How to use Master/Slave doctrine2 configurations from Symfony2 Console commands

Question

I'm using the Doctrine2 master/slave configuration in Symfony2 to scale my application across a single master database and several read-only (replicated) slaves.

This works perfectly from within my application and Doctrine2 sensibly uses the slave for read-only queries and the master for write operations.

If in one of my controllers, I wrote:

$em = $this->get('doctrine')->getManager();
var_dump($em->getConnection()->isConnectedToMaster());

isConnectedToMaster() returns false - which I would expect since the slave is connected to by default.

This is also the case if I run this code inside a WebTestCase

However if I wrote the exact same code inside a Symfony console command (ContainerAwareCommand):

$em = $this->getContainer()->get('doctrine')->getManager();
var_dump($em->getConnection()->isConnectedToMaster());

isConnectedToMaster() returns true. Which means the master is selected as the default.

I can't find out how to stop the default connection being master from console commands. Which means if I want to run some non-critical, heavy data processing tasks from the console - they all hit the master (bad) not one of the slaves (good).

Anyone know how I can make Doctrine2 use the slave by default from the console? Or know why it always defaults to the master?

ANSWERED: Thanks to nifr who set me on the right course - I found that my problem was because I was using JMS\JobQueueBundle (which replaces the Application used by app/console with an altered one which must connect to the MasterSlaveConnection in a way which forces the "master" to be chosen). When I commented out the

use JMS\JobQueueBundle\Console\Application;

in app/console, the slave was correctly selected in my console test.

Thanks

Answer 1

You have to make sure your command doesn't call any action that lets doctrine choose the master connection.

---

Important for the understanding of the MasterSlaveConnection should be how and when it picks the slave or master.

• picks Slave if Master was never picked before and ONLY if 'getWrappedConnection' or 'executeQuery' is used.
• Master picked when 'exec', 'executeUpdate', 'insert', 'delete', 'update', 'createSavepoint', 'releaseSavepoint', 'beginTransaction', 'rollback', 'commit', 'query' or 'prepare' is called.
• If master was picked once during the lifetime of the connection it will always get picked afterwards.
• One slave connection is randomly picked ONCE during a request.

(MasterSlaveConnection API)

Answer 2

I ended up on this question when I was looking for a way to query either my master for writting or my slaves for reading.

Here is the magic:

• Write operations (use master): $em->getConnection()->executeUpdate(...);

• Read operations (use slaves): $em->getConnection()->executeQuery(...);