dont change __user / __cubejoinfield names in aliasing

Author: Nikita-str

packages/cubejs-schema-compiler/src/adapter/BaseQuery.js

@@ -2646,6 +2646,9 @@ export class BaseQuery {
     }
     // TODO: https://github.com/cube-js/cube.js/issues/4019
     // use single underscore for pre-aggregations to avoid fail of pre-aggregation name replace
+    if (name === '__user' || name === '__cubejoinfield') {
+      return name;
+    }
     return inflection.underscore(name).replace(/\./g, isPreAggregationName ? '_' : '__');
   }
 

rust/cubesql/cubesql/src/compile/engine/df/wrapper.rs

@@ -925,10 +925,7 @@ impl CubeScanWrapperNode {
 
             let alias = if can_rename_columns {
                 let alias = expr_name(&expr, &schema)?;
-                let mut truncated_alias = non_id_regex
-                    .replace_all(&alias, "_")
-                    .trim_start_matches("_")
-                    .to_lowercase();
+                let mut truncated_alias = non_id_regex.replace_all(&alias, "_").to_lowercase();
                 truncated_alias.truncate(16);
                 let mut alias = truncated_alias.clone();
                 for i in 1..10000 {

rust/cubesql/cubesql/src/compile/mod.rs

@@ -20497,8 +20497,8 @@ ORDER BY "source"."str0" ASC
                 .wrapped_sql
                 .unwrap()
                 .sql
-                .contains("\\\"cube_name\\\":\\\"KibanaSampleDataEcommerce\\\",\\\"alias\\\":\\\"user\\\""),
-            r#"SQL contains `\"cube_name\":\"KibanaSampleDataEcommerce\",\"alias\":\"user\"` {}"#,
+                .contains("\\\"cube_name\\\":\\\"KibanaSampleDataEcommerce\\\",\\\"alias\\\":\\\"__user\\\""),
+            r#"SQL contains `\"cube_name\":\"KibanaSampleDataEcommerce\",\"alias\":\"__user\"` {}"#,
             logical_plan
                 .find_cube_scan_wrapper()
                 .wrapped_sql