killall -9 in init-script

[Erkan Yanar]

From /etc/init.d/mysql
#v+
  'stop')
        # * As a passwordless mysqladmin (e.g. via ~/.my.cnf) must be possible
        # at least for cron, we can rely on it here, too. (although we have
        # to specify it explicit as e.g. sudo environments points to the normal
        # users home and not /root)
        log_daemon_msg "Stopping MariaDB database server" "mysqld"
        if ! mysqld_status check_dead nowarn; then
          set +e
          shutdown_out=`$MYADMIN shutdown 2>&1`; r=$?
          set -e
          if [ "$r" -ne 0 ]; then
            log_end_msg 1
            [ "$VERBOSE" != "no" ] && log_failure_msg "Error: $shutdown_out"
            log_daemon_msg "Killing MariaDB database server by signal" "mysqld"
            killall -15 mysqld
            server_down=
            for i in 1 2 3 4 5 6 7 8 9 10; do
              sleep 1
              if mysqld_status check_dead nowarn; then server_down=1; break; fi
            done
          if test -z "$server_down"; then killall -9 mysqld; fi
          fi
        fi
#v-

First I see no reason to use anything else than killall -15.
But:
Imagine the connections of the server are exhausted. Then after the killall -15 the server has 10 seconds to stop. After that a SIGKILL is gonna send.
Now if the shutdown is going to take some time especially for bigger databases with i.e. delay_key_write. The database is going to be corrupted afterwards.
Anyway a recovery is being forced.
So this is going to hurt bigger installations more likely.
It is also likely mysqladmin is going to fail, because you installed a dump from another server (then /etc/mysql/debian.cnf will not match the credentials in the server anymore)