Codership is there to secure our customers’ invaluable data. We do this by providing high availability, no-data-loss and

scalable data replication and clustering solutions for open source databases.

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What is the Meaning of Galera ?

Turns out it has different semantics in:● Italy● Uruguay● Brazil● Spain, Portugal, Russia...

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Galera in Italy

Che cosa significa la parola galera?

Jail / Prison

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Galera in Uruguay

Que significaca galera en Uruguai?

Traditional tall hat

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Galera in Brazil

A Group of Happy People

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Galera in Spain, Portugal, Russia...

Galley

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Asynchronous Replication

Can be a mess....

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Synchronous Replication

That's more like it !!

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MariaDB

Synchronous Multi-Master Replication

Galera Replication

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MariaDB MariaDB

Synchronous Multi-Master Replication

Galera Replication

There can be several nodes

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MariaDB MariaDB MariaDB

Synchronous Multi-Master Replication

Galera Replication

There can be several nodes

Nodes can be added on the fly

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MySQL MySQL MySQL

Synchronous Multi-Master Replication

Galera Replication

Client can connect to any node

There can be several nodes

Nodes can be added on the fly

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MariaDB MariaDB MariaDB

Synchronous Multi-Master Replication

Galera Replication

Client can connect to any node

There can be several nodes

read & write read & write read & write Read & write access to any node

Nodes can be added on the fly

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MariaDB MariaDB MariaDB

Synchronous Multi-Master replication

Galera ReplicationReplication is synchronous

read & write read & write read & write

Client can connect to any node

Each node have identical data

Read & write access to any node

Add nodes on the fly

There can be several nodes

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MariaDB

Multi-Master Replication

Multi-master cluster looks like one big database with multiple entry points

read & write read & write read & write

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MariaDB MariaDB MariaDB

Synchronous Replication

aGalera Replication

Read & write

Transaction is processed locally up to commit time

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MariaDB MariaDB MariaDB

Synchronous Replication

Galera Replication

commit

Transaction's write set is replicated to whole cluster

Slave queueSlave queue

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Galera Replication

MariaDB MariaDB MariaDB

Synchronous Replication

OK

Client gets OK status

Slave queueSlave queue

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Galera Replication

MariaDB MariaDB MariaDB

Synchronous Replication

Transaction is applied in slaves

Slave queueSlave queue

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MariaDB MariaDB MariaDB

How node failures are handled

a

Galera Replication

Load Balancing

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MariaDB MariaDB MariaDB

Quorum, handling the failure

a

Galera Replication

Load Balancing

● Galera uses quorum based failure handling:

– When cluster partitioning is detected, the majority partition "has quorum" and can continue

– A minority partition cannot commit transactions, but will attempt to re-connect to primary partition

– Note: 50% is not majority!=> Minimum 3 nodes recommended.

● Load balancer will notice errors & remove node from pool

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Galera ReplicationA

Optimistic Concurrency Control

commit

Trx A

B

commit

Trx B

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Optimistic Concurrency Control

●Transactions process independently in each cluster node

●Transaction write sets will be replicated at commit time (before commit)

●Cluster wide conflicts will be resolved and conflict victim must rollback

Optimistic Concurrency Control

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MariaDB

Parallel Replication

Slave queue

Slave thd Slave thd

Slave control

Any number of slave applier threads can be started

Slave control assigns write sets for slave appliers

Slave control is on ROW level

Only applying is parallel, commit order is dictated

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Galera Cluster benefits

➢ Synchronous multi-master cluster➢ no data loss➢ no slave lag➢ No complex slave failover

➢ For MySQL/MariaDB InnoDB➢ No single point of failure

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Galera Cluster benefits

➢ Good Performance and scalability➢ Optimistic concurrency control➢ Parallel Replication➢ Optimized Group Communication

➢ 99.99% transparent➢ InnoDB look & feel

➢ Automatic node joining➢ Works in LAN / WAN / Cloud

28www.codership.com

Codership Company

● Established 2007 ● Three MySQL Clusters before Galera

Cluster● Open source + support sales● Active community, hundreds of users● Latest release 3.1 Galera Cluster● MariaDB Galera Cluster 5.5.33

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Who is using Galera?

Mercadolibre OpenStack Galera deployment

If you live in Latin America (and even if you don't) you most likely know the online trading platform

MercadoLibre. MercadoLibre is where 58 million consumers in Argentina, Brazil, Chile, Colombia,

Ecuador, Mexico, Peru, Uruguay, and Venezuela go to buy and sell. Among the world's e-commerce market

leaders, MercadoLibre was recognized in 2010 as one of the top 30 world's hottest brands.

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Galera Project

MySQL

MariaDBmerge

merge

MySQL Community Edition

MariaDBGalera Cluster for MySQL

MariaDB FeaturesAPI

MySQL

Galera Replication plugin

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Galera Project

API

Galera Replication plugin

API

MariaDB

MySQL Community Edition

MariaDB Galera Cluster

MySQL

Galera Cluster for MySQL

merge

Galera Replication plugin

MySQL

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Galera Support

CodershipLevel 3 support, Galera

MontyProgramLevel 3 Support, MariaDB

GaleraCluster

MariaDBGaleraCluster

SkySQLSupport Subscriptions

More info www.codersip.com

Sakari.keskitalo@codership.comSkySQL.comMariadb.org