Introduction to NOSQL databases
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The presentation provides an overview of NoSQL databases, including a brief history of databases, the characteristics of NoSQL databases, different data models like key-value, document, column family and graph databases. It discusses why NoSQL databases were developed as relational databases do not scale well for distributed applications. The CAP theorem is also explained, which states that only two out of consistency, availability and partition tolerance can be achieved in a distributed system.
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Introduction to NOSQL databases
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- 2. 2What is covered in this presentation? A brief history of databases NoSQL WHY, WHAT & WHEN? Characteristics of NoSQL databases Aggregate data models CAP theorem 5 February 2016 Ashwani Kumar NOSQL Databases
- 3. Introduction Database - Organized collection of data DBMS - Database Management System: a software package with computer programs that controls the creation, maintenance and use of a database Databases are created to operate large quantities of information by inputting, storing, retrieving, and managing that information. 5 February 2016 Ashwani Kumar NOSQL Databases 3
- 4. 5 February 2016 Ashwani Kumar NOSQL Databases A brief history 4
- 5. • Benefits of Relational databases: Designed for all purposes ACID Strong consistancy, concurrency, recovery Mathematical background Standard Query language (SQL) Lots of tools to use with i.e: Reporting services, entity frameworks, ... 5 February 2016 Ashwani Kumar NOSQL Databases Relational databases 5
- 6. 5 February 2016 Ashwani Kumar NOSQL Databases SQL databases 6
- 7. 5 February 2016 Ashwani Kumar NOSQL Databases RDBMS 7
- 8. But... Relational databases were not built for distributed applications. Because... Joins are expensive Hard to scale horizontally Impedance mismatch occurs Expensive (product cost, hardware, Maintenance) 5 February 2016 Ashwani Kumar NOSQL Databases NoSQL why, what and when? 8
- 9. And.... It’s weak in: Speed (performance) High availability Partition tolerance 5 February 2016 Ashwani Kumar NOSQL Databases NoSQL why, what and when? 9
- 10. 5 February 2016 Ashwani Kumar NOSQL Databases Why NOSQL now?? Ans. Driving Trends 11
- 11. 5 February 2016 Ashwani Kumar NOSQL Databases Side note: RDBMS performance 12
- 12. But.. What’s NoSQL? A No SQL database provides a mechanism for storage and retrieval of data that employs less constrained consistency models than traditional relational database No SQL systems are also referred to as "NotonlySQL“ to emphasize that they do in fact allow SQL-like query languages to be used. 5 February 2016 Ashwani Kumar NOSQL Databases But.. What’s NoSQL? 13
- 13. NoSQL avoids: Overhead of ACID transactions Complexity of SQL query Burden of up-front schema design DBA presence Transactions (It should be handled at application layer) Provides: Easy and frequent changes to DB Fast development Large data volumes(eg.Google) Schema less 5 February 2016 Ashwani Kumar NOSQL Databases Characteristics of NoSQL databases 14
- 14. 5 February 2016 Ashwani Kumar NOSQL Databases NoSQL why, what and when? 10
- 15. 5 February 2016 Ashwani Kumar NOSQL Databases NoSQL is getting more & more popular 15
- 16. In relational Databases: You can’t add a record which does not fit the schema You need to add NULLs to unused items in a row We should consider the datatypes. i.e : you can’t add a stirng to an interger field You can’t add multiple items in a field (You should create another table: primary-key, foreign key, joins, normalization, ... !!!) 5 February 2016 Ashwani Kumar NOSQL Databases What is a schema-less datamodel? 16
- 17. In NoSQL Databases: There is no schema to consider There is no unused cell There is no datatype (implicit) Most of considerations are done in application layer We gather all items in an aggregate (document) 5 February 2016 Ashwani Kumar NOSQL Databases What is a schema-less datamodel? 17
- 18. NoSQL databases are classified in four major datamodels: • Key-value • Document • Column family • Graph Each DB has its own query language 5 February 2016 Ashwani Kumar NOSQL Databases Aggregate Data Models 18
- 19. Simplest NOSQL databases The main idea is the use of a hash table Access data (values) by strings called keys Data has no required format data may have any format Data model: (key, value) pairs Basic Operations: Insert(key,value), Fetch(key), Update(key), Delete(key) 5 February 2016 Ashwani Kumar NOSQL Databases Key-value data model 19
- 20. The column is lowest/smallest instance of data. It is a tuple that contains a name, a value and a timestamp 5 February 2016 Ashwani Kumar NOSQL Databases Column family data model 20
- 21. Some statistics about Facebook Search (using Cassandra) MySQL > 50 GB Data Writes Average : ~300 ms Reads Average : ~350 ms Rewritten with Cassandra > 50 GB Data Writes Average : 0.12 ms Reads Average : 15 ms 5 February 2016 Ashwani Kumar NOSQL Databases Column family data model 21
- 22. Based on Graph Theory. Scale vertically, no clustering. You can use graph algorithms easily Transactions ACID 5 February 2016 Ashwani Kumar NOSQL Databases Graph data model 22
- 23. • Pair each key with complex data structure known as data structure. • Indexes are done via B-Trees. • Documents can contain many different key-value pairs, or key-array pairs, or even nested documents. 5 February 2016 Ashwani Kumar NOSQL Databases Document based data model 23
- 24. 5 February 2016 Ashwani Kumar NOSQL Databases Document based data model 24
- 25. 5 February 2016 Ashwani Kumar NOSQL Databases SQL vs NOSQL 25
- 26. • We need a distributed database system having such features: • – Fault tolerance • – High availability • – Consistency • – Scalability Which is impossible!!! According to CAP theorem 5 February 2016 Ashwani Kumar NOSQL Databases What we need ? 26
- 27. We can not achieve all the three items In distributed database systems (center) 5 February 2016 Ashwani Kumar NOSQL Databases CAP theorem 27
- 28. 5 February 2016 Ashwani Kumar NOSQL Databases CAP theorem 28
- 29. 5 February 2016 Ashwani Kumar NOSQL Databases Conclusion…. 29
- 30. 5 February 2016 Ashwani Kumar NOSQL Databases References.. nosql-database.org/ https://www.mongodb.com/nosql-explained www.couchbase.com/nosql-resources/what-is-no-sql http://nosql-database.org/ "NoSQL DEFINITION: Next Generation Databases mostly addressing some of the points: being non-relational, distributed, open- source and horizontally scalable“ NoSQL distilled, Martin Fowler Please like and follow at www.slideshare.net/AshwaniKumar274 30
- 31. 5 February 2016 Ashwani Kumar NOSQL Databases 31