Transactional databases store data in rows rather than columns to read and write data quickly. A transactional database maintains data integrity by relying on ACID (atomicity, consistency, isolation, durability) properties. ACID ensures that a database is restored to its original state if a transaction fails. Transactional databases are ideal for applications where data integrity is critical such as banking, financial services, and healthcare.
How Do Transactional Databases Work?
Transactional databases, also known as OLTP (Online Transaction Processing) databases, are designed to handle the constant, high-volume processing of transactions that occur in businesses, such as sales, inventory management, and financial transactions. Transactional databases use a four-step process called ACID:
Atomicity: Ensures that all transactions occur as a single unit. If any part fails, the entire transaction rolls back.
Consistency: The database is consistent, meaning the data always reflects the real world.
Isolation: Transactions are isolated, meaning that one transaction can only see the changes made by another once the second transaction completes.
Durability: Once the database commits a transaction, the changes to the data are permanent. The database will not roll back even if it experiences a system failure.
Here’s an example of how a transactional database works:
Let’s say you purchase something online. You enter your credit card information and click “submit.” The database will then start a transaction to update your account balance and create a new order record. If the transaction fails, for example, if your credit card information is invalid, the database will roll back the transaction, and your account balance will not be updated.
Transactional databases are essential for applications where data integrity is critical. They ensure that the data in the database is always accurate and consistent, even if there are system failures or errors in the application code.
Types of Transactions
There are different types of transactions in the context of transactional databases. These include:
ACID Transactions: These are the most common transactions. They guarantee four properties: atomicity, consistency, isolation, and durability.
Non-ACID Transactions: These transactions do not guarantee all four ACID properties. You can use them in applications where performance is more important than data integrity.
XA Transactions: These non-ACID transactions interact with distributed databases. They guarantee atomicity, consistency, and durability, but not isolation.
Batch Transactions: These transactions process large batches of data. You can use them in data warehousing and data mining applications.
Here is a table that summarizes the different types of transactions:
|ACID Transactions||Atomicity, Consistency, Isolation, Durability|
|Non-ACID Transactions||Atomicity, Consistency, Durability (may not have Isolation)|
|XA Transactions||Atomicity, Consistency, Durability|
|Batch Transactions||Atomicity, Consistency, Durability|
The type of transaction you use will depend on the specific requirements of your application. If you need to guarantee all four ACID properties, then you should use an ACID transaction. If performance is more important than data integrity, you can use a non-ACID transaction.
You can learn more about how transactions work within Couchbase here.
Benefits of Transactional Databases
Because of how they store data, transactional databases can manage large volumes of data and process transactions quickly. They also offer several benefits, which include:
Data integrity: Transactional databases ensure that data is always accurate and consistent. They can do this because transactions are atomic, meaning that all changes made by a transaction are either committed or rolled back. If any part fails, the entire transaction rolls back, and the database remains in its original state.
Reliability: Transactional databases can withstand system failures and errors in the application code. They have this capability because transactions are durable, meaning that once the database commits a transaction, the changes to the data are permanent. The database will not roll back even if a system failure occurs.
Performance: Because of their ACID properties, transactional databases can be very efficient, especially for applications that frequently manipulate data.
Scalability: You can scale transactional databases to accommodate large volumes of data due to their design which allows for distribution across multiple servers.
Use Cases for Transactional Databases
Transactional databases are used in applications where data integrity is critical. Here are some of the most common use cases for transactional databases:
Banking: Transactional databases are used in banking applications to ensure that financial transactions are accurate and consistent. For example, you can use a transactional database to process a credit card transaction or to transfer money from one bank account to another.
Retail: Transactional databases are used in retail applications to track inventory and process sales transactions. For example, you can use a transactional database to track the number of items in stock or to process a customer’s purchase.
Healthcare: Transactional databases are used in healthcare applications to track patient records and process medical transactions. For example, you can use a transactional database to track a patient’s medical history or to process a prescription.
E-commerce: Transactional databases are used in e-commerce applications to process orders and track inventory. For example, you can use a transactional database to process a customer’s order or to track the number of items in stock.
Logistics: Transactional databases are used in logistics applications to track shipments and manage inventory. For example, you can use a transactional database to track a shipment’s location or manage a warehouse’s inventory.
Manufacturing: Transactional databases are used in manufacturing applications to track production orders and manage inventory. For example, you can use a transactional database to track a production order’s status or manage the inventory of raw materials.
These are just a few of the many use cases for transactional databases. Any application where data integrity is critical could benefit from using a transactional database.
NoSQL for Transactions
Using ACID transactions in a NoSQL database depends on the specific use case and the trade-offs between consistency, availability, and partition tolerance. Because the design of NoSQL databases frequently conflicts with ACID properties, they don’t always support ACID transactions. However, Couchbase, a NoSQL database, has historically supported atomic single-document operations and optimistic and pessimistic locking and semi-recently added fast transactional support. You can read more about how we did that here.
Transactional databases are critical for businesses that must process a high volume of transactions with accuracy. Due to their reliance on ACID properties, they provide a reliable and secure way to manage data and maintain the integrity of transactions while offering scalability and flexibility to accommodate changing business needs. Overall, transactional databases and ACID transactions are essential tools for businesses that need to manage and process large volumes of data reliably and efficiently.
To continue learning more about transactional databases and using transactions within Couchbase, you can review these resources: