fix(query-engine): address code-review cleanup findings on PR #567 Stage 3 cutover

- move plan_execution_arithmetic_tests.rs out of tests/datafusion/ since it
  now exercises the native binary-expr path, not DataFusion
- fix warn! in evaluate_binary_arm that mislabeled any execute_query_pipeline
  error as "produced no results"
- mark orphaned execute_logical_plan #[allow(dead_code)] and update its doc
  comment, matching its sibling execute_plan
- avoid an unnecessary Vec<String> clone in combine_vector_vector
- mark design-252 doc as superseded by the native cutover in #567

Author: milindsrivastava1997

asap-query-engine/src/engines/simple_engine/mod.rs

@@ -823,8 +823,11 @@ impl SimpleEngine {
 
     /// Executes a pre-built DataFusion logical plan and returns results.
     ///
-    /// This is the shared execution kernel used by both `execute_plan` (for single-metric
-    /// queries) and the binary arithmetic dispatch path.
+    /// This was the shared execution kernel for `execute_plan` and the DataFusion-based
+    /// binary arithmetic dispatch path; the latter was cut over to a native implementation
+    /// in #567, leaving this unused in production. Kept alongside `execute_plan` as part
+    /// of the still-exercised DataFusion path (see its dedicated tests).
+    #[allow(dead_code)]
     pub async fn execute_logical_plan(
         &self,
         logical_plan: datafusion::logical_expr::LogicalPlan,

asap-query-engine/src/engines/simple_engine/promql.rs

@@ -66,9 +66,9 @@ fn combine_vector_vector(
         lhs_results
             .into_iter()
             .filter_map(|lhs_elem| {
-                rhs_map.get(&lhs_elem.labels).map(|&rhs_val| {
+                rhs_map.get(&lhs_elem.labels).map(move |&rhs_val| {
                     let value = SimpleEngine::apply_range_binary_op(op, lhs_elem.value, rhs_val);
-                    InstantVectorElement::new(lhs_elem.labels.clone(), value)
+                    InstantVectorElement::new(lhs_elem.labels, value)
                 })
             })
             .collect(),
@@ -469,7 +469,7 @@ impl SimpleEngine {
                     .execute_query_pipeline(&ctx, true, true)
                     .map_err(|e| {
                         warn!(
-                            "Binary-expr arm for metric '{}' produced no results ({}) — \
+                            "Binary-expr arm for metric '{}' failed ({}) — \
                              falls back to Prometheus for the whole expression rather than \
                              returning an empty result for just this arm",
                             ctx.metric, e

asap-query-engine/src/tests/datafusion/mod.rs

@@ -7,7 +7,6 @@ pub mod accumulator_serde_tests;
 pub mod dispatch_arithmetic_tests;
 pub mod plan_builder_binary_tests;
 pub mod plan_builder_regression_tests;
-pub mod plan_execution_arithmetic_tests;
 pub mod plan_execution_dual_input_tests;
 pub mod plan_execution_temporal_tests;
 pub mod plan_execution_tests;

asap-query-engine/src/tests/mod.rs

@@ -3,6 +3,7 @@ pub mod clickhouse_forwarding_tests;
 pub mod datafusion;
 pub mod elastic_dsl_query_tests;
 pub mod elastic_forwarding_tests;
+pub mod native_binary_arithmetic_plan_tests;
 pub mod native_binary_instant_tests;
 pub mod native_pipeline_merge_tests;
 pub mod prometheus_forwarding_tests;

…usion/plan_execution_arithmetic_tests.rs …s/native_binary_arithmetic_plan_tests.rsasap-query-engine/src/tests/datafusion/plan_execution_arithmetic_tests.rs renamed to asap-query-engine/src/tests/native_binary_arithmetic_plan_tests.rs asap-query-engine/src/tests/datafusion/plan_execution_arithmetic_tests.rs renamed to asap-query-engine/src/tests/native_binary_arithmetic_plan_tests.rs

@@ -1,5 +1,14 @@
 # Design: PromQL Arithmetic Operator Acceleration (Issue #252)
 
+> **Superseded (#567):** the DataFusion execution path described below
+> (`execute_plan`/`execute_logical_plan`, the `Join + Projection` plan) was
+> replaced by a purely native execution path in `handle_binary_expr_promql` /
+> `evaluate_binary_arm` / `combine_vector_vector` / `combine_scalar`
+> (`asap-query-engine/src/engines/simple_engine/promql.rs`). The DataFusion
+> code is kept only for its own dedicated tests and is no longer reachable
+> from production. This doc is retained as the historical record of the
+> original design decision.
+
 ## Problem
 
 ASAPQuery accelerates PromQL queries by pre-computing sketches over streaming data and serving answers from those sketches at query time, bypassing the underlying TSDB for supported query patterns.