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MongoDB I

NoSQL DB

Categories

  • Document DB (MongoDB)
  • Key-value DB (Redis, *Speed)
  • Column-family DB (Cassandra)
  • Graph DB (Neo4J)

Document DB

Contains information in any format as JSON

  • Document - {"name":"user", "desc": "employee"}
  • Collection - Set of documents

Benefits

  • Availability
  • Consistency
  • Partion tolerance
  • Ease of deployment
    • No object-relation mapping required

Format

MongoDB store the information in BSON (Binary JSON format)
  • Contains about the type of a field value
  • Primitive types are supported as date time, raw binary, ObjectId

ObjectId 

By default MongoDB assign an id if you don't declare one


{
    "_id" : ObjectId("234234234"),
    "name" : "pizza" ,
     "desc" : "pepperoni"
}

  • 4- digits : timestamp
  • 3 - machine 
  • 2 - proc Id
  • 3 - increment

  • id.getTimestamp()  -  returns the timest in ISO formatpe: 

Commands 

  • Start DB
    • Type: mongo
  • DB
    • Show the current DB
  • use
    • Change the DB that has to be used
  • db.help();
    • Shows all the available commands
  • db.<colletion_name>.insert
    • Create a collection
  • db.<colletion_name>.find()
    • Show all the collections
  • db.<colletion_name>.find().pretty()
    • Show  all the collections in a better format
  • getTimestamp()
    • Show the date when the object was inserted

Installation

  • Download and install mongoDB
    • Create a folder named:
      • data
      • log
    • Create a config mongo.config
      • Type: dbpath=C:\Program Files\MongoDB\data
      • logpath=C:\Program Files\MongoDB\log
      • diaglog=3
  • By standart
    • Create a folder named mongodb 
    • Create a subfolder named data
  • From the console move to data and start Mongo
      • Type:  mongod --dbpath = data
  • Start
    • Type in another console:  mongo
    • Select DB
      • Type: use <DB Name>

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