Design a key-value store in HLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a key-value store?

A key-value store is a simple database that stores data as pairs of keys and values. Each key is unique and is used to retrieve its associated value quickly.

intermediate

Why is partitioning important in a key-value store?

Partitioning splits data across multiple servers or storage units. It helps the system handle more data and requests by distributing the load, making the store scalable and faster.

advanced

What is consistent hashing and why is it used?

Consistent hashing is a technique to distribute keys evenly across servers. It minimizes data movement when servers are added or removed, helping maintain balance and availability.

intermediate

Explain the role of replication in a key-value store.

Replication means copying data to multiple servers. It improves reliability and availability, so if one server fails, data can still be accessed from others.

advanced

What is eventual consistency in distributed key-value stores?

Eventual consistency means that after some time, all copies of data will become the same. It allows faster writes but may show old data temporarily.

What does a key-value store primarily use to retrieve data?

A Unique keys

B Indexes

C SQL queries

D File paths

Key-value stores use unique keys to quickly find the associated values.

Which technique helps distribute keys evenly across servers in a key-value store?

A Caching

B Consistent hashing

C Replication

D Sharding by range

Consistent hashing evenly distributes keys and reduces data movement when servers change.

What is the main benefit of replication in a key-value store?

A Reduces storage needs

B Speeds up writes

C Improves fault tolerance

D Simplifies data model

Replication copies data to multiple servers to keep data safe if one server fails.

Which consistency model allows temporary differences in data copies but guarantees eventual agreement?

A Eventual consistency

B Strong consistency

C Immediate consistency

D Read-your-writes consistency

Eventual consistency allows temporary differences but ensures all copies match eventually.

Partitioning in a key-value store is mainly used to:

A Backup data

B Encrypt data

C Compress values

D Distribute data across servers

Partitioning splits data to spread load and improve scalability.

Describe the main components and flow of a key-value store system.

Think about how data is stored, found, and kept safe.

Explain how consistent hashing helps in scaling a key-value store.

Imagine how to keep data balanced when servers join or leave.