alamb commented on a change in pull request #9309: URL: https://github.com/apache/arrow/pull/9309#discussion_r577103996
########## File path: rust/datafusion/src/optimizer/constant_folding.rs ########## @@ -0,0 +1,671 @@ +// 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. + +//! Boolean comparision rule rewrites redudant comparison expression involing boolean literal into +//! unary expression. + +use std::sync::Arc; + +use arrow::datatypes::DataType; + +use crate::error::Result; +use crate::logical_plan::{DFSchemaRef, Expr, LogicalPlan, Operator}; +use crate::optimizer::optimizer::OptimizerRule; +use crate::optimizer::utils; +use crate::scalar::ScalarValue; + +/// Optimizer that simplifies comparison expressions involving boolean literals. +/// +/// Recursively go through all expressionss and simplify the following cases: +/// * `expr = true` and `expr != false` to `expr` when `expr` is of boolean type +/// * `expr = false` and `expr != true` to `!expr` when `expr` is of boolean type +/// * `true = true` and `false = false` to `true` +/// * `false = true` and `true = false` to `false` +/// * `!!expr` to `expr` +/// * `expr = null` and `expr != null` to `null` +pub struct ConstantFolding {} + +impl ConstantFolding { + #[allow(missing_docs)] + pub fn new() -> Self { + Self {} + } +} + +impl OptimizerRule for ConstantFolding { + fn optimize(&self, plan: &LogicalPlan) -> Result<LogicalPlan> { + // We need to pass down the all schemas within the plan tree to `optimize_expr` in order to + // to evaluate expression types. For example, a projection plan's schema will only include + // projected columns. With just the projected schema, it's not possible to infer types for + // expressions that references non-projected columns within the same project plan or its + // children plans. + + match plan { + LogicalPlan::Filter { predicate, input } => Ok(LogicalPlan::Filter { + predicate: optimize_expr(predicate, &plan.all_schemas())?, + input: Arc::new(self.optimize(input)?), + }), + // Rest: recurse into plan, apply optimization where possible + LogicalPlan::Projection { .. } + | LogicalPlan::Aggregate { .. } + | LogicalPlan::Repartition { .. } + | LogicalPlan::CreateExternalTable { .. } + | LogicalPlan::Extension { .. } + | LogicalPlan::Sort { .. } + | LogicalPlan::Explain { .. } + | LogicalPlan::Limit { .. } + | LogicalPlan::Join { .. } => { + // apply the optimization to all inputs of the plan + let inputs = utils::inputs(plan); + let new_inputs = inputs + .iter() + .map(|plan| self.optimize(plan)) + .collect::<Result<Vec<_>>>()?; + + let schemas = plan.all_schemas(); + let expr = utils::expressions(plan) + .iter() + .map(|e| optimize_expr(e, &schemas)) + .collect::<Result<Vec<_>>>()?; + + utils::from_plan(plan, &expr, &new_inputs) + } + LogicalPlan::TableScan { .. } | LogicalPlan::EmptyRelation { .. } => { + Ok(plan.clone()) + } + } + } + + fn name(&self) -> &str { + "constant_folding" + } +} + +fn is_boolean_type(expr: &Expr, schemas: &[&DFSchemaRef]) -> bool { + for schema in schemas { + if let Ok(DataType::Boolean) = expr.get_type(schema) { + return true; + } + } + + false +} + +/// Recursively transverses the expression tree. +fn optimize_expr(e: &Expr, schemas: &[&DFSchemaRef]) -> Result<Expr> { + Ok(match e { + Expr::BinaryExpr { left, op, right } => { + let left = optimize_expr(left, schemas)?; + let right = optimize_expr(right, schemas)?; + match op { + Operator::Eq => match (&left, &right) { + ( + Expr::Literal(ScalarValue::Boolean(l)), + Expr::Literal(ScalarValue::Boolean(r)), + ) => match (l, r) { + (Some(l), Some(r)) => { + Expr::Literal(ScalarValue::Boolean(Some(l == r))) + } + _ => Expr::Literal(ScalarValue::Boolean(None)), + }, + (Expr::Literal(ScalarValue::Boolean(b)), _) + if is_boolean_type(&right, schemas) => + { + match b { + Some(true) => right, + Some(false) => Expr::Not(Box::new(right)), + None => Expr::Literal(ScalarValue::Boolean(None)), + } + } + (_, Expr::Literal(ScalarValue::Boolean(b))) + if is_boolean_type(&left, schemas) => + { + match b { + Some(true) => left, + Some(false) => Expr::Not(Box::new(left)), + None => Expr::Literal(ScalarValue::Boolean(None)), + } + } + _ => Expr::BinaryExpr { + left: Box::new(left), + op: Operator::Eq, + right: Box::new(right), + }, + }, + Operator::NotEq => match (&left, &right) { + ( + Expr::Literal(ScalarValue::Boolean(l)), + Expr::Literal(ScalarValue::Boolean(r)), + ) => match (l, r) { + (Some(l), Some(r)) => { + Expr::Literal(ScalarValue::Boolean(Some(l != r))) + } + _ => Expr::Literal(ScalarValue::Boolean(None)), + }, + (Expr::Literal(ScalarValue::Boolean(b)), _) + if is_boolean_type(&right, schemas) => + { + match b { + Some(true) => Expr::Not(Box::new(right)), + Some(false) => right, + None => Expr::Literal(ScalarValue::Boolean(None)), + } + } + (_, Expr::Literal(ScalarValue::Boolean(b))) + if is_boolean_type(&left, schemas) => + { + match b { + Some(true) => Expr::Not(Box::new(left)), + Some(false) => left, + None => Expr::Literal(ScalarValue::Boolean(None)), + } + } + _ => Expr::BinaryExpr { + left: Box::new(left), + op: Operator::NotEq, + right: Box::new(right), + }, + }, + _ => Expr::BinaryExpr { + left: Box::new(left), + op: *op, + right: Box::new(right), + }, + } + } + Expr::Not(expr) => match &**expr { + Expr::Not(inner) => optimize_expr(&inner, schemas)?, + _ => Expr::Not(Box::new(optimize_expr(&expr, schemas)?)), + }, + Expr::Case { + expr, + when_then_expr, + else_expr, + } => { + // recurse into CASE WHEN condition expressions Review comment: 👍 ########## File path: rust/datafusion/src/optimizer/constant_folding.rs ########## @@ -0,0 +1,671 @@ +// 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. + +//! Boolean comparision rule rewrites redudant comparison expression involing boolean literal into +//! unary expression. + +use std::sync::Arc; + +use arrow::datatypes::DataType; + +use crate::error::Result; +use crate::logical_plan::{DFSchemaRef, Expr, LogicalPlan, Operator}; +use crate::optimizer::optimizer::OptimizerRule; +use crate::optimizer::utils; +use crate::scalar::ScalarValue; + +/// Optimizer that simplifies comparison expressions involving boolean literals. +/// +/// Recursively go through all expressionss and simplify the following cases: +/// * `expr = true` and `expr != false` to `expr` when `expr` is of boolean type +/// * `expr = false` and `expr != true` to `!expr` when `expr` is of boolean type +/// * `true = true` and `false = false` to `true` +/// * `false = true` and `true = false` to `false` +/// * `!!expr` to `expr` +/// * `expr = null` and `expr != null` to `null` +pub struct ConstantFolding {} + +impl ConstantFolding { + #[allow(missing_docs)] + pub fn new() -> Self { + Self {} + } +} + +impl OptimizerRule for ConstantFolding { + fn optimize(&self, plan: &LogicalPlan) -> Result<LogicalPlan> { + // We need to pass down the all schemas within the plan tree to `optimize_expr` in order to + // to evaluate expression types. For example, a projection plan's schema will only include + // projected columns. With just the projected schema, it's not possible to infer types for + // expressions that references non-projected columns within the same project plan or its + // children plans. + + match plan { + LogicalPlan::Filter { predicate, input } => Ok(LogicalPlan::Filter { + predicate: optimize_expr(predicate, &plan.all_schemas())?, + input: Arc::new(self.optimize(input)?), + }), + // Rest: recurse into plan, apply optimization where possible + LogicalPlan::Projection { .. } + | LogicalPlan::Aggregate { .. } + | LogicalPlan::Repartition { .. } + | LogicalPlan::CreateExternalTable { .. } + | LogicalPlan::Extension { .. } + | LogicalPlan::Sort { .. } + | LogicalPlan::Explain { .. } + | LogicalPlan::Limit { .. } + | LogicalPlan::Join { .. } => { + // apply the optimization to all inputs of the plan + let inputs = utils::inputs(plan); + let new_inputs = inputs + .iter() + .map(|plan| self.optimize(plan)) + .collect::<Result<Vec<_>>>()?; + + let schemas = plan.all_schemas(); + let expr = utils::expressions(plan) + .iter() + .map(|e| optimize_expr(e, &schemas)) + .collect::<Result<Vec<_>>>()?; + + utils::from_plan(plan, &expr, &new_inputs) + } + LogicalPlan::TableScan { .. } | LogicalPlan::EmptyRelation { .. } => { + Ok(plan.clone()) + } + } + } + + fn name(&self) -> &str { + "constant_folding" + } +} + +fn is_boolean_type(expr: &Expr, schemas: &[&DFSchemaRef]) -> bool { + for schema in schemas { + if let Ok(DataType::Boolean) = expr.get_type(schema) { + return true; + } + } + + false +} + +/// Recursively transverses the expression tree. +fn optimize_expr(e: &Expr, schemas: &[&DFSchemaRef]) -> Result<Expr> { + Ok(match e { + Expr::BinaryExpr { left, op, right } => { + let left = optimize_expr(left, schemas)?; + let right = optimize_expr(right, schemas)?; + match op { + Operator::Eq => match (&left, &right) { + ( + Expr::Literal(ScalarValue::Boolean(l)), + Expr::Literal(ScalarValue::Boolean(r)), + ) => match (l, r) { + (Some(l), Some(r)) => { + Expr::Literal(ScalarValue::Boolean(Some(l == r))) + } + _ => Expr::Literal(ScalarValue::Boolean(None)), + }, + (Expr::Literal(ScalarValue::Boolean(b)), _) + if is_boolean_type(&right, schemas) => + { + match b { + Some(true) => right, + Some(false) => Expr::Not(Box::new(right)), + None => Expr::Literal(ScalarValue::Boolean(None)), + } + } + (_, Expr::Literal(ScalarValue::Boolean(b))) + if is_boolean_type(&left, schemas) => + { + match b { + Some(true) => left, + Some(false) => Expr::Not(Box::new(left)), + None => Expr::Literal(ScalarValue::Boolean(None)), + } + } + _ => Expr::BinaryExpr { + left: Box::new(left), + op: Operator::Eq, + right: Box::new(right), + }, + }, + Operator::NotEq => match (&left, &right) { + ( + Expr::Literal(ScalarValue::Boolean(l)), + Expr::Literal(ScalarValue::Boolean(r)), + ) => match (l, r) { + (Some(l), Some(r)) => { + Expr::Literal(ScalarValue::Boolean(Some(l != r))) + } + _ => Expr::Literal(ScalarValue::Boolean(None)), + }, + (Expr::Literal(ScalarValue::Boolean(b)), _) + if is_boolean_type(&right, schemas) => + { + match b { + Some(true) => Expr::Not(Box::new(right)), + Some(false) => right, + None => Expr::Literal(ScalarValue::Boolean(None)), + } + } + (_, Expr::Literal(ScalarValue::Boolean(b))) + if is_boolean_type(&left, schemas) => + { + match b { + Some(true) => Expr::Not(Box::new(left)), + Some(false) => left, + None => Expr::Literal(ScalarValue::Boolean(None)), + } + } + _ => Expr::BinaryExpr { + left: Box::new(left), + op: Operator::NotEq, + right: Box::new(right), + }, + }, + _ => Expr::BinaryExpr { + left: Box::new(left), + op: *op, + right: Box::new(right), + }, + } + } + Expr::Not(expr) => match &**expr { + Expr::Not(inner) => optimize_expr(&inner, schemas)?, + _ => Expr::Not(Box::new(optimize_expr(&expr, schemas)?)), + }, + Expr::Case { + expr, + when_then_expr, + else_expr, + } => { + // recurse into CASE WHEN condition expressions + Expr::Case { + expr: match expr { + Some(e) => Some(Box::new(optimize_expr(e, schemas)?)), + None => None, + }, + when_then_expr: when_then_expr + .iter() + .map(|(when, then)| { + Ok(( + Box::new(optimize_expr(when, schemas)?), + Box::new(optimize_expr(then, schemas)?), + )) + }) + .collect::<Result<_>>()?, + else_expr: match else_expr { + Some(e) => Some(Box::new(optimize_expr(e, schemas)?)), + None => None, + }, + } + } + Expr::Alias(expr, name) => { + Expr::Alias(Box::new(optimize_expr(expr, schemas)?), name.clone()) + } + Expr::Negative(expr) => Expr::Negative(Box::new(optimize_expr(expr, schemas)?)), + Expr::InList { + expr, + list, + negated, + } => Expr::InList { + expr: Box::new(optimize_expr(expr, schemas)?), + list: list + .iter() + .map(|e| optimize_expr(e, schemas)) + .collect::<Result<_>>()?, + negated: *negated, + }, + Expr::IsNotNull(expr) => Expr::IsNotNull(Box::new(optimize_expr(expr, schemas)?)), + Expr::IsNull(expr) => Expr::IsNull(Box::new(optimize_expr(expr, schemas)?)), + Expr::Cast { expr, data_type } => Expr::Cast { + expr: Box::new(optimize_expr(expr, schemas)?), + data_type: data_type.clone(), + }, + Expr::Between { + expr, + negated, + low, + high, + } => Expr::Between { + expr: Box::new(optimize_expr(expr, schemas)?), + negated: *negated, + low: Box::new(optimize_expr(low, schemas)?), + high: Box::new(optimize_expr(high, schemas)?), + }, + Expr::ScalarFunction { fun, args } => Expr::ScalarFunction { + fun: fun.clone(), + args: args + .iter() + .map(|e| optimize_expr(e, schemas)) + .collect::<Result<_>>()?, + }, + Expr::ScalarUDF { fun, args } => Expr::ScalarUDF { + fun: fun.clone(), + args: args + .iter() + .map(|e| optimize_expr(e, schemas)) + .collect::<Result<_>>()?, + }, + Expr::AggregateFunction { + fun, + args, + distinct, + } => Expr::AggregateFunction { + fun: fun.clone(), + args: args + .iter() + .map(|e| optimize_expr(e, schemas)) + .collect::<Result<_>>()?, + distinct: *distinct, + }, + Expr::AggregateUDF { fun, args } => Expr::AggregateUDF { + fun: fun.clone(), + args: args + .iter() + .map(|e| optimize_expr(e, schemas)) + .collect::<Result<_>>()?, + }, + Expr::Sort { + expr, + asc, + nulls_first, + } => Expr::Sort { + expr: Box::new(optimize_expr(expr, schemas)?), + asc: *asc, + nulls_first: *nulls_first, + }, + Expr::Column { .. } + | Expr::ScalarVariable { .. } + | Expr::Literal { .. } + | Expr::Wildcard => e.clone(), + }) +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::logical_plan::{ + col, lit, max, min, DFField, DFSchema, LogicalPlanBuilder, + }; + + use arrow::datatypes::*; + + fn test_table_scan() -> Result<LogicalPlan> { + let schema = Schema::new(vec![ + Field::new("a", DataType::Boolean, false), + Field::new("b", DataType::Boolean, false), + Field::new("c", DataType::Boolean, false), + Field::new("d", DataType::UInt32, false), + ]); + LogicalPlanBuilder::scan_empty("test", &schema, None)?.build() + } + + fn expr_test_schema() -> DFSchemaRef { + Arc::new( + DFSchema::new(vec![ + DFField::new(None, "c1", DataType::Utf8, true), + DFField::new(None, "c2", DataType::Boolean, true), + ]) + .unwrap(), + ) + } + + #[test] + fn optimize_expr_not_not() -> Result<()> { + let schema = expr_test_schema(); + assert_eq!( + optimize_expr(&col("c2").not().not().not(), &[&schema])?, + col("c2").not(), + ); + + Ok(()) + } + + #[test] + fn optimize_expr_null_comparision() -> Result<()> { + let schema = expr_test_schema(); + + // x = null is always null + assert_eq!( Review comment: These tests are so much nicer to read ❤️ ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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