Multisite

@jeremyfelt

History

History as context.
b2 - Michel Valdrighi, 2001.
WordPress - early 2003
b2-smarty, then b2++ - Donncha Ó Caoimh
WordPress first release, Donncha joins dev team with goal of merge
WordPress Multi User
Automattic, WP.com work starts - WordPress MU repository
Community builds, WP.com drives primary use case.
2009, Matt announces merge
2010, January - [12602] introduces ms-settings.php
2010, WordPress 3.0 - straight no chaser.

WordPress 3.0 "Thelonious"

June 17, 2010

Use it to power one site, or 10 million.Straight, no chaser.

Structure

Context

Extension

* Provide the structure of multisite by showing what happens behind the scenes when a multisite request is made. * Empower with a sense of awareness by walking through sunrise possibilities. * Give you some immediate tips on enhancing your current multisite setup through available plugins.

wp_options
wp_posts
wp_postmeta
wp_comments
wp_commentmeta
wp_terms
wp_term_taxonomy
wp_term_relationships

wp_users
wp_usermeta

wp_options
wp_posts
wp_postmeta
wp_comments
wp_commentmeta
wp_terms
wp_term_taxonomy
wp_term_relationships

wp_users
wp_usermeta

wp_blogs
wp_blog_versions
wp_registration_log
wp_signups
wp_site
wp_sitemeta

wp_options
wp_posts
wp_postmeta
wp_comments
wp_commentmeta
wp_terms
wp_term_taxonomy
wp_term_relationships

wp_users
wp_usermeta

wp_blogs
wp_blog_versions
wp_registration_log
wp_signups
wp_site
wp_sitemeta

wp_2_options
wp_2_posts
wp_2_postmeta
wp_2_comments
wp_2_commentmeta
wp_2_terms
wp_2_term_taxonomy
wp_2_term_relationships

wp_3_options
wp_3_posts
wp_3_postmeta
wp_3_comments
wp_3_commentmeta
wp_3_terms
wp_3_term_taxonomy
wp_3_term_relationships

wp_4_options
wp_4_posts
wp_4_postmeta
wp_4_comments
wp_4_commentmeta
wp_4_terms
wp_4_term_taxonomy
wp_4_term_relationships

wp_options
wp_posts
wp_postmeta
wp_comments
wp_commentmeta
wp_terms
wp_term_taxonomy
wp_term_relationships

wp_users
wp_usermeta

wp_blogs
wp_blog_versions
wp_registration_log
wp_signups
wp_site
wp_sitemeta

wp_2_options
wp_2_posts
wp_2_postmeta
wp_2_comments
wp_2_commentmeta
wp_2_terms
wp_2_term_taxonomy
wp_2_term_relationships

wp_3_options
wp_3_posts
wp_3_postmeta
wp_3_comments
wp_3_commentmeta
wp_3_terms
wp_3_term_taxonomy
wp_3_term_relationships

wp_4_options
wp_4_posts
wp_4_postmeta
wp_4_comments
wp_4_commentmeta
wp_4_terms
wp_4_term_taxonomy
wp_4_term_relationships

wp_5_options
wp_5_posts
wp_5_postmeta
wp_5_comments
wp_5_commentmeta
wp_5_terms
wp_5_term_taxonomy
wp_5_term_relationships

wp_6_options
wp_6_posts
wp_6_postmeta
wp_6_comments
wp_6_commentmeta
wp_6_terms
wp_6_term_taxonomy
wp_6_term_relationships

wp_7_options
wp_7_posts
wp_7_postmeta
wp_7_comments
wp_7_commentmeta
wp_7_terms
wp_7_term_taxonomy
wp_7_term_relationships

wp_options
wp_posts
wp_postmeta
wp_comments
wp_commentmeta
wp_terms
wp_term_taxonomy
wp_term_relationships

wp_users
wp_usermeta

wp_blogs
wp_blog_versions
wp_registration_log
wp_signups
wp_site
wp_sitemeta

wp_2_options
wp_2_posts
wp_2_postmeta
wp_2_comments
wp_2_commentmeta
wp_2_terms
wp_2_term_taxonomy
wp_2_term_relationships

