[wp-trac] [WordPress Trac] #39090: Remove duplicate query from posts page in the admin

[WordPress Trac]

#39090: Remove duplicate query from posts page in the admin
-----------------------------------------+-----------------------------
 Reporter:  rodrigosprimo                |      Owner:
     Type:  enhancement                  |     Status:  new
 Priority:  normal                       |  Milestone:  Awaiting Review
Component:  Posts, Post Types            |    Version:
 Severity:  normal                       |   Keywords:
  Focuses:  administration, performance  |
-----------------------------------------+-----------------------------
 The posts page in the admin (`/wp-admin/edit.php`) is running twice the
 query below. This is a problem specially for sites with a significant
 number of users since this query can be super slow (see #19867 and
 #28160).

 {{{#!php
 SELECT wp_users.ID,wp_users.user_login,wp_users.display_name
 FROM wp_users
 INNER JOIN wp_usermeta
 ON ( wp_users.ID = wp_usermeta.user_id )
 WHERE 1=1
 AND ( ( wp_usermeta.meta_key = 'wp_user_level'
 AND wp_usermeta.meta_value != '0' ) )
 ORDER BY display_name ASC
 }}}


 The query is executed by `WP_User_Query::query()` and, in this particular
 page, is called by the function `wp_dropdown_users()`.

 The attached patch fixes this problem by adding the result to the cache
 when the query is run the first time. Preventing multiple executions of
 the same query.

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Ticket URL: <https://core.trac.wordpress.org/ticket/39090>
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