fix: don't push down volatile predicates in projection

datafusion/optimizer/src/push_down_filter.rs

@@ -15,13 +15,14 @@
 //! Push Down Filter optimizer rule ensures that filters are applied as early as possible in the plan
 
 use crate::optimizer::ApplyOrder;
-use crate::utils::{conjunction, split_conjunction};
+use crate::utils::{conjunction, split_conjunction, split_conjunction_owned};
 use crate::{utils, OptimizerConfig, OptimizerRule};
 use datafusion_common::tree_node::{Transformed, TreeNode, VisitRecursion};
 use datafusion_common::{
     internal_err, plan_datafusion_err, Column, DFSchema, DataFusionError, Result,
 };
 use datafusion_expr::expr::Alias;
+use datafusion_expr::Volatility;
 use datafusion_expr::{
     and,
     expr_rewriter::replace_col,
@@ -652,32 +653,60 @@ impl OptimizerRule for PushDownFilter {
                 child_plan.with_new_inputs(&[new_filter])?
             }
             LogicalPlan::Projection(projection) => {
-                // A projection is filter-commutable, but re-writes all predicate expressions
+                // A projection is filter-commutable if it do not contain volatile predicates or contain volatile
+                // predicates that are not used in the filter. However, we should re-writes all predicate expressions.
                 // collect projection.
-                let replace_map = projection
-                    .schema
-                    .fields()
-                    .iter()
-                    .enumerate()
-                    .map(|(i, field)| {
-                        // strip alias, as they should not be part of filters
-                        let expr = match &projection.expr[i] {
-                            Expr::Alias(Alias { expr, .. }) => expr.as_ref().clone(),
-                            expr => expr.clone(),
-                        };
-
-                        (field.qualified_name(), expr)
-                    })
-                    .collect::<HashMap<_, _>>();
+                let (volatile_map, non_volatile_map): (HashMap<_, _>, HashMap<_, _>) =
+                    projection
+                        .schema
+                        .fields()
+                        .iter()
+                        .enumerate()
+                        .map(|(i, field)| {
+                            // strip alias, as they should not be part of filters
+                            let expr = match &projection.expr[i] {
+                                Expr::Alias(Alias { expr, .. }) => expr.as_ref().clone(),
+                                expr => expr.clone(),
+                            };
+
+                            (field.qualified_name(), expr)
+                        })
+                        .partition(|(_, value)| is_volatile_expression(value.clone()));
 
-                // re-write all filters based on this projection
-                // E.g. in `Filter: b\n  Projection: a > 1 as b`, we can swap them, but the filter must be "a > 1"
-                let new_filter = LogicalPlan::Filter(Filter::try_new(
-                    replace_cols_by_name(filter.predicate.clone(), &replace_map)?,
-                    projection.input.clone(),
-                )?);
+                let mut push_predicates = vec![];
+                let mut keep_predicates = vec![];
+                for expr in split_conjunction_owned(filter.predicate.clone()).into_iter()
+                {
+                    if contain(expr.clone(), &volatile_map) {
+                        keep_predicates.push(expr);
+                    } else {
+                        push_predicates.push(expr);
+                    }
+                }
 
-                child_plan.with_new_inputs(&[new_filter])?
+                match conjunction(push_predicates) {
+                    Some(expr) => {
+                        // re-write all filters based on this projection
+                        // E.g. in `Filter: b\n  Projection: a > 1 as b`, we can swap them, but the filter must be "a > 1"
+                        let new_filter = LogicalPlan::Filter(Filter::try_new(
+                            replace_cols_by_name(expr, &non_volatile_map)?,
+                            projection.input.clone(),
+                        )?);
+
+                        match conjunction(keep_predicates) {
+                            None => child_plan.with_new_inputs(&[new_filter])?,
+                            Some(keep_predicate) => {
+                                let child_plan =
+                                    child_plan.with_new_inputs(&[new_filter])?;
+                                LogicalPlan::Filter(Filter::try_new(
+                                    keep_predicate,
+                                    Arc::new(child_plan),
+                                )?)
+                            }
+                        }
+                    }
+                    None => return Ok(None),
+                }
             }
             LogicalPlan::Union(union) => {
                 let mut inputs = Vec::with_capacity(union.inputs.len());
@@ -881,6 +910,42 @@ pub fn replace_cols_by_name(
     })
 }
 
