Lecture 23 10/21/15. CMPSC431W: Database Management Systems. Instructor: Yu- San Lin

Transcription

1 CMPSC431W: Database Management Systems Lecture 23 10/21/15 Instructor: Yu- San Lin Course Website: hcp:// 1

2 INTRODUCTION TO NOSQL DATABASE 2

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4 What is NoSQL? NoSQL stands for It is a non- relaronal database management systems Designed for distributed data stores where very large scale of data storing is needed Data storing nowadays may not require fixed schema, avoid join operarons and typically scale horizontally 4

5 Who uses NoSQL? 5

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7 Why NoSQL? NoSQL data modeling o[en starts from the applicaron- specific queries: RelaRonal modeling: What answers do I have? NoSQL data modeling: What ques4ons do I have? NoSQL data modeling o[en requires a deeper understanding of data structures and algorithms than relaronal database modeling does and are first- class cirzens NoSQL solurons are surprisingly strong for hierarchical or graph- like data modeling and processing. 7

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9 RDBMS v.s. NoSQL RDBMS Structured and organized data Structured query language (SQL) Data and its relaronships are stored in separate tables. Data ManipulaRon Language, Data DefiniRon Language Tight Consistency BASE TransacRon NoSQL Stands for Not Only SQL No declararve query language No predefined schema Key- Value pair storage, Column Store, Document Store, Graph databases Eventual consistency rather ACID property Unstructured and unpredictable data Theorem PrioriRzes high performance, high availability and scalability 9

10 CAP Theorem : data in the database remains consistent a[er the execuron of an operaron, e.g., a[er an update operaron, all clients see the same data : system is always on, no downtown : system conrnues to funcron even the communicaron among the servers is unreliable 10

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12 NoSQL Pros & Cons Pros High scalability Distributed compurng Lower cost Schema flexibility, semi- structure data No complicated relaronships Cons No Limited query capabilires (so far) 12

13 Types of NoSQL Databases database database databases databases * There is not a single soluron that is becer than the others. 13

14 Key- Value Database The most basic types of NoSQL databases Designed to handle huge amount of data Based on Amazon s Dynamo paper Allows developer to store data Database stores data as where each key is unique and the value can be string, JSON, BLOB (basic large object) etc. 14

15 Key- Value Database (cont.) A key may be strings, hashes, lists, sets, sorted sets Key- value stores can be used as collecrons, dicronaries, associarve arrays etc. Key- value stores follow the and aspects of CAP theorem Suitable for: shopping cart contents, individual values like color schemes 15

16 Key- Value Database (cont.) 16

17 Example of Key- Value Database Amazon Dynamo 17

18 Column Family Database Primarily work on columns and every column is treated individually Values of a single column are stored conrguously Column stores data in column specific files In column stores, query processors work on columns too 18

19 Column Family Database (cont.) All data within each column datafile have the same type which makes it ideal for compression Column stores can improve the performance of queries as it can access specific column data High performance on queries, e.g., COUNT, SUM, AVG, MIN, MAX Suitable for: customer relaronship management (CRM), library card catalogs 19

20 Column Family Database (cont.) 20

21 Examples of Column Family Database 21

22 Graph Database Stores data in Capable of elegantly represenrng any kind of data in a highly accessible way Is a collecron of and Each note represents an, and each edge represents a connecron or relaronship between two nodes 22

23 Graph Database (cont.) Every node and edge is defined by a unique idenrfier Each node knows its adjacent nodes As the number of nodes increases, the cost of a local step (or hop) remains the same 23

24 Graph databases (cont.) 24

25 RelaRonal Model v.s. Graph Model Rela9onal Model Tables Rows Columns Joins Graph Model VerRces and Edges set VerRces Key- value pairs Edges 25

26 Examples of Graph Database 26

27 Document Database A collecron of Data in this model is stored inside documents A document is a key value collecron where the key allows access to its value Documents are not typically forced to have a schema and therefore are flexible and easy to change 27

28 Document Database (cont.) Documents are stored into collecrons in order to group different kinds of data Documents can contain many different key value pairs, or key array pairs, or even nested documents 28

29 RelaRonal Model v.s. Document Model Rela9onal Model Tables Rows Columns Joins Document Model CollecRons Documents Key- value pairs N/A 29

30 Document Databases (cont.) 30

31 Examples of Document Databases 31

32 References Ilya Katsov, NoSQL Data Modeling Techniques, hcps://highlyscalable.wordpress.com/2012/03/01/ nosql- data- modeling- techniques/ Pramod Sadalage, NoSQL Databases: An Overview, hcp:// databases- overview NoSQL tutorial, hcp:// 32