How do Django atomic blocks, savepoints, and on_commit callbacks work together?

Defines Django transaction nesting, exception boundaries, and post-commit work without promising durability.

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The outermost transaction.atomic() block opens a transaction, and nested atomic blocks normally create savepoints. Leaving a block successfully commits its transaction or releases its savepoint; an exception rolls back to the matching boundary. I catch expected database exceptions outside the atomic block that should roll back, not inside a broken transaction. This keeps Django aware of whether later queries are valid.

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Defines Django transaction nesting, exception boundaries, and post-commit work without promising durability.

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Defines Django transaction nesting, exception boundaries, and post-commit work without promising durability.
The outermost transaction.atomic() block opens a transaction, and nested atomic blocks normally create savepoints. Leaving a block successfully commits its transaction or releases its savepoint; an exception rolls back to the matching boundary. I catch expected database exceptions outside the atomic block that should roll back, not inside a broken transaction. This keeps Django aware of whether later queries are valid.
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transaction.on_commit() registers work to run only after the outer transaction commits successfully. A callback registered inside a savepoint is discarded if that savepoint rolls back. It is useful for cache invalidation or starting noncritical follow-up work after data is visible, but the callback is not part of the database transaction and its failure cannot roll back the commit. Django tests also need deliberate handling because normally never commits.

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Catching integrity errors inside the same atomic block
Treating on_commit as durable messaging
Wrapping slow external calls in a transaction

How do Django atomic blocks, savepoints, and on_commit callbacks work together?

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