SELECT @@system_variable syntaxΒΆ

SELECT @@system_variable [LIMIT [offset,] row_count]

This is currently a placeholder query that does nothing and reports success. That is in order to keep compatibility with frameworks and connectors that automatically execute this statement.

However @@session.last_insert_id and LAST_INSERT_ID() report ID of documents these were inserted or replaced well at last statement.

mysql> select @@session.last_insert_id;
+--------------------------+
| @@session.last_insert_id |
+--------------------------+
| 11,32                    |
+--------------------------+
1 rows in set

mysql> select LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
| 25,26,29         |
+------------------+
1 rows in set