Database Replication: 6 Comprehensive Aspects

on Data Integration, Data Replication, Relational Database, Tutorials • September 7th, 2020 • Write for Hevo

Nothing is more important than data in today’s world. How horrifying it would be to lose important data at the business level because you have suffered a system or server crash. The importance of Data Replication is an adamant thing that every small, medium or large organization has to adapt to survive in the competition. Data Replication can be a tricky thing to manage as it depends upon the size of data, type of DBMS, and how frequently data is being updated.

In this blog, you will learn about Database Replication, types of Database Replication, how it is done, and its importance. Moreover, the blog will explain the advantages and challenges of Database Replication and list down the popular tools that can simplify the Replication process for you. Read along to learn more about this essential process!

Table of Contents

Introduction to Database Replication

Database Replication Logo
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Data Replication can be simply described as the task of making copies of the data stored in Databases on one server and regularly transferring those copies to other Databases located on different servers. The idea is to store the same data in multiple locations so that everyone connected to it distributes the system and has access to the same shared data. In this way, all users share the same level of information. The result is a Distributed Database System in which users can quickly access data relevant to their tasks without interfering with the work of others. 

The key aspect of this process is that this copying of data must occur very frequently so that any new changes in one Database could be reflected throughout the Distributed System. Organizations use different types of Data Replications like Full Replication, Incremental Replication, and Log-based Replication depending on their needs, resources, and the extent of data they wish to copy.

To learn more about Database Replication. visit here.

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Database Replication vs Mirroring

Mirroring involves, creating a backup Database Server as a safety measure for the Primary Database Server. This is done to safeguard the data availability of your company. So, in a situation where the Primary Database Server is down, the Mirrored Database Server will act as the main source of data. it is important to note that, out of the Primary Database Server and the Mirrored Database Server, only one will be active at a time. The Database Mirroring process is shown in the below image.

Database Mirroring
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Database Replication, on the other hand, means storing multiple copies of a Database across multiple geographic locations. The classic example of Replication is File Servers that are copied and stored across all continents, enabling users to download files from the closest location to avoid network delays and any slow responses. The Database Replication process is shown in the below image.

Database Replication
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The following points will further explain the difference between Database Replication and Database Mirroring:

  • Database Replication is implemented on Database Objects while Mirroring involves the whole Database.
  • When it comes to Distributed Database Systems, Mirroring can’t be implemented. Data Replication, however, thrives in such situations.
  • The main objective of Mirroring is to create a backup while Data Replications aims at increasing the distribution efficiency of data.
  • Data Replication is relatively cheaper as compared to Mirroring.

Advantages of Database Replication

The process of Data Replication can provide the following major advantages to your business:

  • Ensure a consistent copy of the data across all nodes in the Database. As a result of this, data is more easily available.
  • Data reliability is enhanced by Data Replication. Moreover, it allows multiple users and provides high performance.
  • To eliminate any data redundancy, Master Databases and slave Databases are updated with stale or incomplete data.
  • Because copies are made, there is a possibility that the data will be present where the transaction is being performed. This reduces data movement. It increases the speed of query execution which saves you and your company a lot of time.

Types of Database Replication

When it comes to Database Replication, there are generally the following 3 types of Data Replication possible from Databases:

1) Full Replication

Full Database Replication
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As the name suggests, Full Database Replication involves copying of everything, including existing, updated, and new data from the source to the target. This method is helpful if the records are hard deleted from the source regularly or if the source has not a suitable column for Key Based Incremental or Log Based. 

Few drawbacks that this method offers are listed below:

  • It requires more processing power.
  • Generates larger network loads than just copying only changed data.
  • Cost increases as the number of rows getting copied increases, irrespective of the tool you are using.   

2) Key-Based Incremental

Key-Based Incremental Data Replication is a method in which the data sources, like PostgreSQL, Oracle, Kafka, Snowflake, and SalesForce, etc. identify new and updated data using the column called the Replication Key. A key can be a timestamp, integer, or datestamp column that exists in the source table. 

When you are Replicating the table using Key-based Incremental Replication, the following things will happen:

  • During a replication job, PipelineWise stores the maximum value of the table’s replication key column. 
  • During the next replication job, the above-stated data sources will compare saved values from the previous job to the Replication key column values in the source. 
  • Any rows in the table with a Replication Key greater than or equal to the stored value are replicated. 
  • PipelineWise stores the new maximum value from the table’s Replication key column.

Following SQL query is related to the above-mentioned method:

SELECT replication_key_column,
      column_of_choice_1,
      column_of_choice_2,
      [...]
FROM schema.table
WHERE replication_key_column >= 'last_saved_maximum_value'

Key-Based Replication is a popular method, and it becomes very active, especially when Log-Based Replication is not working. 

