Yashotantra Academy logo
← System Design theorytheory 0/5 · 0%
level 1
Curious · 0 XP
streak
0d
perfect
0
badges
0

100 XP to Apprentice

Data Architecture · medium

5. Replication, Sharding, and Database Choices

Scaling data reads and writes without hiding consistency trade-offs.

1 min read3 questionsup to 50 XPtopic 5/5

Read in another language

AI translates the explanation and quiz text while preserving code and answer scoring.

Replication keeps multiple copies of data. A primary-replica topology can scale reads and provide failover, but replicas may lag. Sharding partitions rows across machines using a shard key; a good key distributes traffic evenly and supports common query paths.

Choose storage by access patterns: relational databases provide transactions and joins, document stores fit flexible aggregates, key-value stores favor predictable lookups, and search indexes optimize text retrieval. A system design answer should explain the workload before naming a database.

How to study this topic

  1. 1. Read the explanation once end to end, skipping the code.
  2. 2. Re-read the code snippets and say out loud what each line does.
  3. 3. Answer the quiz without scrolling back — that is the real check.
  4. 4. Read every explanation, even for the answers you got right.

Scoring

  • · Up to 30 XP from quiz accuracy.
  • · +15 XP for a perfect first attempt.
  • · +5 XP while a 3-day streak is running.
  • · 75% or higher marks the topic complete.

Check your understanding

  1. 1. What is a common drawback of reading from a replica immediately after a write?

  2. 2. What makes a good shard key?

  3. 3. Which workload is a relational database especially suited to?

Badges

First light
Pass your first topic
Sharp shooter
3 perfect first-try quizzes
On a roll
Study 3 days in a row
Week warrior
Study 7 days in a row
Grinder
Earn 500 XP
Deep diver
Earn 1500 XP