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MySQL Cluster
Presentation by
Krishna
What is MySQL Cluster ?

Just like Hadoop, it is a technology/framework for distributed databases.

ACID compliant.

Horizontal scaling of (MySQL server + storage engine).

In a nut shell it provides clustering for the MySQL DBMS.
MySQL Cluster
Design principles

High write scalability- auto sharding.

99.99 % availability- Shared nothing design.

Real-Time responsiveness- in memory data base system.

Low TCO and Open platform.
MySQL Cluster
Implementation

Implemented through NDB (Network database) storage Engine.

NDB cluster- against shared storage.

Nodes in MySQL Cluster are categorized into three categories namely:
MySQL Cluster
1.
Data Nodes
2.
SQL Nodes
3.
Management Nodes
Architecture
MySQL Cluster
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Data Node

Implemented as a ndb or ndbmtd in the NDB cluster.

Primary function is to process and retrieve information.

Monitoring other nodes in the cluster and notifying the Management
node.

Perform recovery on restart.
MySQL Cluster
SQL Node

Runs as the mysqld program, provides application access to the data
nodes by receiving all interaction requests as queries.

Interaction layer between MySQL clients and the data nodes.

Typically , SQL node is a MySQL server which uses the NDB cluster storage
engine.
MySQL Cluster
Management Node

Manages all other nodes in the Cluster.

Performs functions such as providing configuration details, starting and
stopping the nodes, running back up etc..

Key point - a node of this type should be started first, before any other
node.
MySQL Cluster
Cluster Configuration

Information regarding the number of nodes (processes), hosts , and their
properties is necessary to set up the cluster.

Local configuration file- residing on each data/API node.

Global configuration file- the central one residing on one or more
management nodes.
MySQL Cluster
Configuration files
#
# config.ini
#
[NDB_MGMD DEFAULT]
Portnumber=1186
[NDB_MGMD]
NodeId=49
HostName=10.30.12.23
DataDir=C:/Users/kummadisingu/MySQL_Cluster/49/
Portnumber=1186
[NDBD]
NodeId=1
HostName=10.30.12.28
DataDir=C:/Users/kummadisingu/MySQL_Cluster/1/
[MYSQLD]
NodeId=54
HostName=10.30.12.30
MySQL Cluster
# my.cnf
#
[mysqld]
log-error=mysqld.54.err
datadir="C:/Users/kummadisingu/MySQL_Cluster/54/"
basedir="C:/Program Files/MySQL/MySQL Cluster 7.3/"
port=3307
ndbcluster=on
ndb-nodeid=54
ndb-connectstring=10.30.12.23:1186,
Auto-Sharding

MySQL Cluster automatically partitions the tables across data nodes in the
NDB cluster.

By default, sharding is based on hashing of the primary key, which
generally leads to a more even distribution of data and queries across the
cluster

Automatically creates node groups based on configuration parameters.
MySQL Cluster
How it happens ?
MySQL Cluster
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Continued Operation of MySQL Cluster
MySQL Cluster
F1~ fragment 1 of partition 1
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1.
As long as each node group
participating in the cluster has at least
one node operating, the cluster has a
complete copy of all data and remains
viable.
2.
However, if both nodes from either node
group fail the cluster has lost an entire
partition and so can no longer provide
access to a complete set of all cluster
data
MySQL Cluster Replication

Multiple clusters within a cluster – scenario when Geographical replication
is in demand.

Synchronous replication- happens only between data nodes and uses the
two phase commit protocol.

Asynchronous replication- replication between two or more clusters (multi
master).
MySQL Cluster
CAP theorem and MySQL Cluster

A single MySQL Cluster prioritizes data consistency over availability when
network partitions occur.

A pair of asynchronously replicating MySQL Clusters prioritizes service
availability over data consistency when network partitions occur.
That’s Great!
MySQL Cluster
Single MySQL Cluster - CP

When a network partition occurs, live nodes in each partition regroup and
decide what to do next:

If there are not enough live nodes to serve all of the data stored –
shutdown ~ degrade availability.

After partition if the live nodes still holds all of the data- Continue to
provide service.
MySQL Cluster
Asynchronously replicating clusters - AP

Data consistency within each cluster is guaranteed as normal, but data
consistency across the two clusters is not because of asynchronous
replication.

And yet, continue to accept read and write requests by implementing a
special type of consistency mechanism known as …
Eventually Consistent
MySQL Cluster
?
NoSQL and MySQL Cluster

All the benefits of an ACID RDBMS +
performance capabilities of Key/Value
store = MySQL Cluster

By pass the SQL layer and directly access
the data nodes via the memcache API or
various other NoSQL interfaces.
MySQL Cluster
MySQL Cluster & Memcache API
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MySQL Cluster
1.
key-value interaction with NDB engine via
the familiar memcached API.
2.
Extra caching layer~ very low latency.
Scheme-less storage in MySQL Cluster

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MySQL Cluster
By default, every Key / Value is written to the same table
with each Key / Value pair stored in a single row - thus
allowing schema-less data storage
NoSQL + SQL
Alternatively, we can define a keyprefix so that each value is linked to
a pre-defined column in a specific
table.
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MySQL Cluster
Additional Features

Online scaling & up-gradation without temporary outage.

Elastic in nature ~ compatible with the cloud computing framework.

Unlike other distributed databases, MYSQL Cluster supports execution of
complex join queries- preserving ACID properties.
MySQL Cluster
Resilient to Failures

MySQL Cluster
Employs a self healing auto recovery mechanism with :
1.
Automatic transfer of control.
2.
Automatic restart and resynchronize.
3.
~No Single point failures.
Queries: Two key points to remember

For a table to be replicated in the cluster, it must use the NDB Cluster
storage engine by specifying “ENGINE=NDBCLUSTER”:
CREATE TABLE table_name (col_name column_definitions) ENGINE=NDBCLUSTER;
ALTER TABLE table_name ENGINE=NDBCLUSTER;

MySQL Cluster
Every NDBCluster has a primary key. If no primary key is defined by the
user when a table is created, the NDBCluster storage engine
automatically generates a hidden one.
Limitations

Partitioning.
- Limited partitioning schemes.
- Upper limit on the maximum number of partitions:
~ 8 * [ number of node groups ]

Storage size.
- Single MYSQL cluster has a storage limit of 3TB, which is very low.
MySQL Cluster
Compare
MySQL Cluster
1.
Unrestricted data size
1.
Real time analytics
2.
Batch processing
2.
Mission critical applications
3.
Disk storage
3.
Data Integrity
Conclusion

MySQL’s answer to the NoSQL competitors in
the big data web market.

Certainly brings out the best of the both
worlds.

MySQL Cluster is already serving some of the
most demanding web and mobile services on
the planet
MySQL Cluster
Customers
MySQL Cluster
Available Versions

MySQL Cluster GA (Generally available)

MySQL Cluster Carrier Guide Edition (Community and Commercial
versions)
Includes MySQL Cluster Manager
24 hour online support.
MySQL Cluster
MySQL Cluster