Does Doctrine DBAL support transaction‑wrapped ALTER TABLE for atomic rollback in MySQL?

Answer: No

Doctrine DBAL does not provide transaction-wrapped, rollback-capable ALTER TABLE for MySQL or MariaDB. Schema Manager methods such as addColumn and dropColumn generate DDL and execute it immediately through the Connection. No DBAL version supports wrapping those DDL statements in a user transaction that can be rolled back, and the Schema Manager cannot be configured to defer DDL execution until COMMIT.

Confirmed facts

• Schema Manager executes DDL immediately. addColumn, dropColumn and similar operations run ALTER TABLE at call time, not at commit time.
• TransactionGuard only guards transaction boundaries. It can trigger a rollback for data-manipulation errors, but it cannot undo DDL that has already been executed by the server.
• There is no DBAL configuration or version that defers Schema Manager DDL until commit, nor a mode that makes ALTER TABLE rollbackable via Doctrine.

Likely explanation

MySQL and MariaDB treat DDL outside normal transactional rollback by default. MySQL 5.x and MariaDB generally implicit-commit on DDL, so a Doctrine beginTransaction around ALTER TABLE will not reliably roll back the schema change.

MySQL 8.0+ introduced server-level atomic DDL for some ALTER TABLE forms. That makes an individual ALTER TABLE succeed or fail as a unit on the server, not a Doctrine transaction rollback across multiple statements. Coverage is statement- and version-dependent and it is not exposed as DBAL transactional DDL support.

Practical steps for this case

1. Assume no rollback. Treat every Schema Manager ALTER TABLE as permanent once executed.
2. Verify your server behavior on a disposable copy: create a table, begin a DBAL transaction, run SchemaManager addColumn or executeStatement('ALTER TABLE...'), then ROLLBACK and query information_schema.columns. Persistence of the column confirms no rollback.
3. Use tested migrations, backups or replicas for safety instead of relying on Doctrine transactions for schema changes.

Version assumptions: behavior described applies to Doctrine DBAL with MySQL and MariaDB drivers. Exact server version changes which ALTER forms are atomic on the server, but it does not enable Doctrine-level transactional ALTER TABLE rollback.