Rollback¶
A rollback is the process of reverting a system, database, or deployment to a previous known-good state after a failure or undesirable change.
In the context of databases, a rollback undoes all changes made since the beginning of a transaction, restoring the data to its state before the transaction started. PHP database extensions (PDO, MySQLi) support transactional rollback.
In the context of deployments, a rollback means re-deploying an earlier version of the application when a new release introduces critical bugs or regressions. Tools such as Deployer, Envoyer, Capistrano, and Kubernetes support deployment rollbacks.
In version control, a rollback can mean reverting a commit or resetting a branch to an earlier state using git revert or git reset.
Having a reliable rollback strategy is a key aspect of safe deployments and system resilience.
<?php
// Database transaction rollback with PDO
$pdo = new PDO('mysql:host=localhost;dbname=shop', 'user', 'pass');
try {
$pdo->beginTransaction();
$pdo->exec("UPDATE accounts SET balance = balance - 100 WHERE id = 1");
$pdo->exec("UPDATE accounts SET balance = balance + 100 WHERE id = 2");
$pdo->commit();
} catch (Throwable $e) {
$pdo->rollBack(); // Revert both changes
throw $e;
}
?>
See also PDO::rollBack() and Deployer rollback.
Related : Database, PHP Data Objects (PDO), Transaction, Deployment, git, Migration, Error Handling, Database Commit, Timing Attack, VCS Commit
