Database Systems

ACID Properties of Transactions -- source

These are properties of database transactions. Transactions are used in transactional databases, which describe most relational database management systems. Necessary design where sequence of data is important, and for critical operations.

• atomicity requires each transaction be "all or nothing" (occurs in whole or not at all)
• generally implemented with some mechanism that indicates which transactions have started and finished
• Operating systems use open(2) and flock(2)
• consistency ensures that any transaction will bring the database to a valid state based on set rules
• isolation ensures that concurrent operations should act as if they were executed serially (one after another)
• durability ensures that commited transactions remain in the database even in the event of failure

Firebase Realtime Database

Stores and syncs data in a NoSQL cloud database. Data syncs across all clients in realtime, by pushing data to clients when changes are made to the database.

• allows you to build server-less apps
• offers offline support
• can be used to store remote config, that pushes to services when changed

Firebase's database store information as JSON objects; it's a JSON Tree.

• no tables or records
• Firebase Storage (component of firebase) stores files