Although the data for all the user likes is stored in a custom table, the count of likes for each post is stored in post meta with the key ‘wpum_likes’. This makes it easy to query and sort posts using the
WP_Query function.
For example, you can get all posts ordered by those with the most likes with this code:
https://gist.github.com/wp-user-manager/cc6f354876b1a7716e22ef393592d119
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