[wp-trac] [WordPress Trac] #60159: Performance Issues with Large Number of Categories in WordPress Admin Panel

[WordPress Trac]

#60159: Performance Issues with Large Number of Categories in WordPress Admin Panel
---------------------------+-----------------------------
 Reporter:  rangedpenguin  |      Owner:  (none)
     Type:  enhancement    |     Status:  new
 Priority:  normal         |  Milestone:  Awaiting Review
Component:  General        |    Version:  6.4.2
 Severity:  minor          |   Keywords:
  Focuses:                 |
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 I am currently using WordPress version 6.4.2 on an Apache2 server with
 Ubuntu. My site has a large number of taxonomies, specifically over
 200,000 categories. I've noticed significant performance issues in the
 WordPress admin panel, particularly when interacting with categories
 (adding, deleting, or loading in /wp-admin/edit.php).

 Through observation and testing, it seems that the issue is specifically
 related to categories and their association with posts. When all
 categories are removed, but a similar number of tags is present, the
 performance of WordPress improves dramatically, leading me to believe that
 the problem lies in the way categories are handled, particularly in their
 association with posts.

 Here's an example of the SQL query that seems to be causing performance
 issues while in admin panel:

 {{{
 SELECT t.*, tt.*
 FROM notwplol_terms AS t
 INNER JOIN notwplol_term_taxonomy AS tt
 ON t.term_id = tt.term_id
 WHERE t.term_id IN (475407,201837,531747,396102,14876,609708, ...,
 211701,211702,211703,211704)
 _prime_term_caches
 }}}
 (Note: The list of term IDs in the query is significantly truncated for
 brevity.)

 Steps to Reproduce:
 Have a WordPress instance with over 200k categories & 200k posts.
 Attempt to add or delete categories, or navigate to /wp-admin/edit.php.
 Observe the high server resource usage and slow performance.


 Expected Result:
 The admin panel should handle a large number of categories efficiently
 without significant performance degradation, especially when adding or
 deleting categories or navigating the admin pages.


 Actual Result:
 High server resource usage and slow performance are observed when managing
 categories, indicating a potential issue with how categories and their
 post associations are handled.


 Additional Information:
 This issue is critical for the management of my site, as it significantly
 impacts the ability to efficiently manage categories. Insights into
 optimizing WordPress for handling a large number of categories, or any
 updates that could mitigate this issue, would be highly appreciated.

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Ticket URL: <https://core.trac.wordpress.org/ticket/60159>
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