API support for transactions
API support for transactions
API support for transactions
The MySQL server supports transactions depending on
the storage engine used. Since MySQL 5.5, the default storage
engine is InnoDB. InnoDB has full ACID transaction support.
Transactions can either be controlled using SQL or
API calls. It is recommended to use API calls for enabling and
disabling the auto commit mode and for committing and rolling back
transactions.
Example #1 Setting auto commit mode with SQL and through
the API
<?php
$mysqli = new mysqli("example.com", "user", "password", "database");
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
}
/* Recommended: using API to control transactional settings */
$mysqli->autocommit(false);
/* Won't be monitored and recognized by the replication and the load balancing plugin */
if (!$mysqli->query('SET AUTOCOMMIT = 0')) {
echo "Query failed: (" . $mysqli->errno . ") " . $mysqli->error;
}
?>
Optional feature packages, such as the replication
and load balancing plugin, can easily monitor API calls. The
replication plugin offers transaction aware load balancing, if
transactions are controlled with API calls. Transaction aware load
balancing is not available if SQL statements are used for setting
auto commit mode, committing or rolling back a transaction.
Example #2 Commit and rollback
<?php
$mysqli = new mysqli("example.com", "user", "password", "database");
$mysqli->autocommit(false);
$mysqli->query("INSERT INTO test(id) VALUES (1)");
$mysqli->rollback();
$mysqli->query("INSERT INTO test(id) VALUES (2)");
$mysqli->commit();
?>
Please note, that the MySQL server cannot roll back
all statements. Some statements cause an implicit commit.
See also
- mysqli::autocommit()
- mysqli_result::commit()
- mysqli_result::rollback()