wp_3_options
wp_3_posts
wp_3_postmeta
wp_3_comments
wp_3_commentmeta
wp_3_terms
wp_3_term_taxonomy
wp_3_term_relationships

wp_4_options
wp_4_posts
wp_4_postmeta
wp_4_comments
wp_4_commentmeta
wp_4_terms
wp_4_term_taxonomy
wp_4_term_relationships

wp_5_options
wp_5_posts
wp_5_postmeta
wp_5_comments
wp_5_commentmeta
wp_5_terms
wp_5_term_taxonomy
wp_5_term_relationships

wp_6_options
wp_6_posts
wp_6_postmeta
wp_6_comments
wp_6_commentmeta
wp_6_terms
wp_6_term_taxonomy
wp_6_term_relationships

wp_7_options
wp_7_posts
wp_7_postmeta
wp_7_comments
wp_7_commentmeta
wp_7_terms
wp_7_term_taxonomy
wp_7_term_relationships

wp_8_options
wp_8_posts
wp_8_postmeta
wp_8_comments
wp_8_commentmeta
wp_8_terms
wp_8_term_taxonomy
wp_8_term_relationships

wp_9_options
wp_9_posts
wp_9_postmeta
wp_9_comments
wp_9_commentmeta
wp_9_terms
wp_9_term_taxonomy
wp_9_term_relationships

wp_10_options
wp_10_posts
wp_10_postmeta
wp_10_comments
wp_10_commentmeta
wp_10_terms
wp_10_term_taxonomy
wp_10_term_relationships

wp_11_options
wp_11_posts
wp_11_postmeta
wp_11_comments
wp_11_commentmeta
wp_11_terms
wp_11_term_taxonomy
wp_11_term_relationships

wp_12_options
wp_12_posts
wp_12_postmeta
wp_12_comments
wp_12_commentmeta
wp_12_terms
wp_12_term_taxonomy
wp_12_term_relationships

wp_13_options
wp_13_posts
wp_13_postmeta
wp_13_comments
wp_13_commentmeta
wp_13_terms
wp_13_term_taxonomy
wp_13_term_relationships

wp_14_options
wp_14_posts
wp_14_postmeta
wp_14_comments
wp_14_commentmeta
wp_14_terms
wp_14_term_taxonomy
wp_14_term_relationships

wp_options
wp_posts
wp_postmeta
wp_comments
wp_commentmeta
wp_terms
wp_term_taxonomy
wp_term_relationships

wp_users
wp_usermeta

wp_blogs
wp_blog_versions
wp_registration_log
wp_signups
wp_site
wp_sitemeta

wp_2_options
wp_2_posts
wp_2_postmeta
wp_2_comments
wp_2_commentmeta
wp_2_terms
wp_2_term_taxonomy
wp_2_term_relationships

wp_3_options
wp_3_posts
wp_3_postmeta
wp_3_comments
wp_3_commentmeta
wp_3_terms
wp_3_term_taxonomy
wp_3_term_relationships

wp_4_options
wp_4_posts
wp_4_postmeta
wp_4_comments
wp_4_commentmeta
wp_4_terms
wp_4_term_taxonomy
wp_4_term_relationships

wp_5_options
wp_5_posts
wp_5_postmeta
wp_5_comments
wp_5_commentmeta
wp_5_terms
wp_5_term_taxonomy
wp_5_term_relationships

wp_6_options
wp_6_posts
wp_6_postmeta
wp_6_comments
wp_6_commentmeta
wp_6_terms
wp_6_term_taxonomy
wp_6_term_relationships

wp_7_options
wp_7_posts
wp_7_postmeta
wp_7_comments
wp_7_commentmeta
wp_7_terms
wp_7_term_taxonomy
wp_7_term_relationships

wp_8_options
wp_8_posts
wp_8_postmeta
wp_8_comments
wp_8_commentmeta
wp_8_terms
wp_8_term_taxonomy
wp_8_term_relationships

wp_9_options
wp_9_posts
wp_9_postmeta
wp_9_comments
wp_9_commentmeta
wp_9_terms
wp_9_term_taxonomy
wp_9_term_relationships

wp_10_options
wp_10_posts
wp_10_postmeta
wp_10_comments
wp_10_commentmeta
wp_10_terms
wp_10_term_taxonomy
wp_10_term_relationships