+/// check whether the expression is volatile predicates
+pub fn is_volatile_expression(e: Expr) -> bool {
+    let mut is_volatile = false;
+    e.apply(&mut |expr| {
+        Ok(match expr {
+            Expr::ScalarFunction(f) if f.fun.volatility() == Volatility::Volatile => {
+                is_volatile = true;
+                VisitRecursion::Stop
+            }
+            _ => VisitRecursion::Continue,
+        })
+    })
+    .unwrap();
+    is_volatile
+}
+
+/// check whether the expression uses the columns in `check_map`.
+pub fn contain(e: Expr, check_map: &HashMap<String, Expr>) -> bool {
+    let mut is_contain = false;
+    e.apply(&mut |expr| {
+        Ok(if let Expr::Column(c) = &expr {
+            match check_map.get(&c.flat_name()) {
+                Some(_) => {
+                    is_contain = true;
+                    VisitRecursion::Stop
+                }
+                None => VisitRecursion::Continue,
+            }
+        } else {
+            VisitRecursion::Continue
+        })
+    })
+    .unwrap();
+    is_contain
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -893,9 +958,9 @@ mod tests {
     use datafusion_common::{DFSchema, DFSchemaRef};
     use datafusion_expr::logical_plan::table_scan;
     use datafusion_expr::{
-        and, col, in_list, in_subquery, lit, logical_plan::JoinType, or, sum, BinaryExpr,
-        Expr, Extension, LogicalPlanBuilder, Operator, TableSource, TableType,
-        UserDefinedLogicalNodeCore,
+        and, col, in_list, in_subquery, lit, logical_plan::JoinType, or, random, sum,
+        BinaryExpr, Expr, Extension, LogicalPlanBuilder, Operator, TableSource,
+        TableType, UserDefinedLogicalNodeCore,
     };
     use std::fmt::{Debug, Formatter};
     use std::sync::Arc;
@@ -2712,4 +2777,79 @@ Projection: a, b
         \n    TableScan: test2";
         assert_optimized_plan_eq(&plan, expected)
     }
+
+    #[test]
+    fn test_push_down_volatile_function_in_aggregate() -> Result<()> {
+        // SELECT t.a, t.r FROM (SELECT a, SUM(b), random()+1 AS r FROM test1 GROUP BY a) AS t WHERE t.a > 5 AND t.r > 0.5;
+        let table_scan = test_table_scan_with_name("test1")?;
+        let plan = LogicalPlanBuilder::from(table_scan)
+            .aggregate(vec![col("a")], vec![sum(col("b"))])?
+            .project(vec![
+                col("a"),
+                sum(col("b")),
+                add(random(), lit(1)).alias("r"),
+            ])?
+            .alias("t")?
+            .filter(col("t.a").gt(lit(5)).and(col("t.r").gt(lit(0.5))))?
+            .project(vec![col("t.a"), col("t.r")])?
+            .build()?;
+
+        let expected_before = "Projection: t.a, t.r\
+        \n  Filter: t.a > Int32(5) AND t.r > Float64(0.5)\
+        \n    SubqueryAlias: t\
+        \n      Projection: test1.a, SUM(test1.b), random() + Int32(1) AS r\
+        \n        Aggregate: groupBy=[[test1.a]], aggr=[[SUM(test1.b)]]\
+        \n          TableScan: test1";
+        assert_eq!(format!("{plan:?}"), expected_before);
+
+        let expected_after = "Projection: t.a, t.r\
+        \n  SubqueryAlias: t\
+        \n    Filter: r > Float64(0.5)\
+        \n      Projection: test1.a, SUM(test1.b), random() + Int32(1) AS r\
+        \n        Aggregate: groupBy=[[test1.a]], aggr=[[SUM(test1.b)]]\
+        \n          TableScan: test1, full_filters=[test1.a > Int32(5)]";
+        assert_optimized_plan_eq(&plan, expected_after)
+    }
+
+    #[test]
+    fn test_push_down_volatile_function_in_join() -> Result<()> {
+        // SELECT t.a, t.r FROM (SELECT test1.a AS a, random() AS r FROM test1 join test2 ON test1.a = test2.a) AS t WHERE t.r > 0.5;
+        let table_scan = test_table_scan_with_name("test1")?;
+        let left = LogicalPlanBuilder::from(table_scan).build()?;
+        let right_table_scan = test_table_scan_with_name("test2")?;
+        let right = LogicalPlanBuilder::from(right_table_scan).build()?;
+        let plan = LogicalPlanBuilder::from(left)
+            .join(
+                right,
+                JoinType::Inner,
+                (
+                    vec![Column::from_qualified_name("test1.a")],
+                    vec![Column::from_qualified_name("test2.a")],
+                ),
+                None,
+            )?
+            .project(vec![col("test1.a").alias("a"), random().alias("r")])?
+            .alias("t")?
+            .filter(col("t.r").gt(lit(0.8)))?
+            .project(vec![col("t.a"), col("t.r")])?
+            .build()?;
+
+        let expected_before = "Projection: t.a, t.r\
+        \n  Filter: t.r > Float64(0.8)\
+        \n    SubqueryAlias: t\
+        \n      Projection: test1.a AS a, random() AS r\
+        \n        Inner Join: test1.a = test2.a\
+        \n          TableScan: test1\
+        \n          TableScan: test2";
+        assert_eq!(format!("{plan:?}"), expected_before);
+
+        let expected = "Projection: t.a, t.r\
+        \n  SubqueryAlias: t\
+        \n    Filter: r > Float64(0.8)\
+        \n      Projection: test1.a AS a, random() AS r\
+        \n        Inner Join: test1.a = test2.a\
+        \n          TableScan: test1\
+        \n          TableScan: test2";
+        assert_optimized_plan_eq(&plan, expected)
+    }
 }