NOSQL & JSON

2014/10/12 WU TIEN YANG

JSON

JSON JAVASCRIPT OBJECT NOTATION

• serializing data objects

• Human-readable,useful for data interchange

• useful for storing semistructured data

JSON

• Basic value

• number,string,boolean

• Objects{}

• label-value pairs

• Arrays[]

• list of value

LIVE DEMO JSON EDITOR ONLINE

JSON

Relational JSON

Structure TablesNest,label-value,array

Schema Fix Flexible

Queries simple expressive language XD,widely use

Ordering None Arrays

Implementation Native system NOSQL system

JSON JAVASCRIPT OBJECT NOTATION

• Sets of label-value pairs

• Arrays of values

• Base values from predefined types

JSON fileJSON parse program objects

syntactic error

WHEN JSON MEET PYTHON!

JSON

JSON PYTHON

Object dict

array list,tuple

str unicode

null none

number int,long,float

encoding: python -> json json.dumps()

decoding: json -> python json.loads()

LIVE DEMO

NOSQL

WHY WE CHOOSE NOSQL?

Relational DBMS face the problem!

problem: semi-structure data poor performance

problem: scaling difficult / expensive / impossible ->BIG DATA

NOSQL

• SQL : Traditional relational DBMS

• NOSQL = not only SQL

• MASSIVE!

NOSQL

• Flexibles schema

• Quicker / Cheaper to set up

• Massive scalability

• Relaxed consistency -high performance,availability

NOSQL system V.S Traditional relational DBMS

NOSQL

• Flexibles schema

• Quicker / Cheaper to set up

• Massive scalability

• Relaxed consistency -high performance,availability

NOSQL system V.S Traditional relational DBMS

no declarative query language -> more programming

Relaxed consistency ->fewer guarantees

NOSQL MAPREDUCE FRAMEWORK

• no data model,data stored in files

• specific function

• map(),reduce(),read(),write()

• system provides fault-tolerance,scability

NOSQL MAPREDUCE FRAMEWORK

• Map: divide problem into subproblems

• map(item) -> <key,value>pairs

• Reduce: do work on subproblems,combine result

• reduce(key,lists of value) -> result

NOSQL MAPREDUCE EXAMPLE

• record: User ID,URL,timestamp,additional-info

• task: Count number of accesses for each domain

• map(record) -> <domain,value>

• reduce(domain,lists of value) -> <domain,sum>

Web log analysis

NOSQL KEY-VALUE STORES

• extremely simple interface

• Data model: {key,value} pairs

• Operation : insert , update , delete

• implement : efficiency,scalability,fault-tolerance

• record distributed to nodes base on key

• eventual consistency

MONGODB

MONGODB NOSQL DATABASE

RDBMS MongoDB

Database Database

Table collection

Record/Row Document

Column Field

Primary Key _id

a record = a document

many documents = a collection

LIVE DOME TRY IT OUT !

REFERENCES

• Stanford University -DB introduction to Databases

• python library - storing json

• mongoDB