wp_11_options
wp_11_posts
wp_11_postmeta
wp_11_comments
wp_11_commentmeta
wp_11_terms
wp_11_term_taxonomy
wp_11_term_relationships

wp_12_options
wp_12_posts
wp_12_postmeta
wp_12_comments
wp_12_commentmeta
wp_12_terms
wp_12_term_taxonomy
wp_12_term_relationships

wp_13_options
wp_13_posts
wp_13_postmeta
wp_13_comments
wp_13_commentmeta
wp_13_terms
wp_13_term_taxonomy
wp_13_term_relationships

wp_14_options
wp_14_posts
wp_14_postmeta
wp_14_comments
wp_14_commentmeta
wp_14_terms
wp_14_term_taxonomy
wp_14_term_relationships

wp_15_options
wp_15_posts
wp_15_postmeta
wp_15_comments
wp_15_commentmeta
wp_15_terms
wp_15_term_taxonomy
wp_15_term_relationships

wp_16_options
wp_16_posts
wp_16_postmeta
wp_16_comments
wp_16_commentmeta
wp_16_terms
wp_16_term_taxonomy
wp_16_term_relationships

wp_17_options
wp_17_posts
wp_17_postmeta
wp_17_comments
wp_17_commentmeta
wp_17_terms
wp_17_term_taxonomy
wp_17_term_relationships

wp_18_options
wp_18_posts
wp_18_postmeta
wp_18_comments
wp_18_commentmeta
wp_18_terms
wp_18_term_taxonomy
wp_18_term_relationships

wp_19_options
wp_19_posts
wp_19_postmeta
wp_19_comments
wp_19_commentmeta
wp_19_terms
wp_19_term_taxonomy
wp_19_term_relationships

wp_20_options
wp_20_posts
wp_20_postmeta
wp_20_comments
wp_20_commentmeta
wp_20_terms
wp_20_term_taxonomy
wp_20_term_relationships

wp_21_options
wp_21_posts
wp_21_postmeta
wp_21_comments
wp_21_commentmeta
wp_21_terms
wp_21_term_taxonomy
wp_21_term_relationships

wp_22_options
wp_22_posts
wp_22_postmeta
wp_22_comments
wp_22_commentmeta
wp_22_terms
wp_22_term_taxonomy
wp_22_term_relationships

wp_23_options
wp_23_posts
wp_23_postmeta
wp_23_comments
wp_23_commentmeta
wp_23_terms
wp_23_term_taxonomy
wp_23_term_relationships

Multisite is basically using the global blogs and sites tables to figure out what other set of tables to use for the request. After that, almost everything it does is exactly the same as single site for most page loads. Remember this as it's key to understanding many things in multisite and we'll touch on it again later.

Network: $current_site

$current_site->id;        // The ID of the network in the wp_site table.
$current_site->domain;
$current_site->path;      // Uses leading and trailing slashes - '/path/'
$current_site->blog_id;   // The blog_id of the network's main site.

mysql> SELECT * FROM wp_site;
+----+---------------------------+------+
| id | domain                    | path |
+----+---------------------------+------+
|  1 | jeremyfelt.com            | /    |
+----+---------------------------+------+
1 row in set (0.00 sec)

Site: $current_blog

$current_blog->blog_id; // The ID of the site in the wp_blogs table.
$current_blog->site_id; // The ID of the site's network in the wp_site table.
$current_blog->domain;
$current_blog->path;    // Uses leading and trailing slashes - '/path/'
$current_blog->....     // More data directly from the wp_blogs record.

mysql> SELECT blog_id, site_id, domain, path FROM wp_blogs;
+---------+---------+----------------+----------+
| blog_id | site_id | domain         | path     |
+---------+---------+----------------+----------+
|       1 |       1 | jeremyfelt.com | /        |
|       2 |       1 | jeremyfelt.com | /photos/ |
+---------+---------+----------------+----------+
2 rows in set (0.00 sec)

get_site_by_path()

/**
 * Retrieve a site object by its domain and path.
 *
 * @param string   $domain   Domain to check.
 * @param string   $path     Path to check.
 * @param int|null $segments Path segments to use.
 */
function get_site_by_path( $domain, $path, $segments = null ) {

