Data is the lifeblood of any business. It’s the key to success and is essential for gathering intelligence, making decisions, and improving operations.
A business relies on its data and applications to operate every day. But what happens when one of their databases or systems fails?
All of the critical business information and data could be at risk.
Fortunately, there are ways to prevent this from happening. One of the most effective methods for protecting business data is database replication. It is something that every small, medium and large business must adapt to survive in the competition.
In this article, I’ll discuss what data replication is, how it works, and other important aspects.
So, let’s get started!
What Is Database Replication?
Transferring data from a source database to one or more destination databases is known as database replication. It often entails copying or streaming data from one database to another so that all users can access synchronized data no matter what system they use to view it.
If data changes, a data replication tool will ensure that the changes are also implemented in the destination database. As a result, a distributed data storage network with greater availability across multiple locations is created, allowing everyone to access vital and relevant data quickly.
Using a data replication solution, you are likely to notice an improvement in data consistency across each node, reduced data redundancy, more significant data reliability, and, eventually, an increase in performance.
Database replication can occur in real-time, as data is created, edited, and destroyed on the source database or as part of a batch operation.
How Does Data Replication Work?
Database replication can be performed once or as a continuous process. It involves all data sources of an organization, and a distributed database management system (DDBMS) is used to transfer or distribute data to all the sources.
Any changes, additions, and deletions done on the source database are automatically synced to the other target databases if those changes are required. According to the conventional Publisher-Subscriber software paradigm, one or more “publishers” and “subscribers” are involved in the data replication process.
A “publisher” is a system or the source database on which changes are made, and a “subscriber” is a system on which the changes are replicated.
Any modifications performed on a “publisher” system are then replicated to “subscriber” databases. Users can also make changes in subscriber databases, which are then replicated in the publisher database. This distributes the changes to all other subscribers in the network if the system is bi-directional.
Moreover, most subscribers have a fixed link with the publisher, allowing changes or upgrades to occur automatically without manual intervention. These updates may happen in batches at regular intervals or could be triggered and applied in real-time.
Types of Database Replication
Some of the types of database replication are:
#1. Full-Table Replication
Full-table replication creates a copy of the complete source database to the target storage. It moves rows from the publisher to the subscriber, including new, modified, and existing rows.
However, this replication approach is linked with a high maintenance cost due to the computing power and network bandwidth requirements required to copy everything. It strains the network and can create replication delays, especially when the data volume is larger.
#2. Snapshot Replication
A snapshot of the source database is used in this database replication to replicate data in the target destination database. It does not consider data changes such as new, updated, or deleted; instead, it creates a copy of what it collects at the time.
When data changes are very few, this replication technique is preferable. It is significantly quicker than full-table replication, but it doesn’t keep track of hard-deleted data.
#3. Merge Replication
Merge replication is a process that transfers and distributes database objects and data from one database to another with database synchronization. It is complex since this process allows subscribers and publishers to change the database, resulting in frequent version-related data conflicts.
Merge agents deployed on the servers synchronize all changes and follow a predefined conflict resolution process to resolve any data conflict.
#4. Key-Based Incremental Replication
Key-based incremental replication checks keys or indexes in a database to look for changes like delete, new and updated. The replication mechanism then copies only the required replication keys to the replica database to reflect the changes since the last update. These keys are usually a timestamp, a date, or an integer.
Since only indicated changes are replicated to the replica database, the process is quicker. Unfortunately, this method does not enable hard deletes because the critical value is removed by erasing the primary database record.
#5. Log-based Incremental Replication
This type of database replication duplicates data according to the database’s binary log file. Upon inspecting the binary log file, it will provide you with information on changes performed to the primary database, for instance, updates, inserts, or deletes. Next, the same modifications or updates are performed in your destination database.
This is one of the most widely used methods of data replication as it’s efficient, especially for static databases. In addition, most database providers support it, including Oracle, MongoDB, MySQL, and PostgreSQL.
#6. Transactional Replication
When there is a new development in the source data, transactional replication moves all existing data from the source database to the target location. Then it executes the same transaction in the replicas.
Though it is an efficient replication method, the models find usage mostly in read activities and may not allow creating, deleting, or updating operations.
Why Is DB Replication Important?
Database replication is important due to the following reasons:
Data Reliability and Availability
Data replication promotes data availability. It plays an important role when a server fails under unusual circumstances by providing database backups. This way, it can save your day because data is available in other locations. Also, it enhances data reliability by keeping relevant, latest data saved safely in multiple servers.
Disaster Recovery
Database replication is helpful during a server failure scenario. It’s a wonderful disaster management and recovery technique since it replicates and stores data and recent changes at other server locations instead of relying on a single server.
Server Performance
Data access is much faster when data is processed and operated on several servers. Furthermore, administrators can free up processing cycles on the original server for more resource-intensive writing operations by directing all data read operations to a replica.
Better Network Performance
Keeping multiple copies of the same data in different locations may reduce data access latency because you may retrieve the relevant data from the location where the transaction is executed.
For instance, users in European countries may feel latency issues while accessing data from Australian data centers. Thus, placing a replica of this data close to the user can improve access times while balancing the network strain.
