Coming to Cassandra from Relational World

April 2016

Nenad Bozic@NenadBozicNsnenad.bozic@smartcat.io

SmartCatwww.smartcat.io

@SmartCat_io

Relational Databases

• easy to start with, need only SQL

• can be used without knowledge of internals

• we choose the vendor which we know best

• limitless indexes and query patterns

We Live in Data Intensive Environment

• Everything is connected to internet, expansion of IoT, social networks

• 90% of stored data is gathered in the last 2 years

• Enterprise is moving to BASE

Agenda

• NoSQL space

• Cassandra architecture

• How (not) to start with Cassandra

• Cassandra learning path

NoSQL Space

NoSQL

• they are not hype anymore

• not general purpose storage, built to solve specific use case

• built with performance and scalability in mind

• each type, even more, each vendor is different

http://bigdata-blog.com/key-value-database

Polyglot Persistence

http://martinfowler.com/bliki/PolyglotPersistence.html

Cassandra

Cassandra Overview

• Data is available, partitioned with tunable consistency

• Both data and load is distributed

• Replication factor - how many replicas

• Masterless architecture

• Fast, scalable and fault tolerant

• Native multi-datacenter support

Architecture

Client contact

Architecture

Client request

Consistency level 1Replication factor 3

Architecture

Client request

response

Consistency level 1Replication factor 3

Architecture

DC1 DC2

Cluster

Single - Row Partitions

http://www.slideshare.net/planetcassandra/datastax-rigorous-cassandra-data-modeling-for-the-relational-data-architect

Multi - Row Partitions

http://www.slideshare.net/planetcassandra/datastax-rigorous-cassandra-data-modeling-for-the-relational-data-architect

Data Modeling

• query based modeling

• data is denormalized

• data is duplicated

Use Cases

• when high availability is crucial, and eventual consistency is tolerable

• event sourcing

• logging continuous streams of data

• deep visitor analytics

• early prototyping with significant query changes

• referential integrity required

• dynamic access patterns on data

Cassandra in Data Science

• native support for multi DC (main and analytics DC)

• Cassandra Spark connector with data locality

• Cassandra is suitable for web analytics

• SMACK stack - real time analytics

Our Two Cents on Cassandra

Red Flags - how not to start with Cassandra

• do not use Cassandra on single node

• watch out for write - read antipattern

• watch out for read - write antipattern

• change the way you model data, avoid relational data modeling

• do not be afraid of evolving data model

Learning path

• watch Martin Fowler Introduction to NoSQL video

• read history (DynamoDB and BigTable)

• finish up DS201: Cassandra Core Concepts course

• finish up DS220: Data Modeling course

• bonus: listen to Patrick McFaddin on topic of data modeling

Links

• SmartCat Blog post - How (not) to start with Cassandra

• SmartCat Blog post - Polyglot persistence in NoSQL space

• Kristof Kovacs - NoSQL database blog post

• Martin Fowler - Introduction to NoSQL

• DS201 - Cassandra Core Concepts

• DS220 - Data Modeling

Q&A

Thank you

Nenad Bozic@NenadBozicNs

SmartCatwww.smartcat.io

@SmartCat_io