Transaction¶

Transaction handles BEGIN, COMMIT, and ROLLBACK. Implement its methods to support transactions.

With the defaults, statements run without a transaction and BEGIN returns an unsupported error. SAVEPOINT is not supported.

Use the shared Test Suite for commit and rollback behavior. Transaction isolation can differ between storages, so add integration tests for the guarantees your storage provides.

pub trait Transaction {
    fn begin(&mut self, autocommit: bool) -> Result<bool>;

    fn rollback(&mut self) -> Result<()>;

    fn commit(&mut self) -> Result<()>;
}

Automatic and explicit transactions¶

begin(true) is used for automatic transactions around the planning and execution of one SQL statement. Its return value controls how the transaction is finished:

• Return Ok(true) when the call starts a transaction that should be committed automatically on success or rolled back on failure.
• Return Ok(false) when the call should not be followed by an automatic commit or rollback, such as when reusing an existing transaction.

An explicit BEGIN calls begin(false). Keep that transaction open until COMMIT or ROLLBACK. Statements within it should reuse the transaction and return Ok(false) from begin(true).

The default implementation returns Ok(false) for begin(true) and an unsupported-operation error for begin(false). Its commit and rollback methods do nothing and return Ok(()).