Databases

RDBMS

ACID

• Atomicity: A transaction is considered an atomic unit. Therefore, either all the statements within a transaction will successfully execute, or none of them will execute. If a statement fails within a transaction, it should be aborted and rolled back.

• Consistency: At any given time, the database should be in a consistent state, and it should remain in a consistent state after every transaction. For example, if multiple users want to view a record from the database, it should return a similar result each time.

• Isolation: In the case of multiple transactions running concurrently, they shouldn’t be affected by each other. The final state of the database should be the same as the transactions were executed sequentially.

• Durability: The system should guarantee that completed transactions will survive permanently in the database even in system failure events.

Benifits

• Flexibility

• Reduced Redundancy (Via Normalizations)

• Concurrency

• Integration

Drawbacks

• Impedance mismatch is the difference between the relational model and the in-memory data structures.

No-SQL

Types

• Key-Value Store. - Dynamodb

• Document - Mongodb

• Column Oriented / Columner - Cassandra

• Graph - Neo DB