[wp-trac] [WordPress Trac] #37689: Issues with utf8mb4 collation and the 4.6 update

[WordPress Trac]

#37689: Issues with utf8mb4 collation and the 4.6 update
--------------------------+--------------------------
 Reporter:  Hristo Sg     |       Owner:  pento
     Type:  defect (bug)  |      Status:  closed
 Priority:  normal        |   Milestone:  4.6.1
Component:  Database      |     Version:  4.6
 Severity:  normal        |  Resolution:  fixed
 Keywords:  has-patch     |     Focuses:  performance
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Changes (by pento):

 * owner:   => pento
 * status:  new => closed
 * resolution:   => fixed


Comment:

 In [changeset:"38441"]:
 {{{
 #!CommitTicketReference repository="" revision="38441"
 Database: Don't force an unsupported character set that previously
 would've silently failed.

 [37320] corrected some behaviour in how PHP and MySQL character sets are
 matched up. This was correct, but had the side effect of causing some
 incorrectly configured sites to start failing.

 Prior to [37320], if `DB_CHARSET` was set to `utf8mb4`, but the PHP
 version didn't support `utf8mb4`, it would fall back to the default
 character set - usually `latin1`. After [37320], the `SET NAMES` query
 would force MySQL to treat the connection character set as `utf8mb4`, even
 if PHP wasn't able to understand it.

 By checking if `mysqli_set_charset()` succeeded, we can simulate the old
 behaviour, while maintaining the fix in [37320].

 Props danielkanchev fo helping to diagnose this issue.
 Fixes #37689 for trunk.
 }}}

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Ticket URL: <https://core.trac.wordpress.org/ticket/37689#comment:20>
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