  // Use $wpdb to find matching site data from wp_blogs
  $site = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->blogs 
    WHERE domain = %s AND path = %s", $domains[0], $paths[0] ) );

}

get_network_by_path()

/**
 * Retrieve a network object by its domain and path.
 *
 * @param string   $domain   Domain to check.
 * @param string   $path     Path to check.
 * @param int|null $segments Path segments to use.
 */
function get_network_by_path( $domain, $path, $segments = null ) {

  // Use $wpdb to find matching network data from wp_site
  $networks = $wpdb->get_results( "SELECT id, domain, path FROM $wpdb->site
    WHERE domain IN ($search_domains) AND path IN ($search_paths)
    ORDER BY CHAR_LENGTH(domain) DESC, CHAR_LENGTH(path) DESC" );

}

wp-includes/ms-settings.php

$domain = strtolower( stripslashes( $_SERVER['HTTP_HOST'] ) );

if ( substr( $domain, -3 ) == ':80' ) {
	$domain = substr( $domain, 0, -3 );
	$_SERVER['HTTP_HOST'] = substr( $_SERVER['HTTP_HOST'], 0, -3 );
} elseif ( substr( $domain, -4 ) == ':443' ) {
	$domain = substr( $domain, 0, -4 );
	$_SERVER['HTTP_HOST'] = substr( $_SERVER['HTTP_HOST'], 0, -4 );
}

$path = stripslashes( $_SERVER['REQUEST_URI'] );

if ( is_admin() ) {
	$path = preg_replace( '#(.*)/wp-admin/.*#', '$1/', $path );
}
list( $path ) = explode( '?', $path );

wp-includes/ms-settings.php

if ( defined( 'DOMAIN_CURRENT_SITE' ) && defined( 'PATH_CURRENT_SITE' ) ) {

  $current_site = new stdClass;
  $current_site->id = defined( 'SITE_ID_CURRENT_SITE' ) ? SITE_ID_CURRENT_SITE : 1;
  $current_site->domain = DOMAIN_CURRENT_SITE;
  $current_site->path = PATH_CURRENT_SITE;

  if ( defined( 'BLOG_ID_CURRENT_SITE' ) ) {
    $current_site->blog_id = BLOG_ID_CURRENT_SITE;
  }

wp-config.php

define( 'DOMAIN_CURRENT_SITE', 'jeremyfelt.com' );
define( 'PATH_CURRENT_SITE',   '/'              );
define( 'SITE_ID_CURRENT_SITE', 1               );
define( 'BLOG_ID_CURRENT_SITE', 1               );

This configuration cares nothing for whether this is a subdirectory or subdomain installation of multisite.

Subdirectory Configuration

All sites on a network have the same domain and different paths

Populate $current_site first

If more than one network exists, use get_network_by_path()

Populate $current_blog using get_site_by_path()

mysql> SELECT blog_id, site_id, domain, path FROM wp_blogs;
+---------+---------+----------------+----------+
| blog_id | site_id | domain         | path     |
+---------+---------+----------------+----------+
|       1 |       1 | jeremyfelt.com | /        |
|       2 |       1 | jeremyfelt.com | /photos/ |
+---------+---------+----------------+----------+
2 rows in set (0.00 sec)

Subdomain Configuration

Sites on a network have different subdomains

Sites can also have different paths

Populate $current_blog first using get_site_by_path()

Populate $current_site using the site_id attached to the $current_blog object

mysql> SELECT blog_id, site_id, domain, path FROM wp_blogs;
+---------+---------+-----------------------+----------+
| blog_id | site_id | domain                | path     |
+---------+---------+-----------------------+----------+
|       1 |       1 | jeremyfelt.com        | /        |
|       2 |       1 | photos.jeremyfelt.com | /        |
|       3 |       2 | alsoadomain.com       | /howdy/  |
+---------+---------+-----------------------+----------+
3 rows in set (0.00 sec)

wp_options
wp_posts
wp_postmeta
wp_comments
wp_commentmeta
wp_terms
wp_term_taxonomy
wp_term_relationships

