Bug #93450 mysqldump does not wrap SET NAMES into mysql-extension comment

• Submitted: 3 Dec 2018 13:20
• Modified: 9 Apr 16:39
• Reporter: Mattias Jonsson (OCA)
• Status: Closed
• Category: MySQL Server: mysqldump Command-line Client
• Severity: S3 (Non-critical)
• Version: 8.0, 8.0.13
• OS: Any
• CPU Architecture: Any

[3 Dec 2018 13:20] Mattias Jonsson

Description:
In WL#10353 there was a change in the output of mysqldump, no longer wrapping SET NAMES in an mysql-extension comment, breaking its compatibility with other imports (like vitess).

Commit with changes (including result files) that:
https://github.com/mysql/mysql-server/commit/ebaff9fffc958030a57d8ea7f1f2d527cac1df64

I cannot see any reason or comments on why the the wrapping was removed.

How to repeat:
See: https://github.com/mysql/mysql-server/commit/ebaff9fffc958030a57d8ea7f1f2d527cac1df64#diff...

Where it is clear that:
/*!40101 SET character_set_client = utf8 */;
was changed to:
 SET character_set_client = utf8mb4 ;
without any mysql-extension comment protecting it from being parsed by a non mysql-extension aware parser.

Suggested fix:
Wrap the 'SET NAMES = <character_set>' command in mysqldump like:
/*50503 SET NAMES = utf8mb4 */;

So non mysql-extension aware parsers can still parse the dump.
I assume utf8mb4 was added by 5.5.3:
https://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-3.html

[4 Dec 2018 4:00] Umesh Shastry

Hello Mattias,

Thank you for the report and feedback!

regards,
Umesh

[9 Apr 16:39] Paul Dubois

Posted by developer:
 
Fixed in 8.0.17.

mysqldump failed to wrap SET NAMES utf8mb4 and SET
character_set_client = utf8mb4 statements within version-specific
comments, which could cause compatibility problems.