fix(cubesql): Disable projection_push_down DF optimizer

It can drop projection for mismatched alias in UNION ALL

Author: mcheshkov

rust/cubesql/cubesql/src/compile/query_engine.rs

@@ -394,15 +394,20 @@ impl QueryEngine for SqlQueryEngine {
             state.get_load_request_meta("sql"),
             self.config_ref().clone(),
         ));
-        let mut ctx = DFSessionContext::with_state(
-            default_session_builder(
-                DFSessionConfig::new()
-                    .create_default_catalog_and_schema(false)
-                    .with_information_schema(false)
-                    .with_default_catalog_and_schema("db", "public"),
-            )
-            .with_query_planner(query_planner),
-        );
+        let mut df_state = default_session_builder(
+            DFSessionConfig::new()
+                .create_default_catalog_and_schema(false)
+                .with_information_schema(false)
+                .with_default_catalog_and_schema("db", "public"),
+        )
+        .with_query_planner(query_planner);
+        df_state
+            .optimizer
+            .rules
+            // projection_push_down is broken even for non-OLAP queries
+            // TODO enable it back
+            .retain(|r| r.name() != "projection_push_down");
+        let mut ctx = DFSessionContext::with_state(df_state);
 
         if state.protocol == DatabaseProtocol::MySQL {
             let system_variable_provider =

rust/cubesql/cubesql/src/compile/snapshots/cubesql__compile__tests__explain-2.snap

@@ -12,7 +12,6 @@ expression: "execute_query(\"EXPLAIN VERBOSE SELECT 1+1;\".to_string(),\n
 | logical_plan after common_sub_expression_eliminate    | SAME TEXT AS ABOVE                              |
 | logical_plan after eliminate_limit                    | SAME TEXT AS ABOVE                              |
 | logical_plan after projection_drop_out                | SAME TEXT AS ABOVE                              |
-| logical_plan after projection_push_down               | SAME TEXT AS ABOVE                              |
 | logical_plan after filter_push_down                   | SAME TEXT AS ABOVE                              |
 | logical_plan after limit_push_down                    | SAME TEXT AS ABOVE                              |
 | logical_plan after SingleDistinctAggregationToGroupBy | SAME TEXT AS ABOVE                              |

rust/cubesql/cubesql/src/compile/test/snapshots/cubesql__compile__test__test_df_execution__union_all_alias_mismatch.snap

@@ -0,0 +1,9 @@
+---
+source: cubesql/src/compile/test/test_df_execution.rs
+expression: "execute_query(query.to_string(), DatabaseProtocol::PostgreSQL,).await.unwrap()"
+---
++-----+-----+
+| foo | bar |
++-----+-----+
+| foo | bar |
++-----+-----+

rust/cubesql/cubesql/src/compile/test/test_df_execution.rs

@@ -61,3 +61,33 @@ async fn test_triple_join_with_coercion() {
     .await
     .unwrap());
 }
+
+#[tokio::test]
+async fn union_all_alias_mismatch() {
+    init_testing_logger();
+
+    // language=PostgreSQL
+    let query = r#"
+SELECT
+    foo,
+    bar
+FROM (
+    SELECT
+        'foo' as foo,
+        'bar' as bar
+    UNION ALL
+    SELECT
+        'foo' as foo,
+        'bar' as qux
+) t
+GROUP BY
+    foo, bar
+;
+        "#;
+
+    insta::assert_snapshot!(
+        execute_query(query.to_string(), DatabaseProtocol::PostgreSQL,)
+            .await
+            .unwrap()
+    );
+}