Package: mysql-server-5.7 Version: 5.7.16-2 Severity: serious Hello!
I'm really confused by the change in the postrm introduced in response to LP: #1602945, and I simply do not understand the rationale of the original bug report, and the comment there (and in the git commit log) that "Remove the check on the server binary, since it shouldn't be possible for another package to own that file anyway" is clearly incorrect: during a postrm remove|purge run, if that file exists - which it may well do, it will certainly belong to a different package, such as mysql-server-5.8 or mariadb-server-10.1. Regarding upgrading, I have upgraded from mysql-5.6 to mariadb-10.0 with no noticeable problems whatsoever. I have done a file comparison looking for differences between /var/lib/mysql following this mysql->mariadb conversion and a clean mariadb installation, and the only ones I could see are: mysql/ndb_binlog_index.* mysql/slave_master_info.* mysql/slave_relay_log_info.* mysql/slave_worker_info.* auto.cnf If it is really the case the mariadb needs a different set of files from mysql because of incompatibilities, then they should not share the same /var/lib/mysql or it should be addressed in some other way: mariadb could use /var/lib/mariadb instead, for instance, or the mariadb installation could run some "clean up old /var/lib/mysql directory from mysql instance" (which I think it already does). So by removing the check on the existence of /usr/sbin/mysqld, you leave sysadmins with the potential to inadvertantly wipe their entire running mysql instance's database, for example if they purge an old mysql-server-5.7 after installing mysql-server-5.8 at some point in the future! So as long as the various mysql/mariadb servers share the /var/lib/mysql directory, the check for /usr/sbin/mysqld must be reinstated: I cannot think of any situation in which rm -rf /var/lib/mysql would be desired if /usr/sbin/mysqld is present, as this means that there is some other package with responsibility for /var/lib/mysql installed, and therefore this would fail the Debian policy directive of not interferiyng with other packages' data. (And that is why I have labelled this bug as severity "serious".) If a sysadmin really wants to delete the directory in this situation, they are welcome to do so manually. The patch for this is simple: simply revert commit 554ecf472109f2b2e2fdfa0aaa0302cf2247ac1e This would reopen the LP bug report, and I would ask the original reporter there to explain the circumstances in which there are problems, so that those can be addressed appropriately. In addition, the current postrm_remove_databases debconf question should be enhanced to explicitly mention mariadb. I would also suggest being even more explicit: instead of "the data should be kept", say "do NOT remove the databases, and say NO to this question." Best wishes, Julian
