viirya commented on code in PR #1791: URL: https://github.com/apache/arrow-rs/pull/1791#discussion_r889658333
########## parquet/src/file/page_index/range.rs: ########## @@ -0,0 +1,474 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. +use crate::errors::ParquetError; +use parquet_format::PageLocation; +use std::cmp::Ordering; +use std::collections::VecDeque; + +/// A row range +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +pub struct Range { + /// Its start + pub from: usize, + /// Its end + pub to: usize, +} + +impl Range { + // Creates a range of [from, to] (from and to are both inclusive) + pub fn new(from: usize, to: usize) -> Self { + assert!(from <= to); + Self { from, to } + } + + pub fn count(&self) -> usize { + self.to - self.from + 1 + } + + pub fn is_before(&self, other: &Range) -> bool { + self.to < other.from + } + + pub fn is_after(&self, other: &Range) -> bool { + self.from > other.to + } + + /// Return the union of the two ranges, + /// Return `None` if there are hole between them. + pub fn union(left: &Range, right: &Range) -> Option<Range> { + if left.from <= right.from { + if left.to + 1 >= right.from { + return Some(Range { + from: left.from, + to: std::cmp::max(left.to, right.to), + }); + } + } else if right.to + 1 >= left.from { + return Some(Range { + from: right.from, + to: std::cmp::max(left.to, right.to), + }); + } + None + } + + /// Returns the intersection of the two ranges, + /// return null if they are not overlapped. + pub fn intersection(left: &Range, right: &Range) -> Option<Range> { + if left.from <= right.from { + if left.to >= right.from { + return Some(Range { + from: right.from, + to: std::cmp::min(left.to, right.to), + }); + } + } else if right.to >= left.from { + return Some(Range { + from: left.from, + to: std::cmp::min(left.to, right.to), + }); + } + None + } +} + +/// Struct representing row ranges in a row-group. These row ranges are calculated as a result of using +/// the column index on the filtering. +#[derive(Debug, Clone)] +pub struct RowRanges { + pub ranges: VecDeque<Range>, +} + +impl RowRanges { + //create an empty RowRanges + pub fn new_empty() -> Self { + RowRanges { + ranges: VecDeque::new(), + } + } + + pub fn count(&self) -> usize { + self.ranges.len() + } + + pub fn filter_with_mask(&self, mask: &[bool]) -> Result<RowRanges, ParquetError> { + if self.ranges.len() != mask.len() { + return Err(ParquetError::General(format!( + "Mask size {} is not equal to number of pages {}", + mask.len(), + self.count() + ))); + } + let vec_range = mask + .iter() + .zip(self.ranges.clone()) + .filter_map(|(&f, r)| if f { Some(r) } else { None }) + .collect(); + Ok(RowRanges { ranges: vec_range }) + } + + //Add a range to the end of the list of ranges. It maintains the disjunctive ascending order of the ranges by + //trying to union the specified range to the last ranges in the list. The specified range shall be larger than + //the last one or might be overlapped with some of the last ones. + // [a, b] < [c, d] if b < c + pub fn add(&mut self, range: Range) { + let mut to_add = range; + let count = self.count(); + if count > 0 { + for i in 1..(count + 1) { + let index = count - i; + let last = self.ranges.get(index).unwrap(); + assert!(!last.is_after(&range), "Must add range in ascending!"); + // try to merge range + match Range::union(last, &to_add) { + None => { + break; + } + Some(r) => { + to_add = r; + self.ranges.remove(index); + } + } + } + } + self.ranges.push_back(to_add); + } + + /// Calculates the union of the two specified RowRanges object. The union of two range is calculated if there are no + /// elements between them. Otherwise, the two disjunctive ranges are stored separately. + /// For example: + /// [113, 241] ∪ [221, 340] = [113, 330] + /// [113, 230] ∪ [231, 340] = [113, 340] + /// while + /// [113, 230] ∪ [232, 340] = [113, 230], [232, 340] + /// + /// The result RowRanges object will contain all the row indexes that were contained in one of the specified objects. + pub fn union(mut left: RowRanges, mut right: RowRanges) -> RowRanges { + let v1 = &mut left.ranges; + let v2 = &mut right.ranges; + let mut result = RowRanges::new_empty(); + if v2.is_empty() { + left.clone() + } else { + let mut range2 = v2.pop_front().unwrap(); + while !v1.is_empty() { + let range1 = v1.pop_front().unwrap(); + if range1.is_after(&range2) { + result.add(range2); + range2 = range1; + std::mem::swap(v1, v2); + } else { + result.add(range1); + } + } + + result.add(range2); + while !v2.is_empty() { + result.add(v2.pop_front().unwrap()) + } + + result + } + } + + /// Calculates the intersection of the two specified RowRanges object. Two ranges intersect if they have common + /// elements otherwise the result is empty. + /// For example: + /// [113, 241] ∩ [221, 340] = [221, 241] + /// while + /// [113, 230] ∩ [231, 340] = <EMPTY> + /// + /// The result RowRanges object will contain all the row indexes there were contained in both of the specified objects + #[allow(clippy::mut_range_bound)] + pub fn intersection(left: RowRanges, right: RowRanges) -> RowRanges { + let mut result = RowRanges::new_empty(); + let mut right_index = 0; + for l in left.ranges.iter() { + for i in right_index..right.ranges.len() { + let r = right.ranges.get(i).unwrap(); + if l.is_before(r) { + break; + } else if l.is_after(r) { + right_index = i + 1; + continue; + } + if let Some(ra) = Range::intersection(l, r) { + result.add(ra); + } + } + } + result + } + + pub fn row_count(&self) -> usize { + self.ranges.iter().map(|x| x.count()).sum() + } + + pub fn is_overlapping(&self, x: &Range) -> bool { + self.ranges + .binary_search_by(|y| -> Ordering { + if y.is_before(x) { + Ordering::Less + } else if y.is_after(x) { + Ordering::Greater + } else { + Ordering::Equal + } + }) + .is_ok() + } +} + +/// Return the row ranges `Vec(start, len)` of all the selected pages Review Comment: This doesn't return `Vec(start, len)` actually. It reads to confusing. You may document it returning `RowRanges` which represents a sequence of ranges of all the selected pages. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
