mariadb/debian/mariadb-server-10.4.README.Debian

* MYSQL WON'T START OR STOP?:
=============================
You may never ever delete the mysql user "root". Although it has no password
is set, the unix_auth plugin ensure that it can only be run locally as the root
user. The credentials in /etc/mysql/debian.cnf specify the user are used by the
init scripts to stop the server and perform logrotation. So in most of the
time you can fix the situation by making sure that the /etc/mysql/debian.cnf
file specifies the root user and no password.

This used to be the debian-sys-maint user which is no longer used.

* WHAT TO DO AFTER UPGRADES:
============================
The privilege tables are automatically updated so all there is left is read
the release notes on https://mariadb.com/kb/en/release-notes/ to see if any
changes affect custom apps.

* WHAT TO DO AFTER INSTALLATION:
================================
The MySQL manual describes certain steps to do at this stage in a separate
chapter.  They are not necessary as the Debian packages does them
automatically.

The only thing that is left over for the admin is
 - setting the passwords
 - creating new users and databases
 - read the rest of this text

* NETWORKING:
=============
For security reasons, the Debian package has enabled networking only on the
loop-back device using "bind-address" in /etc/mysql/my.cnf.  Check with
"netstat -tlnp" where it is listening. If your connection is aborted
immediately check your firewall rules or network routes.

* WHERE IS THE DOCUMENTATION?:
==============================
https://mariadb.com/kb

* PASSWORDS:
============
It is strongly recommended you create an admin users for your database
administration needs.

If your local unix account is the one you want to have local super user
access on your database with you can create the following account that will
only work for the local unix user connecting to the database locally.

  sudo /usr/bin/mysql -e "GRANT ALL ON *.* TO '$USER'@'localhost' IDENTIFIED VIA unix_socket WITH GRANT OPTION"

To create a local machine account username=USERNAME with a password:

  sudo /usr/bin/mysql -e "GRANT ALL ON *.* TO 'USERNAME'@'localhost' IDENTIFIED BY 'password' WITH GRANT OPTION"

To create a USERNAME user with password 'password' admin user that can access
the DB server over the network:

  sudo /usr/bin/mysql -e "GRANT ALL ON *.* TO 'USERNAME'@'%' IDENTIFIED BY 'password' WITH GRANT OPTION"

Scripts should run as a user have the required grants and be identified via unix_socket.

If you are too tired to type the password in every time and unix_socket auth
doesn't suit your needs, you can store it in the file $HOME/.my.cnf. It should
be chmod 0600 (-rw------- username usergroup .my.cnf) to ensure that nobody else
can read it.  Every other configuration parameter can be stored there, too.

For more information in the MariaDB manual in/usr/share/doc/mariadb-doc or
https://mariadb.com/kb/en/configuring-mariadb-with-mycnf/.

ATTENTION: It is necessary, that a ~/.my.cnf from root always contains a "user"
line wherever there is a "password" line, else, the Debian maintenance
scripts, that use /etc/mysql/debian.cnf, will use the username
"root" but the password that is in root's .my.cnf. Also note,
that every change you make in the /root/.my.cnf will affect the mysql cron
script, too.

        # an example of $HOME/.my.cnf
	[client]
	user		= your-mysql-username
	password	= enter-your-good-new-password-here

* FURTHER NOTES ON REPLICATION
===============================
If the MySQL server is acting as a replication slave, you should not
set --tmpdir to point to a directory on a memory-based filesystem or to
a directory that is cleared when the server host restarts. A replication
slave needs some of its temporary files to survive a machine restart so
that it can replicate temporary tables or LOAD DATA INFILE operations. If
files in the temporary file directory are lost when the server restarts,
replication fails.

* DOWNGRADING
============================
Unsupported. Period.

You might get lucky downgrading a few minor versions without issued. Take a
backup first. If you break it you get to keep both pieces. Do a restore from
backup or upgrade to the previous version.

If doing a major version downgrade, take a mysqldump/mydumpber consistent
backup using the current version and reload after downgrading and purging
existing databases.

* BACKUPS
============================
Backups save jobs. Don't get caught without one.