Doctrine_manual-1-2-en

Chapter 21: Transactions 307
try {
$conn->beginTransaction();
// do some operations here
// creates a new savepoint called mysavepoint
$conn->beginTransaction('mysavepoint');
// do some operations here
$conn->commit(); // deletes all savepoints
} catch(Exception $e) {
$conn->rollback(); // deletes all savepoints
}
Isolation Levels
A transaction isolation level sets the default transactional behavior. As the name 'isolation
level' suggests, the setting determines how isolated each transation is, or what kind of locks
are associated with queries inside a transaction. The four available levels are (in ascending
order of strictness):
READ UNCOMMITTED
Barely transactional, this setting allows for so-called 'dirty reads', where queries inside
one transaction are affected by uncommitted changes in another transaction.
READ COMMITTED
Committed updates are visible within another transaction. This means identical queries
within a transaction can return differing results. This is the default in some DBMS's.
REPEATABLE READ
Within a transaction, all reads are consistent. This is the default of Mysql INNODB
engine.
SERIALIZABLE
Updates are not permitted in other transactions if a transaction has run an ordinary
SELECT query.
To get the transaction module use the following code:
$tx = $conn->transaction;
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Set the isolation level to READ COMMITTED:
$tx->setIsolation('READ COMMITTED');
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Set the isolation level to SERIALIZABLE:
$tx->setIsolation('SERIALIZABLE');
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Some drivers (like Mysql) support the fetching of current transaction isolation level. It can
be done as follows:
$level = $tx->getIsolation();
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