Merge branch 'partial_schema_eq_deletes' into df50

# Conflicts:
#	crates/iceberg/src/arrow/caching_delete_file_loader.rs

Author: mbutrovich

crates/iceberg/src/arrow/caching_delete_file_loader.rs

@@ -224,14 +224,12 @@ impl CachingDeleteFileLoader {
                 let (sender, receiver) = channel();
                 del_filter.insert_equality_delete(&task.file_path, receiver);
 
+                // Equality deletes intentionally have partial schemas. Schema evolution would add
+                // NULL values for missing REQUIRED columns, causing Arrow validation to fail.
                 Ok(DeleteFileContext::FreshEqDel {
-                    batch_stream: BasicDeleteFileLoader::evolve_schema(
-                        basic_delete_file_loader
-                            .parquet_to_batch_stream(&task.file_path)
-                            .await?,
-                        schema,
-                    )
-                    .await?,
+                    batch_stream: basic_delete_file_loader
+                        .parquet_to_batch_stream(&task.file_path)
+                        .await?,
                     sender,
                     equality_ids: HashSet::from_iter(task.equality_ids.clone().unwrap()),
                 })
@@ -687,6 +685,91 @@ mod tests {
         assert!(result.is_none()); // no pos dels for file 3
     }
 
+    /// Verifies that evolve_schema on partial-schema equality deletes fails with Arrow
+    /// validation errors when missing REQUIRED columns are filled with NULLs.
+    ///
+    /// Reproduces the issue that caused 14 TestSparkReaderDeletes failures in Iceberg Java.
+    #[tokio::test]
+    async fn test_partial_schema_equality_deletes_evolve_fails() {
+        let tmp_dir = TempDir::new().unwrap();
+        let table_location = tmp_dir.path().as_os_str().to_str().unwrap();
+
+        // Create table schema with REQUIRED fields
+        let table_schema = Arc::new(
+            Schema::builder()
+                .with_schema_id(1)
+                .with_fields(vec![
+                    crate::spec::NestedField::required(
+                        1,
+                        "id",
+                        crate::spec::Type::Primitive(crate::spec::PrimitiveType::Int),
+                    )
+                    .into(),
+                    crate::spec::NestedField::required(
+                        2,
+                        "data",
+                        crate::spec::Type::Primitive(crate::spec::PrimitiveType::String),
+                    )
+                    .into(),
+                ])
+                .build()
+                .unwrap(),
+        );
+
+        // Write equality delete file with PARTIAL schema (only 'data' column)
+        let delete_file_path = {
+            let data_vals = vec!["a", "d", "g"];
+            let data_col = Arc::new(StringArray::from(data_vals)) as ArrayRef;
+
+            let delete_schema = Arc::new(arrow_schema::Schema::new(vec![simple_field(
+                "data",
+                DataType::Utf8,
+                false,
+                "2", // field ID
+            )]));
+
+            let delete_batch = RecordBatch::try_new(delete_schema.clone(), vec![data_col]).unwrap();
+
+            let path = format!("{}/partial-eq-deletes.parquet", &table_location);
+            let file = File::create(&path).unwrap();
+            let props = WriterProperties::builder()
+                .set_compression(Compression::SNAPPY)
+                .build();
+            let mut writer =
+                ArrowWriter::try_new(file, delete_batch.schema(), Some(props)).unwrap();
+            writer.write(&delete_batch).expect("Writing batch");
+            writer.close().unwrap();
+            path
+        };
+
+        let file_io = FileIO::from_path(table_location).unwrap().build().unwrap();
+        let basic_delete_file_loader = BasicDeleteFileLoader::new(file_io.clone());
+
+        let batch_stream = basic_delete_file_loader
+            .parquet_to_batch_stream(&delete_file_path)
+            .await
+            .unwrap();
+
+        let mut evolved_stream = BasicDeleteFileLoader::evolve_schema(batch_stream, table_schema)
+            .await
+            .unwrap();
+
+        let result = evolved_stream.next().await.unwrap();
+
+        assert!(
+            result.is_err(),
+            "Expected error from evolve_schema adding NULL to non-nullable column"
+        );
+
+        let err = result.unwrap_err();
+        let err_msg = err.to_string();
+        assert!(
+            err_msg.contains("non-nullable") || err_msg.contains("null values"),
+            "Expected null value error, got: {}",
+            err_msg
+        );
+    }
+
     /// Test loading a FileScanTask with BOTH positional and equality deletes.
     /// Verifies the fix for the inverted condition that caused "Missing predicate for equality delete file" errors.
     #[tokio::test]