wp_users
wp_usermeta

wp_blogs
wp_blog_versions
wp_registration_log
wp_signups
wp_site
wp_sitemeta

wp_2_options
wp_2_posts
wp_2_postmeta
wp_2_comments
wp_2_commentmeta
wp_2_terms
wp_2_term_taxonomy
wp_2_term_relationships

wp_3_options
wp_3_posts
wp_3_postmeta
wp_3_comments
wp_3_commentmeta
wp_3_terms
wp_3_term_taxonomy
wp_3_term_relationships

wp_4_options
wp_4_posts
wp_4_postmeta
wp_4_comments
wp_4_commentmeta
wp_4_terms
wp_4_term_taxonomy
wp_4_term_relationships

wp_5_options
wp_5_posts
wp_5_postmeta
wp_5_comments
wp_5_commentmeta
wp_5_terms
wp_5_term_taxonomy
wp_5_term_relationships

wp_6_options
wp_6_posts
wp_6_postmeta
wp_6_comments
wp_6_commentmeta
wp_6_terms
wp_6_term_taxonomy
wp_6_term_relationships

wp_7_options
wp_7_posts
wp_7_postmeta
wp_7_comments
wp_7_commentmeta
wp_7_terms
wp_7_term_taxonomy
wp_7_term_relationships

wp_8_options
wp_8_posts
wp_8_postmeta
wp_8_comments
wp_8_commentmeta
wp_8_terms
wp_8_term_taxonomy
wp_8_term_relationships

wp_9_options
wp_9_posts
wp_9_postmeta
wp_9_comments
wp_9_commentmeta
wp_9_terms
wp_9_term_taxonomy
wp_9_term_relationships

wp_10_options
wp_10_posts
wp_10_postmeta
wp_10_comments
wp_10_commentmeta
wp_10_terms
wp_10_term_taxonomy
wp_10_term_relationships

wp_11_options
wp_11_posts
wp_11_postmeta
wp_11_comments
wp_11_commentmeta
wp_11_terms
wp_11_term_taxonomy
wp_11_term_relationships

wp_12_options
wp_12_posts
wp_12_postmeta
wp_12_comments
wp_12_commentmeta
wp_12_terms
wp_12_term_taxonomy
wp_12_term_relationships

wp_13_options
wp_13_posts
wp_13_postmeta
wp_13_comments
wp_13_commentmeta
wp_13_terms
wp_13_term_taxonomy
wp_13_term_relationships

wp_14_options
wp_14_posts
wp_14_postmeta
wp_14_comments
wp_14_commentmeta
wp_14_terms
wp_14_term_taxonomy
wp_14_term_relationships

wp_15_options
wp_15_posts
wp_15_postmeta
wp_15_comments
wp_15_commentmeta
wp_15_terms
wp_15_term_taxonomy
wp_15_term_relationships

wp_16_options
wp_16_posts
wp_16_postmeta
wp_16_comments
wp_16_commentmeta
wp_16_terms
wp_16_term_taxonomy
wp_16_term_relationships

wp_17_options
wp_17_posts
wp_17_postmeta
wp_17_comments
wp_17_commentmeta
wp_17_terms
wp_17_term_taxonomy
wp_17_term_relationships

wp_18_options
wp_18_posts
wp_18_postmeta
wp_18_comments
wp_18_commentmeta
wp_18_terms
wp_18_term_taxonomy
wp_18_term_relationships

wp_19_options
wp_19_posts
wp_19_postmeta
wp_19_comments
wp_19_commentmeta
wp_19_terms
wp_19_term_taxonomy
wp_19_term_relationships

wp_20_options
wp_20_posts
wp_20_postmeta
wp_20_comments
wp_20_commentmeta
wp_20_terms
wp_20_term_taxonomy
wp_20_term_relationships

wp_21_options
wp_21_posts
wp_21_postmeta
wp_21_comments
wp_21_commentmeta
wp_21_terms
wp_21_term_taxonomy
wp_21_term_relationships

wp_22_options
wp_22_posts
wp_22_postmeta
wp_22_comments
wp_22_commentmeta
wp_22_terms
wp_22_term_taxonomy
wp_22_term_relationships

wp_23_options
wp_23_posts
wp_23_postmeta
wp_23_comments
wp_23_commentmeta
wp_23_terms
wp_23_term_taxonomy
wp_23_term_relationships

