Think API» mysql replication http://thinkapi.com/blog An interface to tech thoughts Mon, 10 May 2010 10:32:49 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 Codeigniter: Separating reads and writes for scaling MySQL http://thinkapi.com/blog/codeigniter-separating-reads-and-writes-for-scaling-mysql/ http://thinkapi.com/blog/codeigniter-separating-reads-and-writes-for-scaling-mysql/#comments Thu, 06 Aug 2009 09:41:12 +0000 Sukumar http://thinkapi.com/blog/?p=173
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    • ]]>     Generally websites average a ratio of 9:1 or more for reads:writes for their applications which makes MySQL replication as one of the ways to scale you web application. The simplest configuration is to separate reads and writes with all the reads coming from the slave servers.

    MySQL Database replication

    MySQL Database replication

    We can implement this in codeigniter using database groups.
    Below is a sample execution.

    Create two active groups – one for read and one for write.

    File: system/application/config/database.php

    $active_group = "write";
$active_record = TRUE;

$db['read']['hostname'] = "localhost";
$db['read']['username'] = "root";
$db['read']['password'] = "";
$db['read']['database'] = "read_database_name";
$db['read']['dbdriver'] = "mysql";
$db['read']['dbprefix'] = "";
$db['read']['pconnect'] = TRUE;
$db['read']['db_debug'] = FALSE;
$db['read']['cache_on'] = FALSE;
$db['read']['cachedir'] = "";
$db['read']['char_set'] = "utf8";
$db['read']['dbcollat'] = "utf8_general_ci";

$db['write']['hostname'] = "localhost";
$db['write']['username'] = "root";
$db['write']['password'] = "";
$db['write']['database'] = "write_database_name";
$db['write']['dbdriver'] = "mysql";
$db['write']['dbprefix'] = "";
$db['write']['pconnect'] = TRUE;
$db['write']['db_debug'] = FALSE;
$db['write']['cache_on'] = FALSE;
$db['write']['cachedir'] = "";
$db['write']['char_set'] = "utf8";
$db['write']['dbcollat'] = "utf8_general_ci";

    Create separate database connections to access read and write databases separately where needed (constructor is generally a good place for this).

    $read_db = $this->load->database('read', TRUE);
$write_db = $this->load->database('write', TRUE);

    You can now go about running queries in the usual way.

    /* For reads */
$query = $read_db->get('table_name');

foreach ($query->result() as $row)
{
    echo $row->title;
}

/* For writes */
$data = array(
               'title' => $title,
               'name' => $name,
               'date' => $date
            );

$write_db->insert('mytable', $data);

    In case you want to try this on an application you are already running, you can leave the “default” connection group intact and create only the “read” connection group. Use it where you think you are running read heavy queries.

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    3. Upgrading to MySQL 5.1 GA? Better Wait MySQL 5.1 General Availability has been released to the public....

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