Database Integrations

We generally recommend using PostgreSQL for a database. If high availability is not a consideration we also support SQLite3.

It is also a general recommendation that if you’re using PostgreSQL, MySQL, or MariaDB; that you do not automatically upgrade the major/minor version of these databases, and pin the image tag so at most the patch version is updated. For example for database version x.y.z only the z should change, x and y should remain the same.

It is also generally recommended that you do not rely on automatic update tools to perform this action unless you are sure they shut down the container properly (i.e. with a graceful stop).

While this guide exists and it contains some guidance on managing the database being used, it is by no means exhaustive or intended as such and users should refer to the database vendors documentation.

PostgreSQL#

The only current support criteria for PostgreSQL at present is that the version you’re using is supported by the PostgreSQL developers. See Vendor Supported Versions more information.

We generally perform integration testing against the latest supported version of PostgreSQL and that is generally the recommended version for new installations.

Vendor Supported Versions#

See the PostgreSQL Versioning Policy for information on the versions and platforms that are currently supported by this vendor.

MySQL#

MySQL and MariaDB are both supported as part of the MySQL implementation. This is generally discouraged as PostgreSQL is widely considered as a significantly better database engine. If you choose to go with MySQL, we recommend specifically using the MariaDB backend.

MySQL comes with some rigid support requirements in addition to the standard requirements for us supporting a third party.

1. Must both support the InnoDB engine and this engine must be the default engine.
2. Must support the utf8mb4 charset.
3. Must support the utf8mb4_unicode_520_ci collation.
4. Must support maximum index size of no less than 2048 bytes. The default maximum index size for the InnoDB engine is 3072 bytes on:
   1. MySQL 8.0 or later.
   2. MySQL 5.7 or later provided:
      1. The innodb_large_prefix option is ON.
   3. MariaDB 10.3 or later.
5. Must support ANSI standard time behaviors. See ANSI standard time behaviors.

We generally perform integration testing against the latest supported version of MySQL and MariaDB, and the latest supported version of MariaDB is generally the recommended version for new installations.

Specific Notes#

InnoDB Large Prefixes#

This can be configured in the MySQL configuration file by setting the innodb_large_prefix option to on. According to the Oracle documentation this is the default behavior in MySQL 5.7 and it can’t be turned off in MySQL 8.0 or in MariaDB 10.3 and later.

[mysqld]
innodb_large_prefix = ON

ANSI standard time behaviors#

This can be configured in the MySQL configuration file by setting the explicit_defaults_for_timestamp value to on. According to the Oracle documentation this is the default behavior in MySQL 5.7 and MySQL 8.0. This is however not the default behavior in MariaDB before 10.10.

[mysqld]
explicit_defaults_for_timestamp = ON

Upgrades#

MySQL and MariaDB have several standard but important system databases named mysql, sys, and performance_schema. These databases are outside the scope and not intended for individual applications to manage as they are system databases used by MySQL and MariaDB internally.

These servers/engines may successfully start when these databases are incompatible with your particular MySQL or MariaDB version, but may raise errors when you attempt to use particular features of the database. This may lead a user to believe the server/engine is functioning correctly when it is in fact running with a potentially badly corrupted schema.

The risk here is that the database may run for an extended period of time unnoticed and may be getting more and more corrupt with no visible signs until it’s no longer recoverable. This makes it critically important users do not neglect this operation or ensure it’s happening.

While some MySQL or MariaDB containers will do this automatically or give users an option to perform this automatically, it is strongly recommended that this process is manually done and only done after doing a backup of all databases on the server as is the recommendation from both MySQL and MariaDB.

It is your responsibility to ensure these tables are upgraded as per the mysql_upgrade and mariadb_upgrade documentation.

Vendor Supported Versions#

MariaDB Vendor Supported Versions#

See the MariaDB Server Releases for information on the versions and platforms that are currently supported by this vendor.

MySQL Vendor Supported Versions#

See the MySQL Supported Platforms for information on the versions and platforms that are currently supported by this vendor.