Changed to allow replication connection

Question

This change allows replication connection.

When you want to use replication feature, you can set the flag in db.php.

 php
<?php return array(
    'default' => array(
        'connection'  => array(
            'dsn'        => 'mysql:host=localhost;dbname=default',
            'username'   => 'dbuser',
            'password'   => 'dbpass',
        ),
    ),
    'db1' => array(
        'type'        => 'pdo',
        'connection'  => array(
            'dsn'        => 'mysql:host=localhost;dbname=db1',
            'username'   => 'dbuser',
            'password'   => 'dbpass',
        ),
        'identifier'   => '`',
        'table_prefix' => '',
        'charset'      => 'utf8',
        'enable_cache' => true,
        'profiling'    => false,
    ),
    'db2' => array(
        'type'        => 'pdo',
        'connection'  => array(
            'dsn'        => 'mysql:host=localhost;dbname=db2',
            'username'   => 'dbuser',
            'password'   => 'dbpass',
        ),
        'identifier'   => '`',
        'table_prefix' => '',
        'charset'      => 'utf8',
        'enable_cache' => true,
        'profiling'    => false,
    ),
    'replication' => array(
        'enable' => true,
        'master' => array('db1'),
        'slave' => array('db1', 'db2'),
    )
);

Only Database_Query_Builder_Select uses the slave connection. And other queries use the master connection.

Respectively, specify the multiple connection name, the destination is a random lottery.

I want your opinion.

该提问来源于开源项目：fuel/core