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CMPSC431W: Database Management Systems
Instructor: Yu-‐San Lin [email protected]
Course Website: hCp://www.cse.psu.edu/~yul189/cmpsc431w
Lecture 23 10/21/15
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INTRODUCTION TO NOSQL DATABASE
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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
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Who uses NoSQL?
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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.
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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
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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
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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)
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Types of NoSQL Databases
• ____________ database • ____________ database • ____________ databases • ____________ databases * There is not a single soluRon that is beCer than the others.
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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.
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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
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Key-‐Value Database (cont.)
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Example of Key-‐Value Database
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Amazon Dynamo
Column Family Database
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• 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
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
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Column Family Database (cont.)
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Examples of Column Family Database
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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
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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
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Graph databases (cont.)
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RelaRonal Model v.s. Graph Model
Rela9onal Model Graph Model Tables VerRces and Edges set Rows VerRces Columns Key-‐value pairs Joins Edges
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Examples of Graph Database
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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
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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
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RelaRonal Model v.s. Document Model
Rela9onal Model Document Model Tables CollecRons Rows Documents Columns Key-‐value pairs Joins N/A
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Document Databases (cont.)
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Examples of Document Databases
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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://www.thoughtworks.com/insights/blog/nosql-‐databases-‐overview
• NoSQL tutorial, hCp://www.w3resource.com/mongodb/nosql.php
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