Improved Test System Performance
Database replication streamlines data distribution and synchronization for test systems that require quick access for speedier decision-making.
Database Backup vs. Database Replication
Both database backup and database replication vary in several ways. Some of them are as follows:
- Database backups must be reconstructed and restored before they can be used. Unlike database backups, data replication does not require reconstruction and can be used immediately.
- Database backups consist of files or folders, database data files, and application files, depending on organizational backup-restore protocols. In contrast, database replication is often used to duplicate complete volumes or file systems, databases, and applications.
- Backup and replication are both data protection measures. The former concerns lowering Recovery Point Objectives (RPOs) and preventing data loss. While the latter is designed to reduce Recovery Time Objectives (RTOs), assuring business continuity and minimizing downtime.
- Database backup is a low-cost method of avoiding total data loss. It is essential for compliance and does not guarantee operational continuance. On the contrary, replication ensures that business applications and processes are always available, even after a power outage.
- Database backup is concerned with compliance and granular recovery, such as the long-term storage of company records. On the other hand, database replication and recovery focus on disaster recovery, the speedy and easy resumption of operations following an outage or corruption.
- Database backup is commonly utilized in the workplace for everything from production servers to desktops. On the contrary, database replication is frequently used for mission-critical applications that must always be available.
Techniques of Database Replication
Organizations can replicate data by following a precise technique to move the data. These strategies differ from the types of replication described above.
#1. Full database replication
Full Database Replication replicates an entire database for use on different hosts. This ensures the most significant amount of data redundancy and availability. For global enterprises, this allows users in Asia to access the same data as their counterparts in North America at the same speed. If the Asian server fails, users can utilize their European or North American servers as a backup.
However, the drawback of this technique is the slow updation procedure. It is also difficult to keep each file location consistent, which is significant if the data continuously changes.
#2. Partial database replication
Partial Database Replication is the process through which data in a database is separated into pieces and saved in different locations, dependent on the relevance of each site.
Insurance adjusters, financial counselors, and sales professionals profit from partial replication. These employees can carry the partial databases on other devices or laptops and routinely synchronize them with a central server.
For analysts, it may be more economical to maintain European data in Europe, Australian data in Australia, etc. This means keeping the data close to the consumers while keeping a comprehensive data set at headquarters for high-level analysis.
Drawbacks of Database Replication
Although data replication may bring significant value to your job and firm, it also comes with the following drawbacks:
Higher costs
When data is replicated and stored in multiple locations, it requires more storage space and computing resources. This increased demand for hardware and computing resources can lead to higher costs, including purchasing and maintaining additional storage devices, servers, and network infrastructure.
Time constraints
Data replication is a complex process that involves copying data from one location to multiple other locations and maintaining consistency across all copies. This process can take significant time, especially for organizations that must replicate large amounts of data.
Bandwidth
As the volume of data being replicated increases, the bandwidth requirements also go up, which can strain network resources.
Inconsistent data
When replicating data in a distributed environment, there is a risk of data becoming out of sync if updates are not done consistently across all replicas. This can result in inconsistent data and may require extra effort to resolve.
Use Cases of Database Replication
There are many cases where data replication can be used, such as:
Load balancing
By replicating data to multiple servers, the load is distributed across these servers to improve its performance. Thus, load balancing ensures that a single server is not overwhelmed by too many requests and that the system remains available and responsive even during high-traffic periods.
Data warehousing
A data warehouse is a centralized repository for storing large amounts of data from multiple sources. Replicating data from these sources to the data warehouse allows organizations to analyze and report on their data in a centralized and organized manner.
Cross-regional deployment
Replicating data to multiple regions allows organizations to improve data accessibility and redundancy. If a region experiences an outage, the data can still be accessed from another region. Additionally, having data in multiple regions can help improve access speed for users in different parts of the world.
Backup and archiving
Replicating data to secondary storage helps organizations keep a long-term copy of their data. This allows them to access the data easily and ensures that it is not lost even if the primary storage fails.
Data synchronization
Replicating data between multiple systems helps ensure that the data remains synchronized, consistent, and up-to-date everywhere. This is important for applications such as e-commerce, where the same data needs to be accessible from multiple systems.
Multi-site collaboration
Replicating data between multiple sites allows organizations to share data in real-time, enabling collaboration and increased productivity. This is particularly useful for organizations with teams in multiple locations or companies that need to share data with partners or customers.
Learning Resources
Here are a few learning resources to help you understand the topic more:
#1. Database Replication by Bettina Kemme
This book will help you understand different concurrency and replica control mechanisms and issues concerning it.
#2. Database Replication: A Complete Guide:
This book will prepare you to face database replication challenges by explaining and answering your questions.
Conclusion
Data Replication is an underappreciated strategy in today’s fast-growing, data-driven world. So, if you are a business owner, you would be surprised by its benefits.
However, as the number of sources and destinations grows, businesses must be prepared to face the challenges that come with it. That is why a reliable, scalable data replication strategy may come in handy for you.
You may also explore some useful database monitoring software to analyze performance.