wp_usermeta

mysql> SELECT * FROM wp_usermeta WHERE meta_key LIKE '%_capabilities';
+----------+---------+-------------------+---------------------------------+
| umeta_id | user_id | meta_key          | meta_value                      |
+----------+---------+-------------------+---------------------------------+
|       10 |       1 | wp_capabilities   | a:1:{s:13:"administrator";b:1;} |
|       32 |       2 | wp_capabilities   | a:1:{s:13:"administrator";b:1;} |
|       47 |       1 | wp_2_capabilities | a:1:{s:13:"administrator";b:1;} |
|       54 |       2 | wp_2_capabilities | a:1:{s:11:"contributor";b:1;}   |
|       58 |       3 | wp_2_capabilities | a:1:{s:6:"editor";b:1;}         |
|       60 |       3 | wp_capabilities   | a:1:{s:6:"author";b:1;}         |
+----------+---------+-------------------+---------------------------------+
6 rows in set (0.00 sec)

wp-includes/ms-settings.php

/** Include Multisite initialization functions */
require_once( ABSPATH . WPINC . '/ms-load.php' );
require_once( ABSPATH . WPINC . '/ms-default-constants.php' );

if ( defined( 'SUNRISE' ) ) {
	// Load custom logic to find a network and site.
	include_once( WP_CONTENT_DIR . '/sunrise.php' );
}

ms_subdomain_constants();

if ( !isset( $current_site ) || !isset( $current_blog ) ) {
	// Default core logic to find a network and site.
}

$wpdb->set_prefix( $table_prefix, false );
$wpdb->set_blog_id( $current_blog->blog_id, $current_blog->site_id );
$table_prefix = $wpdb->get_blog_prefix();

sunrise allows you to hook in before anything else is done in WordPress and determine what this page load will become. This is where you can do very custom, purposeful things that could normally be handled further down in the stack (nginx config) or up in the stack (WordPress plugin.)

wp-content/sunrise.php

//Capture the domain and path from the current request
$req_domain    = $_SERVER['HTTP_HOST'];
$req_uri       = trim( $_SERVER['REQUEST_URI'], '/' );

// We currently support one subdirectory deep, and therefore
// only look at the first path level.
$req_uri_parts = explode( '/', $req_uri );
$req_path = $req_uri_parts[0] . '/';

wp_cache_add_global_groups( 'wsuwp:network' );
wp_cache_add_global_groups( 'wsuwp:site' );

// If we're dealing with a root domain, we want to leave it
// at a path of '/'
if ( '/' !== $req_path ) {
	$req_path = '/' . $req_path;
}

if ( ! $current_blog = wp_cache_get( $req_domain . $req_path, 'wsuwp:site' ) ) {

Caching the request makes all future lookups easy. We clear the cache for a domain/path combination whenever a new site is created, and conflicts are less possible the other way around - when a page is created.

wp-content/sunrise.php

// Start with the assumption that SSL is available for this domain.
$current_blog->ssl_enabled = true;
// We're looking for a base option name of foo.bar.com_ssl_disabled
$ssl_domain_check = $requested_domain . '_ssl_disabled';
$non_ssl_domain = $wpdb->get_row( $wpdb->prepare( "SELECT option_id FROM [...]" ) );

if ( is_object( $non_ssl_domain ) ) {
	$current_blog->ssl_enabled = false;
}

wp_cache_add( $req_domain . $req_path, $current_blog, 'wsuwp:site', 60 * 60 * 12 );

if ( isset( $current_blog->ssl_enabled ) && true === $current_blog->ssl_enabled ) {
	define( 'FORCE_SSL_ADMIN', true );
	define( 'FORCE_SSL_LOGIN', true );
}

We also check to see if the domain supports HTTPS. We assume by default that it does and then do a quick lookup to determine if it has been flagged as not having a cert yet.

