asolimando commented on code in PR #21122: URL: https://github.com/apache/datafusion/pull/21122#discussion_r3051939949
########## datafusion/physical-expr/src/expression_analyzer/default.rs: ########## @@ -0,0 +1,300 @@ +// 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. + +//! Default expression analyzer with Selinger-style estimation. + +use std::sync::Arc; + +use datafusion_common::{ColumnStatistics, ScalarValue, Statistics}; +use datafusion_expr::Operator; + +use crate::PhysicalExpr; +use crate::expressions::{BinaryExpr, Column, Literal, NotExpr}; + +use super::{AnalysisResult, ExpressionAnalyzer, ExpressionAnalyzerRegistry}; + +/// Default expression analyzer with Selinger-style estimation. +/// +/// Handles common expression types: +/// - Column references (uses column statistics) +/// - Binary expressions (AND, OR, comparison operators) +/// - Literals (constant selectivity/NDV) +/// - NOT expressions (1 - child selectivity) +#[derive(Debug, Default, Clone)] +pub struct DefaultExpressionAnalyzer; + +impl DefaultExpressionAnalyzer { + /// Get column index from a Column expression + fn get_column_index(expr: &Arc<dyn PhysicalExpr>) -> Option<usize> { + expr.as_any().downcast_ref::<Column>().map(|c| c.index()) + } + + /// Get column statistics for an expression if it's a column reference + fn get_column_stats<'a>( + expr: &Arc<dyn PhysicalExpr>, + input_stats: &'a Statistics, + ) -> Option<&'a ColumnStatistics> { + Self::get_column_index(expr) + .and_then(|idx| input_stats.column_statistics.get(idx)) + } + + /// Resolve NDV for a binary expression: try direct column stats first, + /// then fall back to the registry for arbitrary expressions + fn resolve_ndv( + left: &Arc<dyn PhysicalExpr>, + right: &Arc<dyn PhysicalExpr>, + input_stats: &Statistics, + registry: &ExpressionAnalyzerRegistry, + ) -> Option<usize> { + Self::get_column_stats(left, input_stats) Review Comment: You are right, I have fixed it in 25e473ad and added some extra tests. While fixing this, I have also simplified the code, using `registry.get_distinct_count` on each side with `max` to cover all cases, "expr-expr, expr-col and col-expr" which are now all fully symmetric, thanks! -- 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] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
