System Design Basics - Database Replication & Sharding

Learn how to handle massive datasets and high traffic loads with database replication and sharding.

Hello guys, database replication and sharding are two important topics for system design interview as both are very important for scalability and avaibility of your application.

Before we jump into Database replication and Database sharding, let me tell you a story where a solution involving database replication built my reputation in new team and landed me promotion next year.

I remember working for a big financial project where our master database was in UK but a large number of clients were in Asia like Japan, Australia, China, India, and HK.

One of big issue we face was poor performance when system startups and for some reason if you have to restart app during trading open or close session, you will miss the entire session.

Obviously the issue was that database was too far away and the network pipes we had were not big enough (bandwidth), considering everything else going on that pipe from emails to all kind of data transfers.

The first thing I did after joining the team was to propose a new architecture where we will replicate the database to multiple regional centers like Japan, HongKong, Australia, India etc and creating local caches so that even if database is not available our system can function.

Obviously this kind of issues comes when a system is not designed for global use. In most cases, a successful app working in EMEA and US are just deployed to APAC, hoping everything will just work magically.

That simple act not only built my reputation but also landed me good bonus and promotion next year. So you can think how important it is to know about different System design concepts and we will see another one today.

If you are new here, In the past, I have talked about common system design questions like Rate Limiter, Database Scaling, API Gateway vs Load Balancer and Horizontal vs Vertical Scaling, Forward proxy vs reverse proxy as well common System Design problems and concepts like Single Point Failure, and in this article we will talk about Database replication and Database Sharding, two important topics from scalability and system avaibility point of view.

For this article, I have teamed up with Hayk and we'll dive into the fundamental concepts of database scaling and Sharding, and provide practical insights to help you make informed decisions about your data architecture.

By the way, if you are preparing for System design interviews and want to learn System Design in depth then you can also checkout sites like ByteByteGo, Design Guru, Exponent, Educative, Codemia.io, and Udemy which have many great System design courses

Database Replication & Sharding Explained

When designing large-scale systems, one of the biggest challenges is ensuring the system remains responsive even when handling massive volumes of data and concurrent user requests.

In such scenarios, the database often is the primary bottleneck.