Take the tour ×  I'm researching the structure of WordPress
database and there is something that really get me confuesd.
Could someone please explain, what is the exact job of meta_key
and meta_value fields in wp_commentmeta, wp_postmeta,
wp_usermeta tables? What is the job of these tables anyway?  I
did read the Database Description in the Codex, but still don't
get it.  share|improve this question add comment  1 Answer  up
vote 1 down vote accepted  Think of them as array key/value
pairs (kinda). These tables are used to store additional data
about particular posts, comments, or users. The meta_key is the
name by which the meta_value is retrieved, plus you have
associations with particular posts, comments, or users by means
of IDs. As far as structure goes, that is about it. These are
"extra info" tables. You can even add to them via the backend.
*_postmeta is where the custom fields are stored.  WordPress
stores, and plugins and themes can store, a wide variety or
information there. Some of those tables ha