MySQL Bugs: #88227: Connector/J 5.1.44 cannot be used against MySQL 5.7.20 without warnings

Bug #88227	Connector/J 5.1.44 cannot be used against MySQL 5.7.20 without warnings
Submitted:	25 Oct 2017 17:22	Modified:	17 Feb 2018 2:50
Reporter:	Francisco Lozano	Email Updates:
Status:	Closed	Impact on me:	None
Category:	Connector / J	Severity:	S2 (Serious)
Version:		OS:	Any
Assigned to:	Filipe Silva	CPU Architecture:	Any

Description:
MySQL 5.7.20 issues warnings when using `tx_isolation` / `tx_read_only` variables, as they're deprecated and removed from 8.0.3 [1].

However, Connector/J 5.1.44 still uses these variables when connecting to 5.7.20, even if in its release notes it acknowledges that these are deprecated and to be removed [2].

My assumption is that the connector checks the MySQL version and uses the old ones in any 5.7.x and the new ones in 8.0.x (transaction_isolation, transaction_read_only). 

Many systems will deal with SQL-level warnings as errors, and raise exceptions when these are found. MySQL 5.7.20 is unusable in any system like that without a fixed Connector/J.

By the way, it's pretty bad to refer from release notes to bug numbers that can't be seen in bugs.mysql.com, please see [3]. It's annoying and shows little respect for open-source users.

[1] https://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-20.html
[2] https://dev.mysql.com/doc/relnotes/connector-j/5.1/en/news-5-1-44.html
[3] https://bugs.mysql.com/bug.php?id=26440544

How to repeat:
Just use Connector/J 5.1.44 with MySQL 5.7.20 and try to perform transactions.

Suggested fix:
Connector/J should stop using tx_isolation and tx_read_only for any MySQL 5.7.x where x >=20.

Hello Francisco,

Thank you for the bug report.
Verified based on internal discussion with dev's.

Thanks,
Chiranjeevi.

Given that this is confirmed and that this renders latest MySQL unusable from Java... when do you plan to fix?

Posted by developer:
 
Added the following entry to the Connector/J 5.1.46 changelog:

"When Connector/J 5.1.44 or earlier connected to MySQL 5.7.20 or later, warnings are issued because Connector/J used the deprecated system variables tx_isolation and tx_read_only. These SQL-level warnings, returned from a SHOW WARNINGS statement, might cause some applications to throw errors and stop working. With this fix, the deprecated variables are no longer used with MySQL 5.7.20 and later; also, to avoid similar issues, a SHOW WARNINGS statement is no longer issued for the use of deprecated variables."