thinkharderdev commented on code in PR #2335: URL: https://github.com/apache/arrow-rs/pull/2335#discussion_r939108683
########## parquet/src/arrow/arrow_reader/filter.rs: ########## @@ -0,0 +1,95 @@ +// 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::arrow::ProjectionMask; +use arrow::array::BooleanArray; +use arrow::error::Result as ArrowResult; +use arrow::record_batch::RecordBatch; + +/// A predicate operating on [`RecordBatch`] +pub trait ArrowPredicate: Send + 'static { + /// Returns the projection mask for this predicate + fn projection(&self) -> &ProjectionMask; + + /// Called with a [`RecordBatch`] containing the columns identified by [`Self::mask`], + /// with `true` values in the returned [`BooleanArray`] indicating rows + /// matching the predicate. + /// + /// The returned [`BooleanArray`] must not contain any nulls + fn filter(&mut self, batch: RecordBatch) -> ArrowResult<BooleanArray>; +} + +/// An [`ArrowPredicate`] created from an [`FnMut`] +pub struct ArrowPredicateFn<F> { + f: F, + projection: ProjectionMask, +} + +impl<F> ArrowPredicateFn<F> +where + F: FnMut(RecordBatch) -> ArrowResult<BooleanArray> + Send + 'static, +{ + /// Create a new [`ArrowPredicateFn`] + pub fn new(projection: ProjectionMask, f: F) -> Self { + Self { f, projection } + } +} + +impl<F> ArrowPredicate for ArrowPredicateFn<F> +where + F: FnMut(RecordBatch) -> ArrowResult<BooleanArray> + Send + 'static, +{ + fn projection(&self) -> &ProjectionMask { + &self.projection + } + + fn filter(&mut self, batch: RecordBatch) -> ArrowResult<BooleanArray> { + (self.f)(batch) + } +} + +/// A [`RowFilter`] allows pushing down a filter predicate to skip IO and decode +/// +/// This consists of a list of [`ArrowPredicate`] where only the rows that satisfy all +/// of the predicates will be returned. Any [`RowSelection`] will be applied prior +/// to the first predicate, and each predicate in turn will then be used to compute +/// a more refined [`RowSelection`] to use when evaluating the subsequent predicates. +/// +/// Once all predicates have been evaluated, the resulting [`RowSelection`] will be +/// used to return just the desired rows. +/// +/// This design has a couple of implications: Review Comment: Nice, I like this -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
