AN introduction to nosql databases

Transcription

1 AN introduction to nosql databases Terry

2 Purpose of this presentation? It is important for a data scientist / data engineer to have the right tool for the right job. We will look at an overview of the major types of NoSQL databases and why we might want to use them

3 What is NoSQL? Where did the term come from? NoSQL!= A database that does not use SQL NoSQL!= Not only SQL NoSQL was an accident - but it has stuck.

4 What is NoSQL? What are no SQL Databases? > Not using the relational model (nor the SQL language) > Open source > Designed to run on large clusters > Based on the needs of 21st century web properties > No schema, allowing fields to be added to any record without controls (Schema-on-read)

5 A history of databases. Databases have been around since the 1960s Hierarchical Relational NoSQL 2000+

6 What is NoSQL? - Relational databases A short history of relational databases E.F. CODD Father of relational theory (1970) A Relational Model of Data for Large Shared Data Banks Relational model/theory Further developed by Codd & C Date

7 What is NoSQL? - Relational databases Codd devised 12 rules (there are 13 ) For how a relational database should work. Any idea why there are actually 13 rules?

8 What is NoSQL? - Relational databases Database building blocks: Database Table Columns Rows Cell Logical structure Holds data (Columns and rows) Attributes about that data A single set of attributes where a row and column intercept.

9 What is NoSQL? - Relational databases 1. Entity 2. Relationship 3. Diagram 4. ERD

10 What is NoSQL? - Relational databases Normal form Devised by Codd: 1 st - Eliminate repeating groups, Table for related data, Add Primary key 2 nd - Every attribute should be related its own primary key 3 rd - No functional dependency

11 What is NoSQL? - Relational databases 3 rd Normal form

12 What is NoSQL? - Relational databases 3 rd Normal form

13 What is NoSQL? - Relational databases ACID compliance A C I D - Atomic - Consistent - Isolated - Durable

14 What is NoSQL? - Relational databases Commonly used for an integration layer

15 What is NoSQL? - Relational databases It has SQL

16 What is NoSQL? - Relational databases SELECT - Which columns do you want - Req FROM - Where are they coming from - Req WHERE - Apply filters to limit rows - Opt GROUP BY - Aggregate data - Opt HAVING - Apply filters to limit groups - Opt ORDER BY - Sort the data -Opt

17 What is NoSQL? - Relational databases SELECT SELECT BusinessEntityID,PersonType,NameStyle FROM Person.Person Column names What is being selected From where (Column delimiter) Schema.TableName

18 What is NoSQL? - Relational databases Problems with Relational databases 3NF means many joins Poor support for partitions (nodes) Not Web scale Scale up not out Impedance mismatch

19 What is NoSQL? NoSQL to the rescue well, not really.

20 What is NoSQL? NoSQL can be generalised using Brewers CAP Theorem Pick 2 Consistency Availability Partition Tolerance

21 What is NoSQL? NoSQL Databases come in 4 main types 1. Key/Value 2. Document 3. Column-store 4. Graph

22 What is NoSQL? - Key/Value Keys and values JSON Schema-less / schema-on-read Used for caching

23 What is NoSQL? - Document Keys and values (as a document) JSON Schema-less / schema-on-read Used for completed orders etc

24 What is NoSQL? Columnfamily Keys and column familes Columns which are related (Customer, Product) Used for completed orders etc

25 What is NoSQL? Graph Nodes, edges, relationships K/V pairs Used for social graphs LinkedIn Really hard to do in a relational database

26 What is NoSQL? What is the benefit? Designed from the ground up for a particular function. Not multi-purpose

27 What is NoSQL? Impedance mismatch

28 What is NoSQL? Relational is DEAD long live NoSQL.. well, not really.

29 Hierarchical Relational NoSQL 2000+

30 What is NoSQL? Polyglot persistence Pick the right database for the right job

31 What is NoSQL? Polyglot Persistence Martin Fowler

32 0. Relational database 1. Key/Value 2. Document 3. Column-store 4. Graph Right database for the right job

33 Questions?