fix: Wrap is_null expressions in parens, to avoid operator precedence issues

Expression like `(foo IS NOT NULL = bar IS NOT NULL)`` would try to compare `foo IS NOT NULL` with `bar`, not with `bar IS NOT NULL`

Author: mcheshkov

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

@@ -3327,7 +3327,7 @@ export class BaseQuery {
         column_aliased: '{{expr}} {{quoted_alias}}',
         query_aliased: '{{ query }} AS {{ quoted_alias }}',
         case: 'CASE{% if expr %} {{ expr }}{% endif %}{% for when, then in when_then %} WHEN {{ when }} THEN {{ then }}{% endfor %}{% if else_expr %} ELSE {{ else_expr }}{% endif %} END',
-        is_null: '{{ expr }} IS {% if negate %}NOT {% endif %}NULL',
+        is_null: '({{ expr }} IS {% if negate %}NOT {% endif %}NULL)',
         binary: '({{ left }} {{ op }} {{ right }})',
         sort: '{{ expr }} {% if asc %}ASC{% else %}DESC{% endif %} NULLS {% if nulls_first %}FIRST{% else %}LAST{% endif %}',
         order_by: '{% if index %} {{ index }} {% else %} {{ expr }} {% endif %} {% if asc %}ASC{% else %}DESC{% endif %}{% if nulls_first %} NULLS FIRST{% endif %}',

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

@@ -12188,7 +12188,7 @@ ORDER BY "source"."str0" ASC
         }
         init_testing_logger();
 
-        let logical_plan = convert_select_to_query_plan(
+        let query_plan = convert_select_to_query_plan(
             r#"
             WITH "qt_0" AS (
                 SELECT "ta_1"."customer_gender" "ca_1"
@@ -12205,13 +12205,20 @@ ORDER BY "source"."str0" ASC
             .to_string(),
             DatabaseProtocol::PostgreSQL,
         )
-        .await
-        .as_logical_plan();
+        .await;
+
+        let physical_plan = query_plan.as_physical_plan().await.unwrap();
+        println!(
+            "Physical plan: {}",
+            displayable(physical_plan.as_ref()).indent()
+        );
+
+        let logical_plan = query_plan.as_logical_plan();
 
         let sql = logical_plan.find_cube_scan_wrapped_sql().wrapped_sql.sql;
 
-        // check wrapping for `NOT(.. IS NULL OR LOWER(..) IN)`
-        let re = Regex::new(r"NOT \(.+ IS NULL OR .*LOWER\(.+ IN ").unwrap();
+        // check wrapping for `NOT((.. IS NULL) OR LOWER(..) IN)`
+        let re = Regex::new(r"NOT \(\(.+ IS NULL\) OR .*LOWER\(.+ IN ").unwrap();
         assert!(re.is_match(&sql));
     }
 

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

@@ -578,7 +578,7 @@ OFFSET {{ offset }}{% endif %}"#.to_string(),
                         "{{expr}} {{quoted_alias}}".to_string(),
                     ),
                     ("expressions/binary".to_string(), "({{ left }} {{ op }} {{ right }})".to_string()),
-                    ("expressions/is_null".to_string(), "{{ expr }} IS {% if negate %}NOT {% endif %}NULL".to_string()),
+                    ("expressions/is_null".to_string(), "({{ expr }} IS {% if negate %}NOT {% endif %}NULL)".to_string()),
                     ("expressions/case".to_string(), "CASE{% if expr %} {{ expr }}{% endif %}{% for when, then in when_then %} WHEN {{ when }} THEN {{ then }}{% endfor %}{% if else_expr %} ELSE {{ else_expr }}{% endif %} END".to_string()),
                     ("expressions/sort".to_string(), "{{ expr }} {% if asc %}ASC{% else %}DESC{% endif %}{% if nulls_first %} NULLS FIRST {% endif %}".to_string()),
                     ("expressions/cast".to_string(), "CAST({{ expr }} AS {{ data_type }})".to_string()),

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

@@ -1174,7 +1174,7 @@ WHERE
     let last_mod_month_re =
         Regex::new(r#""logs_alias"."[a-zA-Z0-9_]{1,16}" "last_mod_month""#).unwrap();
     assert!(last_mod_month_re.is_match(&sql));
-    let sum_price_re = Regex::new(r#"CASE WHEN "logs_alias"."[a-zA-Z0-9_]{1,16}" IS NOT NULL THEN "logs_alias"."[a-zA-Z0-9_]{1,16}" ELSE 0 END "sum_price""#)
+    let sum_price_re = Regex::new(r#"CASE WHEN \("logs_alias"."[a-zA-Z0-9_]{1,16}" IS NOT NULL\) THEN "logs_alias"."[a-zA-Z0-9_]{1,16}" ELSE 0 END "sum_price""#)
         .unwrap();
     assert!(sum_price_re.is_match(&sql));
     let cube_user_re = Regex::new(r#""logs_alias"."[a-zA-Z0-9_]{1,16}" "cube_user""#).unwrap();