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Summary - Replication and sharding

Shard a users table by shard key.

Summary - Replication and sharding

Replication copies data (publication/subscription), sharding splits it (PARTITION BY HASH/RANGE). Master writes, slaves read. Synchronous is consistent, asynchronous is fast.

-- CREATE PUBLICATION -> CREATE SUBSCRIPTION
-- PARTITION BY HASH / RANGE

Replication copies, sharding splits.

Practice Summary - Replication and sharding

Summary task: shard the users table with PARTITION BY HASH (user_id).

Starter code

query.sql
-- summary sharding
CREATE TABLE users (user_id INT, name TEXT)

Sample solution

query.sql
CREATE TABLE users (user_id INT, name TEXT) PARTITION BY HASH (user_id);

Expected output

CREATE TABLE

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Replication publication

Question 
CREATE PUBLICATION pub_users FOR TABLE ____
Answer 
CREATE PUBLICATION pub_users FOR TABLE users

Explanation: Changes to the users table added to the publication are copied to subscribers.

2 How does sharding split data?

  • Vertically
  • By type
  • Horizontally Correct answer
  • By column

Explanation: Sharding splits data horizontally.

3 Summary - Replication and sharding: match the terms

Term Meaning
replication copy
sharding split
master master
sync sync

All lessons in Expert

1 Database design

  1. ER model
  2. Cardinality
  3. Surrogate keys
  4. Natural keys
  5. Denormalization
  6. Summary - Design

2 Index tuning

  1. B-tree structure
  2. Covering index
  3. Partial index
  4. Index selectivity
  5. Index maintenance
  6. Summary - Index tuning

3 Query optimizer

  1. What is an optimizer?
  2. Statistics
  3. Cost model
  4. Join strategies
  5. Plan cache
  6. Summary - Optimizer

4 Project: Performance tuning

  1. Scenario design
  2. Reading plans
  3. Adding indexes
  4. Rewriting queries
  5. Comparing results

5 Replication and sharding

  1. What is replication?
  2. Master-slave
  3. Sync vs async
  4. What is sharding?
  5. Shard key
  6. Summary - Replication and sharding

6 Distributed and big data

  1. Distributed queries
  2. MPP
  3. Columnar storage
  4. SQL on Hadoop
  5. SQL vs NoSQL
  6. Summary - Distributed and big data

7 Security and backup

  1. SQL injection
  2. Parameterised queries
  3. Authorisation
  4. Backup
  5. Recovery
  6. Summary - Security and backup

8 Expert final

  1. Design challenge
  2. Optimization challenge
  3. Security challenge
  4. Backup challenge