gistfile1.xml

<monolog:config>
    <monolog:handlers>
        <monolog:handler name="main" type="stream" path="/var/log/symfony.log">
            <monolog:channels>
                <channel>!doctrine</channel>
            </monolog:channels>
        </monolog:handler>

        <monolog:handler name="doctrine" type="stream" path="/var/log/doctrine.log" />
            <monolog:channels>
                <channel>doctrine</channel>
            </monolog:channels>
        </monolog:handler>
    </monolog:handlers>
</monolog:config>