Share certain tables of a WP database over 2 domains

This thread should be helpful; it’s not a plugin but some code to work with.

found the solution here

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Nevermind, I think I found it thanks top this site :
https://www.wiseontech.com/hack/wordpress-hacking-multiple-blogs-on-one-set-of-tables-2

Down in the comments they refer to more modern installs. I did this:

Edit the wp-db.php file in the wp-includes directory.
In the function set_prefix($prefix) section

After :

foreach ( $this->tables as $table )
$this->$table = $this->prefix . $table;

Added :
$this->options = ‘wp_’ . ‘options’;

Or whatever your new prefix is. Testing now, I’ll write again if I experience any issues. This is a case of spending 4 hours a few nights ago, and going around in circles. Then after only 20 minutes of trying tonight, getting it working. The benefits of rest apparently.

Here is the rest of the code you would need in addition to the ‘options’ for all of the tables in wordpress.

$this->posts = 'wp_' . 'posts';
$this->categories = 'wp_' . 'categories';
$this->options = 'wp2_' . 'options';
$this->links = 'wp2_' . 'links';
$this->postmeta = 'wp_' . 'postmeta';
$this->terms = 'wp_' . 'terms';
$this->term_taxonomy = 'wp_' . 'term_taxonomy';
$this->term_relationships = 'wp_' . 'term_relationships';

Looks interesting. You original question was sharing a DB across different domains rather than a multiple WP install on one domain and DB. Hope that works for it; post back your results for others to read.

yea that code is for sharing a DB across different domains

it shares everything except the
options links users and usermeta tables