fix: Render LIMIT 0 and OFFSET 0 properly in SQL templates (#8781)

`if limit` condition in Jinja will fail for both None and Some(0)
This is more or less fine for offset, but completely wrong for limit. For consistency both are changed.

Also add unit test in SQL API and smoke E2E test

Author: mcheshkov

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

@@ -3217,8 +3217,8 @@ export class BaseQuery {
           '{% if filter %}\nWHERE {{ filter }}{% endif %}' +
           '{% if group_by %}\nGROUP BY {{ group_by }}{% endif %}' +
           '{% if order_by %}\nORDER BY {{ order_by | map(attribute=\'expr\') | join(\', \') }}{% endif %}' +
-          '{% if limit %}\nLIMIT {{ limit }}{% endif %}' +
-          '{% if offset %}\nOFFSET {{ offset }}{% endif %}',
+          '{% if limit is not none %}\nLIMIT {{ limit }}{% endif %}' +
+          '{% if offset is not none %}\nOFFSET {{ offset }}{% endif %}',
         group_by_exprs: '{{ group_by | map(attribute=\'index\') | join(\', \') }}',
       },
       expressions: {

packages/cubejs-schema-compiler/src/adapter/PrestodbQuery.ts

@@ -116,8 +116,8 @@ export class PrestodbQuery extends BaseQuery {
       'FROM (\n  {{ from }}\n) AS {{ from_alias }} \n' +
       '{% if group_by %} GROUP BY {{ group_by }}{% endif %}' +
       '{% if order_by %} ORDER BY {{ order_by | map(attribute=\'expr\') | join(\', \') }}{% endif %}' +
-      '{% if offset %}\nOFFSET {{ offset }}{% endif %}' +
-      '{% if limit %}\nLIMIT {{ limit }}{% endif %}';
+      '{% if offset is not none %}\nOFFSET {{ offset }}{% endif %}' +
+      '{% if limit is not none %}\nLIMIT {{ limit }}{% endif %}';
     templates.expressions.extract = 'EXTRACT({{ date_part }} FROM {{ expr }})';
     templates.expressions.interval_single_date_part = 'INTERVAL \'{{ num }}\' {{ date_part }}';
     templates.expressions.timestamp_literal = 'from_iso8601_timestamp(\'{{ value }}\')';

packages/cubejs-testing/test/smoke-cubesql.test.ts

@@ -390,6 +390,13 @@ describe('SQL API', () => {
       expect(res.rows).toEqual([]);
     });
 
+    test('zero limited dimension aggregated queries through wrapper', async () => {
+      // Attempts to trigger query generation from SQL templates, not from Cube
+      const query = 'SELECT MIN(t.maxval) FROM (SELECT MAX(createdAt) as maxval FROM Orders LIMIT 10) t LIMIT 0';
+      const res = await connection.query(query);
+      expect(res.rows).toEqual([]);
+    });
+
     test('select dimension agg where false', async () => {
       const query =
           'SELECT MAX("createdAt") AS "max" FROM "BigOrders" WHERE 1 = 0';

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

@@ -15455,8 +15455,8 @@ ORDER BY "source"."str0" ASC
                     r#"SELECT {{ select_concat | map(attribute='aliased') | join(', ') }}
 FROM ({{ from }}) AS {{ from_alias }}
 {% if group_by %} GROUP BY {{ group_by | map(attribute='index') | join(', ') }}{% endif %}
-{% if order_by %} ORDER BY {{ order_by | map(attribute='expr') | join(', ') }}{% endif %}{% if offset %}
-OFFSET {{ offset }}{% endif %}{% if limit %}
+{% if order_by %} ORDER BY {{ order_by | map(attribute='expr') | join(', ') }}{% endif %}{% if offset is not none %}
+OFFSET {{ offset }}{% endif %}{% if limit is not none %}
 LIMIT {{ limit }}{% endif %}"#.to_string(),
                 ),
             ]

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

@@ -506,8 +506,8 @@ FROM (
 ) AS {{ from_alias }} {% endif %} {% if filter %}
 WHERE {{ filter }}{% endif %}{% if group_by %}
 GROUP BY {{ group_by }}{% endif %}{% if order_by %}
-ORDER BY {{ order_by | map(attribute='expr') | join(', ') }}{% endif %}{% if limit %}
-LIMIT {{ limit }}{% endif %}{% if offset %}
+ORDER BY {{ order_by | map(attribute='expr') | join(', ') }}{% endif %}{% if limit is not none %}
+LIMIT {{ limit }}{% endif %}{% if offset is not none %}
 OFFSET {{ offset }}{% endif %}"#.to_string(),
                     ),
                     (

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

@@ -964,3 +964,40 @@ async fn test_case_wrapper_escaping() {
         // Expect 6 backslashes as output is JSON and it's escaped one more time
         .contains("\\\\\\\\\\\\`"));
 }
+
+/// Test that WrappedSelect(... limit=Some(0) ...) will render it correctly
+#[tokio::test]
+async fn test_wrapper_limit_zero() {
+    if !Rewriter::sql_push_down_enabled() {
+        return;
+    }
+    init_testing_logger();
+
+    let query_plan = convert_select_to_query_plan(
+        // language=PostgreSQL
+        r#"
+            SELECT
+                MIN(t.a)
+            FROM (
+                SELECT
+                    MAX(order_date) AS a
+                FROM
+                    KibanaSampleDataEcommerce
+                LIMIT 10
+            ) t LIMIT 0
+            "#
+        .to_string(),
+        DatabaseProtocol::PostgreSQL,
+    )
+    .await;
+
+    let logical_plan = query_plan.as_logical_plan();
+    assert!(logical_plan
+        .find_cube_scan_wrapper()
+        .wrapped_sql
+        .unwrap()
+        .sql
+        .contains("LIMIT 0"));
+
+    let _physical_plan = query_plan.as_physical_plan().await.unwrap();
+}