disallow pushdown of volatile functions (apache#16861)

* dissallow pushdown of volatile PhysicalExprs

* fix

* add FilteredVec helper to handle filter / remap pattern (#34)

* checkpoint: Address PR feedback in https://github.com/apach...

* add FilteredVec to consolidate handling of filter / remap pattern

* lint

* Add slt test for pushing volatile predicates down (#35)

---------

Co-authored-by: Andrew Lamb <[email protected]>

Author: adriangb

datafusion/core/tests/physical_optimizer/filter_pushdown/mod.rs

@@ -34,8 +34,12 @@ use datafusion::{
 };
 use datafusion_common::config::ConfigOptions;
 use datafusion_execution::object_store::ObjectStoreUrl;
+use datafusion_expr::ScalarUDF;
+use datafusion_functions::math::random::RandomFunc;
 use datafusion_functions_aggregate::count::count_udaf;
-use datafusion_physical_expr::{aggregate::AggregateExprBuilder, Partitioning};
+use datafusion_physical_expr::{
+    aggregate::AggregateExprBuilder, Partitioning, ScalarFunctionExpr,
+};
 use datafusion_physical_expr::{expressions::col, LexOrdering, PhysicalSortExpr};
 use datafusion_physical_optimizer::{
     filter_pushdown::FilterPushdown, PhysicalOptimizerRule,
@@ -76,6 +80,40 @@ fn test_pushdown_into_scan() {
     );
 }
 
+#[test]
+fn test_pushdown_volatile_functions_not_allowed() {
+    // Test that we do not push down filters with volatile functions
+    // Use random() as an example of a volatile function
+    let scan = TestScanBuilder::new(schema()).with_support(true).build();
+    let predicate = Arc::new(BinaryExpr::new(
+        Arc::new(Column::new_with_schema("a", &schema()).unwrap()),
+        Operator::Eq,
+        Arc::new(
+            ScalarFunctionExpr::try_new(
+                Arc::new(ScalarUDF::from(RandomFunc::new())),
+                vec![],
+                &schema(),
+            )
+            .unwrap(),
+        ),
+    )) as Arc<dyn PhysicalExpr>;
+    let plan = Arc::new(FilterExec::try_new(predicate, scan).unwrap());
+    // expect the filter to not be pushed down
+    insta::assert_snapshot!(
+        OptimizationTest::new(plan, FilterPushdown::new(), true),
+        @r"
+    OptimizationTest:
+      input:
+        - FilterExec: a@0 = random()
+        -   DataSourceExec: file_groups={1 group: [[test.parquet]]}, projection=[a, b, c], file_type=test, pushdown_supported=true
+      output:
+        Ok:
+          - FilterExec: a@0 = random()
+          -   DataSourceExec: file_groups={1 group: [[test.parquet]]}, projection=[a, b, c], file_type=test, pushdown_supported=true
+    ",
+    );
+}
+
 /// Show that we can use config options to determine how to do pushdown.
 #[test]
 fn test_pushdown_into_scan_with_config_options() {

datafusion/core/tests/physical_optimizer/filter_pushdown/util.rs

@@ -26,7 +26,6 @@ use datafusion_datasource::{
     file_stream::FileOpener, schema_adapter::DefaultSchemaAdapterFactory,
     schema_adapter::SchemaAdapterFactory, source::DataSourceExec, PartitionedFile,
 };
-use datafusion_physical_expr::conjunction;
 use datafusion_physical_expr_common::physical_expr::fmt_sql;
 use datafusion_physical_optimizer::PhysicalOptimizerRule;
 use datafusion_physical_plan::filter_pushdown::{FilterPushdownPhase, PushedDown};
@@ -224,7 +223,9 @@ impl FileSource for TestSource {
                 filters.push(Arc::clone(internal));
             }
             let new_node = Arc::new(TestSource {
-                predicate: Some(conjunction(filters.clone())),
+                predicate: datafusion_physical_expr::utils::conjunction_opt(
+                    filters.clone(),
+                ),
                 ..self.clone()
             });
             Ok(FilterPushdownPropagation::with_parent_pushdown_result(