PostgreSQL, Second Edition

A (Very) Short Introduction to Transaction Processing

You might have noticed two new commands in this example. The BEGIN WORK and ROLLBACK commands are used for transaction processing. A transaction is a group of commands. Usually, a transaction includes one or more table modifications (INSERTs, DELETEs, and UPDATEs).

BEGIN WORK marks the beginning of a transaction. Inside of a transaction, any changes that you make to the database are temporary changes. There are two ways to mark the end of a transaction: COMMIT and ROLLBACK. If you COMMIT a transaction, you are telling PostgreSQL to write all the changes made within the transaction into the database—in other words, when you COMMIT a transaction, the changes become permanent. When you ROLLBACK ...