Use transaction to test importing first, then the transaction will be rollbacked. The trial result will be shown to user for confirming or denying import. Default value is true.
**Important**
1. Database/Table must support transaction for this to work, e.g. if you use MySQL, you should use table with **InnoDB** engine.
1. If the table uses auto-increment field, note that there will be sequence gap after rollback. For MySQL, read [AUTO_INCREMENT Handling in InnoDB](https://dev.mysql.com/doc/refman/8.0/en/innodb-auto-increment-handling.html) -> _"Lost" auto-increment values and sequence gaps_.