Please note that Key-based incremental Replication does not detect deletes in the source.   

3) Log-Based Replication

Log-Based Replication is a method in which modifications are recorded to make necessary changes. For example, updates, inserts, and deletes using the Database’s binary log files. 

Log-Based Replication method is available only for MySQL, PostgreSQL, and MongoDB backend Databases that support Log Replication.

For more details, please refer to the following document

Steps to perform Database Replication

Data Replication Steps
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Here are a few steps that are required to perform Database Replication:

  • Step 1: The first step is to narrow down the data source and the target system.
  • Step 2: Now, choose tables and columns that need to be copied from the source.
  • Step 3: You need to identify how frequently updates are required to be made.
  • Step 4: Now, select a Data Replication technique (full, partial, or log-based).
  • Step 5: Next, write custom code or use Data Replication software to perform the process.
  • Step 6: Lastly, closely monitor how the data extracts, filters, transforms, and loads to ensure quality.

Importance of Database Replication

Data Replication Throughout the World
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Database Replication is important because of the following reasons:

  • Data Reliability and Availability: Because of Data Replication, the availability of data becomes easy. As mentioned in the introduction, it provides a vital role when a server crashes under extraordinary conditions. So it provides the backup of the Database and hence saves the day as data is available in other locations.
  • Disaster Recovery: In the case of Server loss, Data Replication provides disaster management as it gives a copy of the latest data changes. 
  • Server Performance: When data is being processed and run on multiple Servers instead of one, it makes data access very quick. Moreover, when all data read operations directs to a replica, admins can reduce processing cycles on the primary Server for more resource-exhaustive write operations.
  • Better Network Performance: Keeping copies of the same data in various locations can reduce data access latency as you can retrieve the required data from the location where the transaction executes. For example, users in Asian or European countries may face latency issues when accessing data from Australian data centers. However, placing a Replica of this data somewhere close to the user can enhance access times while balancing the load on the network.
  • Enhanced Test System Performance: Replication simplifies the distribution and synchronization of data for test systems that mandate quick accessibility for faster decision-making.

Database Replication Challenges

Although Data Replication adds much value to your work and your company, it still comes along with the following challenges:

  • Higher Costs: When you have to maintain multiple copies of the same data over various locations, it results in higher costs as it requires more hardware and processing power to perform basic functionalities on the data. 
  • Time Constraints: You need time to perform Data Replications and experts to perform the job and make sure that Data Replication is done properly. 
  • Bandwidth: To preserve consistency across Data Replicas, you need better bandwidth as it can result in increased traffic. 
  • Inconsistent Data: It could be a tricky point when the environment is distributed because copying of data from different locations at different intervals can lead to some data not syncing with the rest of the data. So, data admins must make sure that data is updated. 
  • Data Replication Tools Availability: There are multiple Data Replication tools available in the market to make your life easy.

Database Replication Tools

There are numerous tools available in the market that can efficiently carry out your Data Replication work. Following tools are the most popular in the current business markets:

1) Hevo Data

Hevo Data Logo
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Hevo Data, a No-code Data Pipeline, helps to transfer data from 100+ sources to your desired Data Warehouse/ Destination and visualize it in a BI tool. Hevo is fully managed and completely automates the process of not only loading data from your desired source but also enriching the data and transforming it into an analysis-ready form without having to write a single line of code. Its fault-tolerant architecture ensures that the data is handled in a secure, consistent manner with zero data loss.

2) Rubrik

Rubrik Logo
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Rubrik is a Cloud-based Data Management and backup tool that provides instant backup, archive, restore, analysis, and copy management of data. It offers simplified backup and integration with modern data center technologies. With an easy-to-use interface, you can easily host and authorize any user group.

3) Carbonite

Carbonite Tool Logo
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It provides both Data replication and Disaster Recovery options in a combined pack. It is one of the few tools that can handle duplication of physical as well as virtual environments. Carbonite works best in a scenario where continuous Data Replication is required without any time constraints.

4) SharePlex

SharePlex Logo
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SharePlex is one of the few tools that implement real-time Data Replication. The tool supports many types of Databases and is highly customizable. Thanks to its message queuing mechanism, it provides fast data transfer and high scalability. SharePlex is best for the process involving Heterogeneous Replication among Databases. If you want to expand from on-base replication to cloud, this tool will be perfect for you.

Conclusion

In this blog, you have learned about Database Replication, types of Database replication, how to achieve it, and its importance. Moreover, it explained the difference between Data Replication and Mirroring and also listed down the most popular tools for Data Replication. However, if you are looking for an easy solution, then try Hevo.

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