fix: Preserves field metadata when creating logical plan for VALUES expression

datafusion/core/tests/user_defined/user_defined_scalar_functions.rs

@@ -1833,6 +1833,87 @@ async fn test_config_options_work_for_scalar_func() -> Result<()> {
     Ok(())
 }
 
+/// https://github.com/apache/datafusion/issues/17425
+#[tokio::test]
+async fn test_extension_metadata_preserve_in_sql_values() -> Result<()> {
+    #[derive(Debug, Hash, PartialEq, Eq)]
+    struct MakeExtension {
+        signature: Signature,
+    }
+
+    impl Default for MakeExtension {
+        fn default() -> Self {
+            Self {
+                signature: Signature::user_defined(Volatility::Immutable),
+            }
+        }
+    }
+
+    impl ScalarUDFImpl for MakeExtension {
+        fn as_any(&self) -> &dyn Any {
+            self
+        }
+
+        fn name(&self) -> &str {
+            "make_extension"
+        }
+
+        fn signature(&self) -> &Signature {
+            &self.signature
+        }
+
+        fn coerce_types(&self, arg_types: &[DataType]) -> Result<Vec<DataType>> {
+            Ok(arg_types.to_vec())
+        }
+
+        fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
+            unreachable!("This shouldn't have been called")
+        }
+
+        fn return_field_from_args(&self, args: ReturnFieldArgs) -> Result<FieldRef> {
+            Ok(args.arg_fields[0]
+                .as_ref()
+                .clone()
+                .with_metadata(HashMap::from([(
+                    "ARROW:extension:metadata".to_string(),
+                    "foofy.foofy".to_string(),
+                )]))
+                .into())
+        }
+
+        fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
+            Ok(args.args[0].clone())
+        }
+    }
+
+    let ctx = SessionContext::new();
+    ctx.register_udf(MakeExtension::default().into());
+
+    let batches = ctx
+        .sql(
+            "
+SELECT extension FROM (VALUES
+    ('one', make_extension('foofy one')),
+    ('two', make_extension('foofy two')),
+    ('three', make_extension('foofy three')))
+AS t(string, extension)
+        ",
+        )
+        .await?
+        .collect()
+        .await?;
+
+    assert_eq!(
+        batches[0]
+            .schema()
+            .field(0)
+            .metadata()
+            .get("ARROW:extension:metadata"),
+        Some(&"foofy.foofy".into())
+    );
+    Ok(())
+}
+
 /// https://github.com/apache/datafusion/issues/17422
 #[tokio::test]
 async fn test_extension_metadata_preserve_in_subquery() -> Result<()> {

datafusion/expr/src/logical_plan/builder.rs

@@ -25,7 +25,7 @@ use std::iter::once;
 use std::sync::Arc;
 
 use crate::dml::CopyTo;
-use crate::expr::{Alias, PlannedReplaceSelectItem, Sort as SortExpr};
+use crate::expr::{Alias, FieldMetadata, PlannedReplaceSelectItem, Sort as SortExpr};
 use crate::expr_rewriter::{
     coerce_plan_expr_for_schema, normalize_col,
     normalize_col_with_schemas_and_ambiguity_check, normalize_cols, normalize_sorts,
@@ -306,8 +306,17 @@ impl LogicalPlanBuilder {
 
         for j in 0..n_cols {
             let mut common_type: Option<DataType> = None;
+            let mut common_metadata: Option<FieldMetadata> = None;
             for (i, row) in values.iter().enumerate() {
                 let value = &row[j];
+                let metadata = value.metadata(&schema)?;
+                if let Some(ref cm) = common_metadata {
+                    if &metadata != cm {
+                        return plan_err!("Inconsistent metadata across values list at row {i} column {j}. Was {:?} but found {:?}", cm, metadata);
+                    }
+                } else {
+                    common_metadata = Some(metadata.clone());
+                }
                 let data_type = value.get_type(&schema)?;
                 if data_type == DataType::Null {
                     continue;
@@ -326,7 +335,11 @@ impl LogicalPlanBuilder {
             }
             // assuming common_type was not set, and no error, therefore the type should be NULL
             // since the code loop skips NULL
-            fields.push(common_type.unwrap_or(DataType::Null), true);
+            fields.push_with_metadata(
+                common_type.unwrap_or(DataType::Null),
+                true,
+                common_metadata,
+            );
         }
 
         Self::infer_inner(values, fields, &schema)
@@ -1507,10 +1520,23 @@ impl ValuesFields {
     }
 
     pub fn push(&mut self, data_type: DataType, nullable: bool) {
+        self.push_with_metadata(data_type, nullable, None);
+    }
+
+    pub fn push_with_metadata(
+        &mut self,
+        data_type: DataType,
+        nullable: bool,
+        metadata: Option<FieldMetadata>,
+    ) {
         // Naming follows the convention described here:
         // https://www.postgresql.org/docs/current/queries-values.html
         let name = format!("column{}", self.inner.len() + 1);
-        self.inner.push(Field::new(name, data_type, nullable));
+        let mut field = Field::new(name, data_type, nullable);
+        if let Some(metadata) = metadata {
+            field.set_metadata(metadata.to_hashmap());
+        }
+        self.inner.push(field);
     }
 
     pub fn into_fields(self) -> Fields {
@@ -2153,7 +2179,10 @@ pub fn unnest_with_options(
 
 #[cfg(test)]
 mod tests {
+    use std::vec;
+
     use super::*;
+    use crate::lit_with_metadata;
     use crate::logical_plan::StringifiedPlan;
     use crate::{col, expr, expr_fn::exists, in_subquery, lit, scalar_subquery};
 
@@ -2773,6 +2802,35 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn test_values_metadata() -> Result<()> {
+        let metadata: HashMap<String, String> =
+            [("ARROW:extension:metadata".to_string(), "test".to_string())]
+                .into_iter()
+                .collect();
+        let metadata = FieldMetadata::from(metadata);
+        let values = LogicalPlanBuilder::values(vec![
+            vec![lit_with_metadata(1, Some(metadata.clone()))],
+            vec![lit_with_metadata(2, Some(metadata.clone()))],
+        ])?
+        .build()?;
+        assert_eq!(*values.schema().field(0).metadata(), metadata.to_hashmap());
+
+        // Do not allow VALUES with different metadata mixed together
+        let metadata2: HashMap<String, String> =
+            [("ARROW:extension:metadata".to_string(), "test2".to_string())]
+                .into_iter()
+                .collect();
+        let metadata2 = FieldMetadata::from(metadata2);
+        assert!(LogicalPlanBuilder::values(vec![
+            vec![lit_with_metadata(1, Some(metadata.clone()))],
+            vec![lit_with_metadata(2, Some(metadata2.clone()))],
+        ])
+        .is_err());
+
+        Ok(())
+    }
+
     #[test]
     fn test_unique_field_aliases() {
         let t1_field_1 = Field::new("a", DataType::Int32, false);