Context

switch_to_blog( $id )

$GLOBALS['_wp_switched_stack'][] = $GLOBALS['blog_id'];
// ...
$GLOBALS['switched'] = true;

Store a record of the current context in an array that we can walk back through.

switch_to_blog( $id )

$wpdb->set_blog_id( $new_blog );
$GLOBALS['table_prefix'] = $wpdb->get_blog_prefix();
$prev_blog_id = $GLOBALS['blog_id'];
$GLOBALS['blog_id'] = $new_blog;

Context changes:

$blog_id property of $wpdb
Database table prefix used by $wpdb to wp_#_ from wp_
Global $blog_id

switch_to_blog( $id )

wp_cache_init();
wp_cache_add_global_groups( $global_groups );
wp_cache_add_non_persistent_groups( array( ... ) );

Context changes:

Uses the global $table_prefix to reinitialize object cache with keys for the switched site.

switch_to_blog( $id )

$wp_roles->reinit();
$current_user = wp_get_current_user();
$current_user->for_blog( $new_blog );

Context changes:

Uses $wpdb->get_blog_prefix() to set a prefix for grabbing wp_#_user_roles from get_option()

switch_to_blog( $id )

// Delete the rewrite_rules option from
// the switched site. Good!
delete_option( 'rewrite_rules' );

// Build the permalink structure in the
// context of the main site. Bad!
$this->rewrite_rules();

// Update the rewrite_rules option for the
// switched site. Horrible!
update_option( 'rewrite_rules', $this->rules );

Does not change the context of rewrite rules.

https://jeremyfelt.com/multisite-rewrite-rules/

switch_to_blog( $id )

Does not change the context of code.

Only the theme and plugins activated for the original site will be available.

restore_current_blog()

if ( empty( $GLOBALS['_wp_switched_stack'] ) )
	return false;

$blog = array_pop( $GLOBALS['_wp_switched_stack'] );

// ...

$wpdb->set_blog_id( $blog );
$prev_blog_id = $GLOBALS['blog_id'];
$GLOBALS['blog_id'] = $blog;
$GLOBALS['table_prefix'] = $wpdb->get_blog_prefix();

Restore context to the last used site via $GLOBALS['_wp_switched_stack'].

Using the global _wp_switched_stack WP maintains, we're able to switch back down to where we started. Can be useful to loop this until it returns false.

ms_is_switched()

// Loop until $GLOBALS['_wp_switched_stack'] is clear.
while ( ms_is_switched() ) {
	restore_current_blog();
}

Determine if context is switched and when we're back to normal.

is_main_site()

function is_main_site( $site_id = null ) {
	// This is the current network's information
	global $current_site;

	if ( ! is_multisite() )
		return true;

	if ( ! $site_id )
		$site_id = get_current_blog_id();

	return (int) $site_id === (int) $current_site->blog_id;
}

is_main_network()

function is_main_network( $network_id = null ) {
    $current_network_id = (int) get_current_site()->id;

    if ( ! $network_id )
      $network_id = $current_network_id;

    if ( defined( 'PRIMARY_NETWORK_ID' ) )
      return $network_id === (int) PRIMARY_NETWORK_ID;

    if ( 1 === $current_network_id )
      return $network_id === $current_network_id;

    if ( $primary_network_id )
      return $network_id === $primary_network_id;

    $primary_network_id = $wpdb->get_var( "SELECT id FROM $wpdb->site..." );

    return $network_id === $primary_network_id;
}

get_main_network_id() will be available in 4.3

get_blog_details()

get_current_site()

Extension

Must Use Plugins

wp-content/mu-plugins/

Domain "Mapping"

Mercator - https://github.com/humanmade/Mercator

Multiple Networks

WP Multi Network - https://wordpress.org/plugins/wp-multi-network/

HyperDB

https://wordpress.org/plugins/hyperdb/

wp_options
wp_posts
wp_postmeta
wp_comments
wp_commentmeta
wp_terms
wp_term_taxonomy
wp_term_relationships

wp_users
wp_usermeta

wp_blogs
wp_blog_versions
wp_registration_log
wp_signups
wp_site
wp_sitemeta

wp_2_options
wp_2_posts
wp_2_postmeta
wp_2_comments
wp_2_commentmeta
wp_2_terms
wp_2_term_taxonomy
wp_2_term_relationships

wp_3_options
wp_3_posts
wp_3_postmeta
wp_3_comments
wp_3_commentmeta
wp_3_terms
wp_3_term_taxonomy
wp_3_term_relationships

