mysql-server 5.7.12 wrong variables in mysqld.cnf

[billynoah]

The default configuration file for MySQL has a few wrongly named variables, i.e. system variables whose name has changed over versions.

In the file /etc/mysql/mysql.conf.d/mysqld.cnf there are the following lines:

#table_cache = 64
#log_slow_queries = /var/log/mysql/mysql-slow.log
#log-queries-not-using-indexes

The current version of MySQL in use requires these to be named:

table_open_cache
slow_query_log_file
log_queries_not_using_indexes

Although they are commented out, the variables names should be revised to work with the version they accompany. Uncommenting them and/or changing their values will result in mysqld crashing.

[Robie Basak (racb)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. Lars has fixed some of these in https://anonscm.debian.org/cgit/pkg-mysql/mysql-5.7.git/commit/?id=3729592ed5d1e428ba8a215829e2d18c7f669822 (bug 1577096) but I think log_queries_not_using_indexes is left. We should change hyphens to underscores while we are changing the others since we have to do a conffile change at least once to fix the others, so might as well take the opportunity to make things consistent.

[Bert Lindner (bert-lindner-launchpad-net)]

Please note, the structure of logging options has changed. So

# pre 5.7: log_slow_queries points to log file
log_slow_queries = /var/log/mysql/mysql-slow.log

needs to be replaced with two lines:

# >= 5.7: slow_query_log_file points to log file, slow_query_log is a boolean.
slow_query_log = 1
slow_query_log_file = /var/log/mysql/mysql-slow.log