Jimexist commented on a change in pull request #1141: URL: https://github.com/apache/arrow-datafusion/pull/1141#discussion_r740232427
########## File path: datafusion/src/datasource/listing/helpers.rs ########## @@ -0,0 +1,722 @@ +// 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. + +//! Helper functions for the table implementation + +use std::sync::Arc; + +use arrow::{ + array::{ + Array, ArrayBuilder, ArrayRef, Date64Array, Date64Builder, StringArray, + StringBuilder, UInt64Array, UInt64Builder, + }, + datatypes::{DataType, Field, Schema}, + record_batch::RecordBatch, +}; +use chrono::{TimeZone, Utc}; +use futures::{ + stream::{self}, + StreamExt, TryStreamExt, +}; +use log::debug; + +use crate::{ + error::Result, + execution::context::ExecutionContext, + logical_plan::{self, Expr, ExpressionVisitor, Recursion}, + physical_plan::functions::Volatility, + scalar::ScalarValue, +}; + +use crate::datasource::{ + object_store::{FileMeta, ObjectStore, SizedFile}, + MemTable, PartitionedFile, PartitionedFileStream, +}; + +const FILE_SIZE_COLUMN_NAME: &str = "_df_part_file_size_"; +const FILE_PATH_COLUMN_NAME: &str = "_df_part_file_path_"; +const FILE_MODIFIED_COLUMN_NAME: &str = "_df_part_file_modified_"; + +/// The `ExpressionVisitor` for `expr_applicable_for_cols`. Walks the tree to +/// validate that the given expression is applicable with only the `col_names` +/// set of columns. +struct ApplicabilityVisitor<'a> { + col_names: &'a [String], + is_applicable: &'a mut bool, +} + +impl ApplicabilityVisitor<'_> { + fn visit_volatility(self, volatility: Volatility) -> Recursion<Self> { + match volatility { + Volatility::Immutable => Recursion::Continue(self), + // TODO: Stable functions could be `applicable`, but that would require access to the context + Volatility::Stable | Volatility::Volatile => { + *self.is_applicable = false; + Recursion::Stop(self) + } + } + } +} + +impl ExpressionVisitor for ApplicabilityVisitor<'_> { + fn pre_visit(self, expr: &Expr) -> Result<Recursion<Self>> { + let rec = match expr { + Expr::Column(logical_plan::Column { ref name, .. }) => { + *self.is_applicable &= self.col_names.contains(name); + Recursion::Stop(self) // leaf node anyway + } + Expr::Literal(_) + | Expr::Alias(_, _) + | Expr::ScalarVariable(_) + | Expr::Not(_) + | Expr::IsNotNull(_) + | Expr::IsNull(_) + | Expr::Negative(_) + | Expr::Cast { .. } + | Expr::TryCast { .. } + | Expr::BinaryExpr { .. } + | Expr::Between { .. } + | Expr::InList { .. } + | Expr::GetIndexedField { .. } + | Expr::Case { .. } => Recursion::Continue(self), + + Expr::ScalarFunction { fun, .. } => self.visit_volatility(fun.volatility()), + Expr::ScalarUDF { fun, .. } => { + self.visit_volatility(fun.signature.volatility) + } + + // TODO other expressions are not handled yet: + // - AGGREGATE, WINDOW and SORT should not end up in filter conditions, except maybe in some edge cases + // - Can `Wildcard` be considered as a `Literal`? + // - ScalarVariable could be `applicable`, but that would require access to the context + Expr::AggregateUDF { .. } + | Expr::AggregateFunction { .. } + | Expr::Sort { .. } + | Expr::WindowFunction { .. } + | Expr::Wildcard => { + *self.is_applicable = false; + Recursion::Stop(self) + } + }; + Ok(rec) + } +} + +/// Check whether the given expression can be resolved using only the columns `col_names`. +/// This means that if this function returns true: +/// - the table provider can filter the table partition values with this expression +/// - the expression can be marked as `TableProviderFilterPushDown::Exact` once this filtering +/// was performed +pub fn expr_applicable_for_cols(col_names: &[String], expr: &Expr) -> bool { + let mut is_applicable = true; + expr.accept(ApplicabilityVisitor { + col_names, + is_applicable: &mut is_applicable, + }) + .unwrap(); + is_applicable +} + +/// Partition the list of files into `n` groups +pub fn split_files( + partitioned_files: Vec<PartitionedFile>, + n: usize, +) -> Vec<Vec<PartitionedFile>> { + if partitioned_files.is_empty() { + return vec![]; + } + let chunk_size = (partitioned_files.len() + n - 1) / n; Review comment: ```suggestion // effectively this is div with rounding up instead of truncating let chunk_size = (partitioned_files.len() + n - 1) / n; ``` -- This is an automated message from the Apache Git Service. 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