Struct parquet::arrow::arrow_reader::RowSelection

pub struct RowSelection { /* private fields */ }

RowSelection allows selecting or skipping a provided number of rows when scanning the parquet file.

This is applied prior to reading column data, and can therefore be used to skip IO to fetch data into memory

A typical use-case would be using the PageIndex to filter out rows that don’t satisfy a predicate

Example

use parquet::arrow::arrow_reader::{RowSelection, RowSelector};

let selectors = vec![
  RowSelector { row_count: 5, skip: true },
  RowSelector { row_count: 5, skip: false },
  RowSelector { row_count: 5, skip: false },
  RowSelector { row_count: 5, skip: true },
];

// Creating a selection will combine adjacent selectors
let selection: RowSelection = selectors.into();

let expected = vec![
  RowSelector { row_count: 5, skip: true },
  RowSelector { row_count: 10, skip: false },
  RowSelector { row_count: 5, skip: true },
];

let actual: Vec<RowSelector> = selection.into();
assert_eq!(actual, expected);

Implementations

impl RowSelection

pub fn from_filters(filters: &[BooleanArray]) -> Self

Creates a RowSelection from a slice of BooleanArray

Panic

Panics if any of the BooleanArray contain nulls

pub fn split_off(&mut self, row_count: usize) -> Self

Splits off the first row_count from this RowSelection

pub fn and_then(&self, other: &Self) -> Self

Given a RowSelection computed under self, returns the RowSelection representing their conjunction

For example:

self: NNNNNNNNNNNNYYYYYYYYYYYYYYYYYYYYYYNNNYYYYY other: YYYYYNNNNYYYYYYYYYYYYY YYNNN

returned: NNNNNNNNNNNNYYYYYNNNNYYYYYYYYYYYYYNNNYYNNN

Panics

Panics if other does not have a length equal to the number of rows selected by this RowSelection

pub fn intersection(&self, other: &Self) -> Self

Compute the intersection of two RowSelection For example: self: NNYYYYNNYYNYN other: NYNNNNNNY

returned: NNNNNNNNYYNYN

pub fn selects_any(&self) -> bool

Returns true if this RowSelection selects any rows

pub fn iter(&self) -> impl Iterator<Item = &RowSelector>

Returns an iterator over the RowSelectors for this RowSelection.

Trait Implementations

impl Clone for RowSelection

fn clone(&self) -> RowSelection

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for RowSelection

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

Formats the value using the given formatter.

impl Default for RowSelection

fn default() -> RowSelection

Returns the “default value” for a type.

impl From<RowSelection> for Vec<RowSelector>

fn from(r: RowSelection) -> Self

Converts to this type from the input type.

impl From<RowSelection> for VecDeque<RowSelector>

fn from(r: RowSelection) -> Self

Converts to this type from the input type.

impl From<Vec<RowSelector, Global>> for RowSelection

fn from(selectors: Vec<RowSelector>) -> Self

Converts to this type from the input type.

impl PartialEq<RowSelection> for RowSelection

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

This method tests for self and other values to be equal, and is used by ==.

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

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

impl Eq for RowSelection

impl StructuralEq for RowSelection

impl StructuralPartialEq for RowSelection