[wp-trac] [WordPress Trac] #21435: wp-includes/comment.php line85 causes slow query due to the non-indexed column

[WordPress Trac]

#21435: wp-includes/comment.php line85 causes slow query due to the non-indexed
column
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 Reporter:  matsubobo    |       Owner:  pento
     Type:  enhancement  |      Status:  assigned
 Priority:  normal       |   Milestone:  3.9
Component:  Database     |     Version:  3.4.1
 Severity:  minor        |  Resolution:
 Keywords:  has-patch    |     Focuses:  performance
-------------------------+--------------------------

Comment (by matsubobo):

 Replying to [comment:2 pento]:
 > I like this index. I'd also expect it to speed up large import
 processes, which make liberal use of `comment_exists()`.
 >
 > attachment:21435.diff​ updates the patch to apply cleanly against trunk,
 and fixes a couple of typos in the original.


 Thank you for your feedback but It's not a typo.
 The parameter '2' in wcomment_author  is what I expected to avoid deep
 index for string.

   KEY comment_author (wcomment_author(2)),


 Please refer the following MySQL index logic.
 https://dev.mysql.com/doc/refman/5.6/en/create-index.html

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Ticket URL: <https://core.trac.wordpress.org/ticket/21435#comment:7>
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