[wp-trac] [WordPress Trac] #30814: Large wp_postmeta table causes core database queries to become extremely slow.

[WordPress Trac]

#30814: Large wp_postmeta table causes core database queries to become extremely
slow.
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 Reporter:  turkeybucket  |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Database      |    Version:  4.1
 Severity:  normal        |   Keywords:
  Focuses:                |
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 On a site that I just updated to WordPress 4.1, I found that I was getting
 504 gateway time-out errors at least half the time I tried to load the
 site. The site would load intermittently and was generally much slower
 than it had been before the upgrade. On the server (Nginx PHP 5.4 MySQL
 5.5.40), the MySQL Process Log showed that a lot of the queries for this
 site were hanging up and taking 30 to 60 seconds to complete.

 After digging through the site's database to see what could be causing the
 slow queries I found that an old plugin had left 250,000 rows of data in
 the wp_postmeta table.  I deleted those rows out of the postmeta table
 which left about 20,000 rows -- after deleting those rows, the site
 started loading quickly again and I no longer was getting time out errors.

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Ticket URL: <https://core.trac.wordpress.org/ticket/30814>
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