Types of Databases

As we discussed earlier, databases are divided into two types: relational and non-relational. Let’s discuss these types in detail.

Relational databases

Relational databases adhere to particular schemas before storing the data. The data stored in relational databases has prior structure. Mostly, this model organizes data into one or more relations (also called tables), with a unique key for each tuple (instance). Each entity of the data consists of instances and attributes, where instances are stored in rows, and the attributes of each instance are stored in columns. Since each tuple has a unique key, a tuple in one table can be linked to a tuple in other tables by storing the primary keys in other tables, generally known as foreign keys.

A Structure Query Language (SQL) is used for manipulating the database. This includes insertion, deletion, and retrieval of data.

There are various reasons for the popularity and dominance of relational databases, which include simplicity, robustness, flexibility, performance, scalabilityTraditional databases are vertically scalable. Vertical scaling has limits. One might reach a point when more compute, memory, storage, or networking capability could not be added to a single node., and compatibility in managing generic data.

Relational databases provide the atomicity, consistency, isolation, and durability (ACID) properties to maintain the integrity of the database. ACID is a powerful abstraction that simplifies complex interactions with the data and hides many anomalies (like dirty reads, dirty writes, read skew, lost updates, write skew, and phantom reads) behind a simple transaction abort.

But ACID is like a big hammer by design so that it’s generic enough for all the problems. If some specific application only needs to deal with a few anomalies, there’s a window of opportunity to use a custom solution for higher performance, though there is added complexity.

Let’s discuss ACID in detail:

• 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 ...