MariaDB Galera server logs all the cluster related information like node status, cluster status, membership, etc. in the error log. MariaDB 10.1.2 introduces a new INFORMATION SCHEMA plugin WSREP_INFO that enables querying these information via INFORMATION SCHEMA tables. The WSREP_INFO plugin adds two new tables to the Information Schema, WSREP_MEMBERSHIP and WSREP_STATUS. The plugin is not enabled by default, so in order to use it, it needs to be installed first :

Now that WSREP_INFO plugin is installed, lets look into the contents of these tables on a 3-node cluster.

As seen above, WSREP_MEMBERSHIP table shows information about current members in the cluster which includes node’s name and incoming address. WSREP_STATUS table, on the other hand, shows status information about the node and cluster as a whole.

SHOW command can also be used to query these tables. Its quick and reduces the number of columns for WSREP_STATUS to fit to the screen.

Download MariaDB Galera Cluster 10.0.15

Release Notes Changelog What is MariaDB Galera Cluster?

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mariadb-seal-shaded-browntext-altThe MariaDB project is pleased to announce the immediate availability of MariaDB Galera Cluster 10.0.15. This is a Stable (GA) release.

See the Release Notes and Changelog for detailed information on this release and the What is MariaDB Galera Cluster? page in the MariaDB Knowledge Base for general information about the MariaDB Galera Cluster series.

Thanks, and enjoy MariaDB!

MariaDB 10.1 server is now “Galera ready” with the latest 10.1.1 release. It includes wsrep (write set replication) patch that enables server to load the wsrep provider (galera) library and interact with it to provide multi-master synchronous replication support. The patch implements hooks inside server and storage engines to populate and apply the write sets on sender and receiver nodes in a cluster respectively. The wsrep patch also adds a number of system and status variables (prefixed with wsrep) that can be used to configure and monitor the server acting as a node in Galera cluster.

Unlike older MariaDB versions, the wsrep patch is now part of regular (vanilla) MariaDB 10.1 server, that is, with 10.1.1 there would be no separate vanilla and Galera server versions. As a result, same 10.1 packages (binary tarballs, deb, rpm, etc.) can now be used to run MariaDB server as standalone server or a node in MariaDB Galera cluster.

As a standalone server, it would require no additional settings, just your usual favorite options. However, if one wants to start it as a MariaDB Galera node the following mandatory settings would be required :

  • wsrep_on=ON
  • wsrep_provider
  • wsrep_cluster_address
  • binlog_format=ROW
  • default_storage_engine=InnoDB
  • innodb_autoinc_lock_mode=2
  • innodb_doublewrite=1
  • query_cache_size=0

Without these additional settings the Galera replication essentially gets disabled and server functions like a standalone server with no Galera-related overhead.

If you are building MariaDB 10.1 server from source, WITH_WSREP cmake switch (ON by default) can be used to control the inclusion of wsrep patch in the build.

More about MariaDB Galera cluster: