[wp-trac] [WordPress Trac] #41716: Check for utf8mb4 incorrectly assumes auto-truncating indexes

[WordPress Trac]

#41716: Check for utf8mb4 incorrectly assumes auto-truncating indexes
--------------------------+-----------------------
 Reporter:  straussd      |       Owner:  pento
     Type:  defect (bug)  |      Status:  assigned
 Priority:  normal        |   Milestone:  4.9
Component:  Database      |     Version:  4.2
 Severity:  normal        |  Resolution:
 Keywords:  has-patch     |     Focuses:
--------------------------+-----------------------

Comment (by danielbachhuber):

 @pento When running 41716.diff on Pantheon, I see this error in the test
 log:

 {{{
 <div id="error"><p class="wpdberror"><strong>WordPress database
 error:</strong> [Index column size too large. The maximum column size is
 767 bytes.]<br /><code>
                         CREATE TABLE wptests__test_truncated_index (
                                 a varchar(255) COLLATE utf8mb4_unicode_ci,
                                 KEY a_key (a)
                         ) ENGINE=InnoDB
 ROW_FORMAT=COMPACT</code></p></div>
 }}}

 And this test failure:

 {{{
 1) Tests_dbDelta::test_truncated_index
 Failed asserting that Array &0 (
     'wptests__test_truncated_index' => 'Created table
 wptests__test_truncated_index'
 ) is identical to Array &0 ().
 }}}

 I see the same test failure when running the test locally.

 {{{
 $ mysql --version
 mysql  Ver 15.1 Distrib 10.2.8-MariaDB, for osx10.12 (x86_64) using
 readline 5.1
 }}}

 My understanding is that the table **is not** being created when the index
 column size is too large. Subsequently, dbDelta reports the table needs to
 be created when the test expects the table is already created.

--
Ticket URL: <https://core.trac.wordpress.org/ticket/41716#comment:6>
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