Too Many Connections w/ Laravel 4 and MySQL

Question

I have a question about handling multiple DB connections in Laravel 4.1. Say I have one DB host with 3 DBs on that host

eg:

    'mysql' => array(
        'driver'    => 'mysql',
        'host'      => 'localhost',
        'database'  => 'DB_1',
        'username'  => $_ENV['MYSQL_USER'],
        'password'  => $_ENV['MYSQL_PASS'],
        'charset'   => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix'    => '',
    ),

    'mysql2' => array(
        'driver'    => 'mysql',
        'host'      => 'localhost',
        'database'  => 'DB_2',
        'username'  => $_ENV['MYSQL_USER'],
        'password'  => $_ENV['MYSQL_PASS'],
        'charset'   => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix'    => '',
    ),

    'mysql3' => array(
        'driver'    => 'mysql',
        'host'      => 'localhost',
        'database'  => 'DB_3',
        'username'  => $_ENV['MYSQL_USER'],
        'password'  => $_ENV['MYSQL_PASS'],
        'charset'   => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix'    => '',
    ),

Should I be making 3 different connections to those DBs?

Or should I simply have one connection and in each model specify the table name to something like:

public $table = "DB_2.table_name";

The reason I ask, is that I have noticed that I it is easier to exhaust the database connections as it creates a new DB connection when ever it needs to connect to a different database.

I know both will work, but I'm interested in what is considered to be "best practice" in this sort of situation.

Thanks in advance for the feedback.

Cheers.

Answer 1

Specify to the table, not the DB implementation.

I'm not a big fan of the 'feature' that allows cross DB querying on MySQL between DB's on the same server. This is what would allow the thing you mention.

• If you change the name of your db you'll need to refactor your table names in your code.
• If you create a test db like table_name_test to test your code or a db modification, you'll have to modify all your tables tames in your code each time you jump between db's vs. just editing the config file.
• What if you move to a differnt DB technology without DB names (one Db per server/fuile, you'll need to refactor your table name properties in each class)
• It leads down the dark, tempting yet vile path of cross db queries like select * from db1.foo f Join db2.bar b on b.id = f.id;. Congratulations you just turned your 2 dbs into actually one big db that might not run outside MySQL

Also, even though you're specifying three connections, you're probably not making a connection and using all three at once... I hope. If you do use all 3 connection per request to you laravel app/site saving 2 connections is probably, micro optimization.

Answer 2

This code made the trick for me when I needed.

Config::set('database.default', 'database_name');

In your case, replace the database_name with the ones you may need. I call it in the controller each time I see a need to make the switch. Before a query, for exemple.

I don't know if is the best way ever to do it, but it worked for me and I thought it worth sharing! =D