Multisite Improvements with WordPress wp_get_sites() function

wp_get_sites(), is a long-awaited replacement for get_blog_list(). This function allows developers to easily get an array of all the sites on your network without resorting to a direct database query — just one of many improvements to multisite in latest version of WordPress.  wp_get_sites is located in wp-includes/ms-functions.php.

This function return an array of sites for a network or networks.

Source [ WordPress 3.8-alpha-26127 ]

function wp_get_sites( $args = array() ) {
	global $wpdb;

	if ( wp_is_large_network() )
		return array();

	$defaults = array(
		'network_id' => $wpdb->siteid,
		'public'     => null,
		'archived'   => null,
		'mature'     => null,
		'spam'       => null,
		'deleted'    => null,
		'limit'      => 100,
		'offset'     => 0,
	);

	$args = wp_parse_args( $args, $defaults );

	$query = "SELECT * FROM $wpdb->blogs WHERE 1=1 ";

	if ( isset( $args['network_id'] ) && ( is_array( $args['network_id'] ) || is_numeric( $args['network_id'] ) ) ) {
		$network_ids = implode( ',', wp_parse_id_list( $args['network_id'] ) );
		$query .= "AND site_id IN ($network_ids) ";
	}

	if ( isset( $args['public'] ) )
		$query .= $wpdb->prepare( "AND public = %d ", $args['public'] );

	if ( isset( $args['archived'] ) )
		$query .= $wpdb->prepare( "AND archived = %d ", $args['archived'] );

	if ( isset( $args['mature'] ) )
		$query .= $wpdb->prepare( "AND mature = %d ", $args['mature'] );

	if ( isset( $args['spam'] ) )
		$query .= $wpdb->prepare( "AND spam = %d ", $args['spam'] );

	if ( isset( $args['deleted'] ) )
		$query .= $wpdb->prepare( "AND deleted = %d ", $args['deleted'] );

	if ( isset( $args['limit'] ) && $args['limit'] ) {
		if ( isset( $args['offset'] ) && $args['offset'] )
			$query .= $wpdb->prepare( "LIMIT %d , %d ", $args['offset'], $args['limit'] );
		else
			$query .= $wpdb->prepare( "LIMIT %d ", $args['limit'] );
	}

	$site_results = $wpdb->get_results( $query, ARRAY_A );

	return $site_results;
}

Returns an array containing the sites in the network, or an empty array on failure. Example of the array returned you can see in the above example code.

If wp_is_large_network() returns TRUE, wp_get_sites() will return an empty array. By default wp_is_large_network() returns TRUE if there are 10,000 or more sites in your network. This can be filtered using the wp_is_large_network filter.

If you are looking for wp_get_sites alternative, returning random sites, you can find the solution on this link: wp_get_sites alternative, returning random sites