Cloud Computing Lab: MongoDB NoSQL Database Assignment

NoSQL Databases

• NoSQL databases store data differently than relational tables and provide flexible schemas.
• They scale easily with large amounts of data and high user loads.

Document Databases

• Organize documents into groups called collections, analogous to tables in relational databases.
• Maintain sets of key-value pairs within a document.
• Examples: MongoDB.

MongoDB

• A document-oriented NoSQL database.
• Uses MongoDB commands/operations such as:
  • use db to switch to a database.
  • help to display command help.
  • show dbs to list available databases.
  • show collections to list available collections.
  • db.createCollection(“sample”) to create a new collection.
  • db.sample.insertOne() and db.sample.insertMany() to insert documents.
  • db.sample.find() to retrieve documents.
  • updateOne() and updateMany() to update documents.
  • deleteOne() and deleteMany() to delete documents.

MongoDB and Map-Reduce

• Map-reduce is a data processing paradigm for condensing large volumes of data into useful aggregated results.
• MongoDB uses the mapReduce command for map-reduce operations.
• The map phase applies to each input document, emitting key-value pairs.
• The reduce phase collects and condenses aggregated data for keys with multiple values.
• All map-reduce functions in MongoDB are JavaScript functions:
  • map maps a value with a key and emits a key-value pair.
  • reduce reduces or groups all documents having the same key.
  • out specifies the location of the map-reduce query result.
  • query specifies the optional selection criteria for selecting documents.