[wp-trac] [WordPress Trac] #33885: meta_form performs a potentially expensive query

[WordPress Trac]

#33885: meta_form performs a potentially expensive query
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 Reporter:  jorbin                   |       Owner:
     Type:  defect (bug)             |      Status:  new
 Priority:  normal                   |   Milestone:  4.4
Component:  Administration           |     Version:  4.3.1
 Severity:  critical                 |  Resolution:
 Keywords:  has-patch needs-testing  |     Focuses:  performance
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Changes (by pento):

 * keywords:   => has-patch needs-testing
 * milestone:  Awaiting Review => 4.4


Comment:

 I've been playing around a bit with tweaking the query, with not much
 luck. The MySQL optimizer just seems to have some issues with this
 particular prefix index in `utf8mb4`.

 I'm wondering if it would be faster to do the sorting in PHP, instead.
 [attachment:33885.diff] is first pass at that, grabbing a small chunk of
 rows, filtering them, then going back for more as needed.

 For those of you with large data sets you can test on, could you please
 apply this patch, and tell me:

 * What does performance look like to you?
 * Does it give the same results as the current query?

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Ticket URL: <https://core.trac.wordpress.org/ticket/33885#comment:8>
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