NoSQL

Francesco ZitelliMay 2014

A new trend in data warehousing

What is NoSQL?

NoSQL is a category of database

management systems (DBMS)

NoSQL is non relational DB:

it means “Not only SQL”

BUT WHAT IS A

RELATIONAL DB?

AND WHAT IS SQL?

In a relational DB, information about an object

are scattered through different tables:

Image from: M. Fowler

SQL stands for structured query

language and it is used to

interrogate the relational DBs,

for example:

Select * from Member where Age > 30

Concept of NoSQL DBs

came with internet giants:

They needed a new kind of

DBMS able to deal with

enormous amount of data!

Why NoSQL?

BIG DATA!

Response time of relational DBs

is slower when we are dealing

with high volume of data

To overcome this we can

scale up the system…

But are we sure that

bigger is better?

Scale up Scale out

vs

Scaling up is expensive. But the problem

with scaling out is that SQL is even slower

in fetching all relevant data across

different machines...

SQL SQL

In NoSQL DBs, data object are

treated as aggregates and are

not spreaded across differents

tables. Similar aggregates are grouped

in the same cluster and located

in the same machine: this

reduces response time!

NoSQL DBs scales out better and

can leverage big data

They do not use SQL

language to query data

There is not a strict

schema for data structure

With NoSQL DBs, ACID

is not always guaranteed

But your application gain

in higher flexibility and

scalability

(atomicity, consistency,isolation, durability)

Better business

opportunities and

lower costs!

NoSQL are specialized to deal

with big amount of data

Most users still deal with

relatively compact data set:

conventional DBMS are still valid

Conclusion

We observe the coexistence

of different data models!

References[video] Introduction to NoSQL by Martin Fowler

[video] What is NoSQL ?