[wp-trac] [WordPress Trac] #24093: WP_Meta_Query is inefficient when referencing the same keys in "OR" query

[WordPress Trac]

#24093: WP_Meta_Query is inefficient when referencing the same keys in "OR" query
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 Reporter:  sc0ttkclark                          |       Owner:
     Type:  enhancement                          |      Status:  new
 Priority:  normal                               |   Milestone:  4.0
Component:  Query                                |     Version:  3.5.1
 Severity:  normal                               |  Resolution:
 Keywords:  needs-refresh meta-query needs-      |     Focuses:
  unit-tests has-patch                           |  performance
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Comment (by ve9gra):

 This "bug" reared its ugly head after using a plugin by vprat. Using mySQL
 profiling I found the impact to be crippling after adding more than a few
 groups to a user. And keep in mind that this install is very small... like
 around 15 posts. I'm sure a site with more posts would get impacted much
 earlier as adding multiple INNER JOIN statements blow up the tempDB
 exponentially.

 You can see the thread with my investigation here - http://customer-
 area.marvinlabs.com/support/topic/user-in-multiple-groups-causes-page-
 hang-and-100-cpu/

 I would really like to have this merged into core as soon as possible.
 I've tested the patch on 3.9.1 with no issues - or at least none that I
 could find.

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Ticket URL: <https://core.trac.wordpress.org/ticket/24093#comment:19>
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