Home » Database » MDB2 » Bug #10033

[2007-02-06 06:26 UTC] subwolf at gmail dot com

Description:
------------
I spent a good while this evening trying to figure out why my attempts to successfully begin and then roll back a transaction were failing, using the latest stable release with the mysqli plugin. This affects the mysql plugin also.

If you utilize MDB2::factory to instantiate a database object, and immediately follow it with a call to beginTransaction(), "SET AUTOCOMMIT = 1" is issued to the MySQL server instead of "START TRANSACTION".

By default, the driver class property start_transaction is set to FALSE, and only changes if the server version matches upon connect - which won't happen with a factory instance until a query is issued.

In this scenario, beginTransaction checks $this->start_transaction before a connection is initiated, and issues the wrong query - see test scripts. Even if the server were set by default that auto-commit mode is off, the query sent would turn it back on.

This could be fixed with a connection check like _doQuery performs (and save a re-check by passing the $connection along), or for now as simple as a note in the documentation, indicating a connection must be established first.

Test script:
---------------
Simple test:

$dsn = "mysqli://username:password@host/dbname";
$db =& MDB2::factory($dsn); // Init with factory
$db->beginTransaction(); // Returns MDB2_OK

echo $db->last_query; // "SET AUTOCOMMIT = 1"

--| MDB2/Driver/mysqli.php:229-230 |--
$query = $this->start_transaction ? 'START TRANSACTION' : 'SET AUTOCOMMIT = 1';
$result =& $this->_doQuery($query, true);
---- ----

Expected result:
----------------
$db->last_query should contain "START TRANSACTION", and subsequent queries would be within that transaction, which could then be committed or rolled back.

Actual result:
--------------
$db->last_query contains "SET AUTOCOMMIT = 1", a transaction is not initiated, and subsequent queries cannot be committed or rolled back.

[2007-02-06 06:41 UTC] subwolf at gmail dot com

I failed to mention that the server is MySQL V5.0.27, and the tables used during testing were of type InnoDB.

(Possible duplicate comment, where'd the original go!)