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What is MariaDB Galera?
MariaDB Galera Cluster is a virtually synchronous multi-primary cluster for MariaDB. It is available on Linux only, and only supports the InnoDB storage engine (although there is experimental support for MyISAM and, from MariaDB 10.6, Aria.
How does Galera Cluster work?
Galera Cluster is a synchronous multi-master replication plug-in for InnoDB. An application can write to any node in a Galera cluster, and transaction commits (row-based replication events) are then applied on all servers, via a certification-based replication.
How do I know if Galera is running?
I know to check the Galera cluster status, the command that should be used after login to the mysql client is: SHOW STATUS LIKE ‘wsrep%’;
How does Galera Cluster store write-sets in memory?
Galera Cluster uses an allocation algorithm that attempts to store write-sets in the above order. That is, first it attempts to use permanent in-memory store. If there is not enough space for the write-set, it attempts to store to the permanent ring-buffer file.
Do you need more memory for MariaDB Galera?
During normal operation a MariaDB Galera node does not consume much more memory than a regular MariaDB server. Additional memory is consumed for the certification index and uncommitted writesets, but normally this should not be noticeable in a typical application. There is one exception though:
How are state transfers done in Galera Cluster?
The process of replicating data from the cluster to the individual node, bringing the node into sync with the cluster, is known as provisioning. There are two methods available in Galera Cluster to provision nodes: State Snapshot Transfers (SST) Where a snapshot of the entire node state transfers.
How to get started with MariaDB Galera Cluster?
In MariaDB 10.1 and later, the MySQL-wsrep patch has been merged into MariaDB Server. This means that the functionality of MariaDB Galera Cluster can be obtained by installing the standard MariaDB Server packages and the Galera wsrep provider library package.
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