databricks · vikrantpuppala · Apr 23, 2026 · Apr 23, 2026
diff --git a/tests/e2e/test_transactions.py b/tests/e2e/test_transactions.py
@@ -624,17 +624,21 @@ def test_cursor_tables_non_transactional_after_concurrent_create(
 class TestMstBlockedSql:
    """SQL introspection statements inside active transactions.

-    The server restricts MST to a specific allowlist of commands. The error
-    message from TRANSACTION_NOT_SUPPORTED.COMMAND is explicit:
+    The server restricts MST to an allowlist enforced by MSTCheckRule. The
+    TRANSACTION_NOT_SUPPORTED.COMMAND error originally advertised only:
    "Only SELECT / INSERT / MERGE / UPDATE / DELETE / DESCRIBE TABLE are supported."

+    The server has since broadened the allowlist to include SHOW COLUMNS
+    (ShowDeltaTableColumnsCommand), observed on current DBSQL warehouses.
+
    Blocked (throw + abort txn):
-    - SHOW COLUMNS, SHOW TABLES, SHOW SCHEMAS, SHOW CATALOGS, SHOW FUNCTIONS
+    - SHOW TABLES, SHOW SCHEMAS, SHOW CATALOGS, SHOW FUNCTIONS
    - DESCRIBE QUERY, DESCRIBE TABLE EXTENDED
    - SELECT FROM information_schema

    Allowed:
-    - DESCRIBE TABLE (basic form — explicitly listed in server's allowlist)
+    - DESCRIBE TABLE (basic form)
+    - SHOW COLUMNS
    """

    def _assert_blocked_and_txn_aborted(self, mst_conn_params, fq_table, blocked_sql):
@@ -704,10 +708,10 @@ def test_information_schema_blocked(self, mst_conn_params, mst_table, mst_catalo
            f"SELECT * FROM {mst_catalog}.information_schema.columns LIMIT 1",
        )

-    def test_show_columns_blocked(self, mst_conn_params, mst_table):
-        """SHOW COLUMNS is blocked in MST (ShowDeltaTableColumnsCommand)."""
+    def test_show_columns_not_blocked(self, mst_conn_params, mst_table):
+        """SHOW COLUMNS succeeds in MST — allowed by the server's MSTCheckRule allowlist."""
        fq_table, _ = mst_table
-        self._assert_blocked_and_txn_aborted(
+        self._assert_not_blocked(
            mst_conn_params, fq_table, f"SHOW COLUMNS IN {fq_table}"
        )