Some(false)]);
// The null is not selected, so the mask selects two rows.
// SAFETY: the count matches the mask.
let predicate = unsafe { FilterBuilder::new(&mask).with_count(2) }.build();
assert_eq!(predicate.count(), 2);
let filtered = predicate.filter(&values).unwrap();
assert_eq!(filtered.as_ref(), &Int32Array::from(vec![1, 3]));

pub fn optimize(self) -> FilterBuilder

Compute an optimized representation of the provided filter mask in Self::build, so that it can be applied to an array more quickly.

When filtering multiple arrays (e.g. a RecordBatch or a StructArray with multiple fields), optimizing the filter can provide significant performance benefits.

However, optimization takes time and can have a larger memory footprint than the original mask, so it is often faster to filter a single array, without filter optimization.

pub fn is_optimize_beneficial(data_type: &DataType) -> bool

Determines if calling FilterBuilder::optimize is beneficial for the given type even when filtering just a single array.

See FilterBuilder::optimize for more details.

pub fn build(self) -> FilterPredicate

Construct the final FilterPredicate

Trait Implementations

impl Debug for FilterBuilder

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

Formats the value using the given formatter.