Scalability

Scalability and Load Balancing Concepts

Explains vertical vs horizontal scaling and how load balancers distribute traffic across servers, including round robin and least connections.

Scalability Fundamentals

Core concepts behind building systems that handle growing load gracefully, including scaling dimensions, bottleneck identification, and the diminishing returns…

Difference Between SQL and NoSQL Databases

SQL databases are relational, store data in structured tables with a fixed schema, and use SQL for querying; NoSQL databases are non-relational, store data in…

What is Database Sharding?

Database sharding is a horizontal partitioning technique that splits a large dataset across multiple independent database servers (shards), where each shard ho…

What is Connection Pooling?

Connection pooling is a technique where a fixed set of pre-established database connections is reused across multiple requests instead of opening and closing a…

What is a Column-Family Database Model?

A column-family database groups related columns into named families and stores each row's data physically by column family rather than by row, so queries touch…

Wide-Column Store vs Relational Database: What is the Difference?

A wide-column store lets each row hold millions of dynamically named, sparse columns grouped by family and distributed by row key across many nodes, while a re…

How Do You Choose a Sharding Key?

A good sharding key is a column with high cardinality and an even, predictable value distribution that matches your query patterns, so writes and reads spread…

What is Range-Based Sharding?

Range-based sharding assigns rows to shards based on contiguous ranges of the shard key's value, so each shard owns a specific, ordered slice such as user IDs…

What is Hash-Based Sharding?

Hash-based sharding applies a hash function to the shard key and uses the result (typically modulo the shard count) to assign each row to a shard, which spread…

What is Consistent Hashing and Why Do Databases Use It?

Consistent hashing maps both shard keys and shard servers onto the same circular hash space, so each key is owned by the next server found clockwise on the rin…

What Challenges Arise When Resharding and Rebalancing a Database?

Resharding, moving data to a new number of shards or a better key layout, is challenging because it must move large volumes of live data without downtime, keep…

What Are TimescaleDB Hypertables and How Do They Work?

A TimescaleDB hypertable is a PostgreSQL table that is automatically partitioned behind the scenes into many smaller physical tables called chunks, typically s…

What is Eventual Consistency in Databases?

Eventual consistency is a consistency model where, after writes stop arriving, all replicas of a piece of data are guaranteed to converge to the same value eve…

Strong Consistency vs Eventual Consistency: What is the Difference?

Strong consistency guarantees that any read immediately after a write returns that write's value everywhere, while eventual consistency allows reads to briefly…

What is Database Connection Multiplexing?

Database connection multiplexing is the technique of sharing a small pool of real database connections across a much larger number of client requests, typicall…

How Do You Approach Database Capacity Planning?

Database capacity planning means forecasting future storage, throughput, and connection needs from current growth trends and peak-load patterns, then provision…

How Would You Design a Concurrent Hash Map?

A concurrent hash map achieves thread-safe reads and writes at scale by splitting the table into independently lockable segments (or per-bucket locks) instead…

What is Consistent Hashing and Why is it Used?

Consistent hashing maps both keys and servers onto the same circular hash ring so that when a server is added or removed, only the keys between it and its neig…

What is a Load Balancer in Networking?

A load balancer is a device or service that sits in front of a pool of backend servers and distributes incoming client requests across them using a chosen algo…

What is a Load Balancer Algorithm?

A load balancer algorithm is the rule a load balancer uses to decide which backend server receives each incoming request — common examples include round robin,…

Round Robin vs Least Connections Load Balancing

Round robin distributes requests to backend servers in a fixed rotating order regardless of current load, while least connections sends each new request to whi…

What is Load Balancing?

Load balancing is the practice of distributing incoming network traffic across multiple backend servers so no single server is overwhelmed, improving availabil…

What is Caching in System Design?

Caching is storing copies of frequently accessed data in a fast, temporary layer so future requests are served from it instead of the slower original source, r…

Horizontal vs Vertical Scaling

Vertical scaling (scaling up) means adding more power — CPU, RAM or disk — to a single machine, while horizontal scaling (scaling out) means adding more machin…

What is a CDN (Content Delivery Network)?

A CDN (Content Delivery Network) is a geographically distributed network of edge servers that cache and serve content from a location close to each user, reduc…