Final answer:
An irrecoverable error in a database system can occur when a transaction reads a data item after it is written by an uncommitted transaction, resulting in inconsistencies and data corruption.
Step-by-step explanation:
In a database system, an irrecoverable error can occur when a transaction reads a data item after it is written by an uncommitted transaction. This is known as a dirty read. When a transaction reads uncommitted data, it may encounter inconsistencies or incorrect information, which can lead to errors and data corruption.
For example, let's say Transaction A reads a data item and Transaction B then writes to that same data item, but has not yet committed the changes. If Transaction C reads the data item after Transaction B's write, it will see the uncommitted value, which may be different from the actual committed value. This can result in incorrect calculations, inaccurate reports, or other errors.
To avoid irrecoverable errors, database systems use mechanisms such as locks, isolation levels, and transaction control to ensure data integrity and prevent dirty reads.