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Generic MySQL/MariaDB backend

  • Native: Yes
  • Primary: Yes
  • Secondary: Yes
  • Producer: Yes
  • Consumer: Yes
  • Autosecondary: Yes
  • DNS Update: Yes
  • DNSSEC: Yes (set gmysql-dnssec)
  • Disabled data: Yes
  • Comments: Yes
  • Search: Yes
  • Views: No
  • API: Read-Write
  • :ref:`Multiple instances <setting-launch>`: Yes
  • Zone caching: Yes
  • Module name: gmysql
  • Launch name: gmysql

Warning

If using MySQL with 'slave' support enabled in PowerDNS you must run MySQL with a table engine that supports transactions. In practice, great results are achieved with the 'InnoDB' tables. PowerDNS will silently function with non-transaction aware MySQLs but at one point this is going to harm your database, for example when an incoming zone transfer fails.

Warning

While it is possible to run the Generic MySQL/MariaDB backend on top of MySQL/MariaDB views, we have received several reports of this causing performance problems and memory leaks. Please know that when reporting problems when running PowerDNS on top of a modified schema, our open source support offering requires you to reproduce your problem on an unmodified schema without views.

The default schema is included at the bottom of this page. :ref:`migration-zone2sql` with the --gmysql flag also assumes this layout is in place. For full migration notes, please see :doc:`../migration`. This schema contains all elements needed for master, slave and superslave operation.

When using the InnoDB storage engine, we suggest adding foreign key constraints to the tables in order to automate deletion of records, key material, and other information upon deletion of a domain from the domains table. The following SQL does the job:

.. literalinclude:: ../../modules/gmysqlbackend/enable-foreign-keys.mysql.sql
   :language: SQL

Warning

Please note, however, that setting up these foreign key constraints prevents the PowerDNS database from being usable with mysql group replication, if you are using multiple servers.

Using MySQL/MariaDB replication

To support NATIVE domains, the binlog_format for the MySQL/MariaDB replication must be set to MIXED or ROW to prevent differences in data between replicated servers. See "Setting The Binary Log Format" and "Binary Log Formats" for more information.

Otherwise, you will probably see:

Cannot execute statement: impossible to write to binary log since BINLOG_FORMAT = STATEMENT and at least one table uses a storage engine limited to row-based logging.
InnoDB is limited to row-logging when transaction isolation level is READ COMMITTED or READ UNCOMMITTED.

Settings

gmysql-host

Host (ip address) to connect to. Mutually exclusive with :ref:`setting-gmysql-socket`.

Warning

When specified as a hostname, a chicken/egg situation might arise where the database is needed to resolve the IP address of the database. It is best to supply an IP address of the database here.

gmysql-port

The port to connect to on :ref:`setting-gmysql-host`. Default: 3306.

gmysql-socket

Connect to the UNIX socket at this path. Mutually exclusive with :ref:`setting-gmysql-host`.

gmysql-dbname

Name of the database to connect to. Default: "powerdns".

gmysql-user

User to connect as. Default: "powerdns".

gmysql-group

Group to connect as. Default: "client".

gmysql-password

The password for :ref:`setting-gmysql-user`.

gmysql-dnssec

Enable DNSSEC processing for this backend. Default: no.

gmysql-innodb-read-committed

Use the InnoDB READ-COMMITTED transaction isolation level. Default: yes.

gmysql-ssl

.. deprecated:: 5.0.0

Before 5.0.0: Send the CLIENT_SSL capability flag to the server. SSL support is announced by the server via CLIENT_SSL and is enabled if the client returns the same capability. Default: no.

5.0.0 and up: this option does nothing. Use gmysql-group and put your TLS settings in my.cnf.

gmysql-timeout

The timeout in seconds for each attempt to read from, or write to the server. A value of 0 will disable the timeout. Default: 10

gmysql-thread-cleanup

Older versions (such as those shipped on RHEL 7) of the MySQL/MariaDB client libraries leak memory unless applications explicitly report the end of each thread to the library. Enabling gmysql-thread-cleanup tells PowerDNS to call mysql_thread_end() whenever a thread ends.

Only enable this if you are certain you need to. For more discussion, see #6231.

Default Schema

This is the 4.7 schema.

.. literalinclude:: ../../modules/gmysqlbackend/schema.mysql.sql