Archive for October, 2014

Migrating a Single Site from One WordPress MultiSite to Another

Tuesday, October 28th, 2014

For Developers or Power Users

Warning: This article is designed for developers, or the technically experienced.  You should be comfortable working in databases, and utilizing FTP.

Overview:

We need to move a single site from within a WordPress MultiSite to another WordPress MultiSite.  The site is completely set up, including plugins, widgets, theme options, and other settings.

We want to preserve as much of the data as possible, without hosing the complete installation.

Note: for convenience sake, we used the following terms:

Source Install – the original site, that we are moving somewhere else

Target Install – the new site location, where the source site will be moved.

Steps:

None of the import / export that we have found tools cover this scenario, so we have developed a process:

  1. Set up the new site in your Target MU Install.  Take note of the site ID (prefixed in all of the database tables).  This will be referred to as the Target Site ID.
  2. In your existing Source Install, take note of the site ID.  This will be referred to as the Source Site ID.
  3. By accessing the database (for example, using phpMyAdmin), export the tables in your Source Install.  Only export those that pertain to the single site.  They should contain the site ID, for example “wp_3_options”.
  4. Make a comprehensive list of all relevant plugins being used in your Source Install – remember, there’s “network activated” plugins as well as “site-specific” plugins.
    1. FTP the plugins from the Source Install.
    2. FTP the theme from the Source Install.
    3. IMPORTANT: Prior to uploading the database, or trying to visit the site, it’s imperative that all of the plugin / theme files exist on the Target Install.
    4. FTP the plugins and theme to the Target Install.
  5. Open the SQL export file created from step 3 above in your favorite text editor.  Update all table names to reflect the Target Site ID.  Also change them to reflect the table prefix of the Target Install.
    1. Example: if the  Source Site ID is 3, and the Target Site ID is 5, and they both use the same table prefix of “wp_”, then you would find all table names and change them according to the following model:
      1. “wp_3_options” would be updated to “wp_5_options”.
    2. If the table prefix in the Source Install is “wp_'”, and the table prefix in the Target Install is “38921_”, then the example would look like:
      1. “wp_3_options” changes to “38291_5_options”.
    3. We are only using the options table as an example.  Currently there are 9 tables in a WP MU “site”, plus there may be additional tables depending on plugins or your theme.
    4. IMPORTANT: If you aren’t familiar with table prefixes, or any of this seems off, then we recommend you consult with someone familiar with WordPress, particularly Multi Site installations.
  6. In your Source Install, run the following query on your posts table to get a listing of all media / attachments that will need to be manually moved using FTP:
    1. “SELECT * FROM `wp_3_posts` WHERE `post_type` = ‘attachment’
    2. This will list all of your attachments.  This will help you ensure that you know all of the attachments that need to get moved.
    3. Check the source wp-content/uploads folder for a “sites” sub-folder. There should be a sub-folder that is named the same as your site ID, such as wp-content/uploads/site/3.   This would be the media for your specific site.
    4. Using FTP or rsync, move the contents of the uploads folder (wp-content/uploads/sites/3) to your target install (wp-content/uploads/sites/5).
  7. Import the SQL file that you have altered into the Target Install database.

If the site domain is changing, then the following steps may be required.

  1. Run the searchreplacedb tool on the Target Install database to update the site.  Be sure to only select the tables in your migrated site – not the entire database!
  2. After running searchreplacedb tool (available here), you may need to run it again to clean up certain paths.  These may be true for image folders, particularly if the new domain has a path in it, such as :www.mydomain.com/subfolder
  3. If the site domain is changing and you are getting 404 errors when you view the site, you may need to flush the rewrite rules. In a non-MU install, this is done by going in the dashboard to the “Permalinks” page and simply clicking “Save”.  In an MU installation, the only way we are aware of is to deactivate and reactivate the theme.

Test and Tweak

As with anything, some good testing is likely in order.  We have found that the most likely place for mistakes to happen is when running the searchreplacedb tool – be sure the new urls are correct.

 

Notes for future updates:

 

Import External Images plugin

Copy / FTP files from uploads/sites/[Site_id]

run SRDB2 to update images loading from proper site ID.