Explain briefly about ACID and BASE Database Transaction Models and what are the differences between them.

Database Transaction Models

• Database Transaction Models are a set of rules which determine how a database organizes, stores, and manipulates data.
• The two most common models are known by the acronyms ACID and BASE.
• Both these models come with their advantages and disadvantages and neither is always a perfect fit.

The ACID Model

• The ACID database transaction model ensures that a performed transaction is always consistent.

The ACID stands for:

Atomic –

• Each transaction is either properly carried out or the process halts and the database reverts to the state before the transaction started.
• This ensures that all data in the database is valid.

Consistent –

• A processed transaction will never endanger the structural integrity of the database.

Isolated –

• Transactions cannot compromise the integrity of other transactions by interacting with them while they are still in progress.

Durable –

• The data related to the completed transaction will persist even in the cases of network or power outages.
• If a transaction fails, it will not impact the manipulated data.

Example -

• This makes it a good fit for businesses that deal with online transaction processing such as financial institutions or online analytical processing such as data warehousing.
• Financial institutions will almost exclusively use ACID databases.
• Money transfers depend on the atomic nature of ACID.
• An interrupted transaction that is not immediately removed from the database can cause a lot of issues.
• Money could be debited from one account and, due to an error, never credited to another.

The BASE Model

• The rise of NoSQL databases provided a flexible and fluid way to manipulate data.
• As a result, a new database model was designed, reflecting these properties.
• The BASE database transaction model ensures high availability.

The BASE stands for:

Basically Available –

• Rather than enforcing immediate consistency, BASE-modelled NoSQL databases will ensure the availability of data by spreading and replicating it across the nodes of the database cluster.

Soft State –

• Data values may change over time in the absence of immediate consistency
• It breaks off with the concept of a database that enforces its consistency, delegating that responsibility to developers.

Eventually Consistent –

• The fact that BASE does not enforce immediate consistency does not mean that it never achieves it.
• However, until it does, data reads are still possible (even though they might not reflect the reality).

Example -

• Marketing and customer service companies who deal with sentiment analysis will prefer the elasticity of BASE when conducting their social network research.
• Social network feeds are not well structured but contain huge amounts of data that a BASE-modeled database can easily store.

ACID V/S BASE