wp_4_options
wp_4_posts
wp_4_postmeta
wp_4_comments
wp_4_commentmeta
wp_4_terms
wp_4_term_taxonomy
wp_4_term_relationships

wp_5_options
wp_5_posts
wp_5_postmeta
wp_5_comments
wp_5_commentmeta
wp_5_terms
wp_5_term_taxonomy
wp_5_term_relationships

wp_6_options
wp_6_posts
wp_6_postmeta
wp_6_comments
wp_6_commentmeta
wp_6_terms
wp_6_term_taxonomy
wp_6_term_relationships

wp_7_options
wp_7_posts
wp_7_postmeta
wp_7_comments
wp_7_commentmeta
wp_7_terms
wp_7_term_taxonomy
wp_7_term_relationships

wp_8_options
wp_8_posts
wp_8_postmeta
wp_8_comments
wp_8_commentmeta
wp_8_terms
wp_8_term_taxonomy
wp_8_term_relationships

wp_9_options
wp_9_posts
wp_9_postmeta
wp_9_comments
wp_9_commentmeta
wp_9_terms
wp_9_term_taxonomy
wp_9_term_relationships

wp_10_options
wp_10_posts
wp_10_postmeta
wp_10_comments
wp_10_commentmeta
wp_10_terms
wp_10_term_taxonomy
wp_10_term_relationships

wp_11_options
wp_11_posts
wp_11_postmeta
wp_11_comments
wp_11_commentmeta
wp_11_terms
wp_11_term_taxonomy
wp_11_term_relationships

wp_12_options
wp_12_posts
wp_12_postmeta
wp_12_comments
wp_12_commentmeta
wp_12_terms
wp_12_term_taxonomy
wp_12_term_relationships

wp_13_options
wp_13_posts
wp_13_postmeta
wp_13_comments
wp_13_commentmeta
wp_13_terms
wp_13_term_taxonomy
wp_13_term_relationships

wp_14_options
wp_14_posts
wp_14_postmeta
wp_14_comments
wp_14_commentmeta
wp_14_terms
wp_14_term_taxonomy
wp_14_term_relationships

wp_15_options
wp_15_posts
wp_15_postmeta
wp_15_comments
wp_15_commentmeta
wp_15_terms
wp_15_term_taxonomy
wp_15_term_relationships

wp_16_options
wp_16_posts
wp_16_postmeta
wp_16_comments
wp_16_commentmeta
wp_16_terms
wp_16_term_taxonomy
wp_16_term_relationships

wp_17_options
wp_17_posts
wp_17_postmeta
wp_17_comments
wp_17_commentmeta
wp_17_terms
wp_17_term_taxonomy
wp_17_term_relationships

wp_18_options
wp_18_posts
wp_18_postmeta
wp_18_comments
wp_18_commentmeta
wp_18_terms
wp_18_term_taxonomy
wp_18_term_relationships

Object Caching

Future

WP_Site, WP_Network, WP_Site_Query, WP_Network_Query
Improved network admin UI/UX
Established network types

Multisite

Office Hours: Tuesday, 20:00 UTC in #core-multisite

Slides: jeremyfelt.com/wcyvr-2015/

@jeremyfelt

Multisite @jeremyfelt

Multisite

jeremyfelt

Multisite

0 0 (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/platform.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

Multisite-Talk

Multisite

History

WordPress 3.0 "Thelonious"

Structure

Context

Extension

Network: $current_site

Site: $current_blog

get_site_by_path()

get_network_by_path()

wp-includes/ms-settings.php

wp-includes/ms-settings.php

wp-config.php

Subdirectory Configuration

Subdomain Configuration

wp_usermeta

wp-includes/ms-settings.php

wp-content/sunrise.php

wp-content/sunrise.php

Context

switch_to_blog( $id )

switch_to_blog( $id )

switch_to_blog( $id )

switch_to_blog( $id )

switch_to_blog( $id )

switch_to_blog( $id )

switch_to_blog( $id )

restore_current_blog()

ms_is_switched()

is_main_site()

is_main_network()

get_blog_details()

get_current_site()

Extension

Must Use Plugins

Domain "Mapping"

Multiple Networks

HyperDB

Object Caching

Future

Multisite

0 0