Why Is Transaction Integrity Important?

The advantage of describing a group of related data source commands as one logical transaction is that the transaction is valid and written to the data source only if all of its component commands are successful. When you attempt to commit a transaction, you are ensured that if part of the transaction fails, none of the transaction will be written to the data source. This is called transaction integrity.

When is transaction integrity important? Whenever a group of commands are related and are only meaningful within the context of the group. In other words, whenever the failure of any one command in the transaction at commit-time would invalidate the entire transaction.

Transaction integrity is an uncompromising proposition: either all of the transaction is written to the data source when you commit it, or all of it is rolled back.

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Example: Why Transaction Integrity Is Essential to a Bank

Consider a banking application that transfers funds from a savings account to a checking account. If the application successfully subtracts the funds from the savings account, but is interrupted by a system problem before it can add the funds to the checking account, the money would disappear, creating unbalanced bank accounts.

The two update commands (subtracting and adding funds) must be described as parts of a single logical transaction, so that the subtraction and addition updates are not written to the data source independently of each other.