Sequence Number

Generating unique ID seems to be a simple task, but it is not in a high-load distributed systems!

This topic consists of:

• Understanding the requirements and why it is a complicated task
• Possible solutions:
  • Multi-master replication
  • Universally unique identifier (UUID)
  • Ticket server
  • Twitter SNOWFLAKE approach (seems to be the best one!)
• Details:
  • Timestamp
  • Sequence number
• Other issues
  • Clock synchronization
  • Section length tuning
  • High availability

These items are disclosed in a very interesting Chapter 7 of the book:

Earlier the book club of our company has studied excellent book:

Martin Kleppmann - Designing Data-Intensive Applications

This is the best book I have read about building complex scalable software systems. 💪

As usually I prepared an overview and mind-map.

Chapter 9 tells about Consistency and Consensus in distributed systems. It covers the following topics:

• What is consistency and eventual consistency
• Linearizability. Why it is needed. Difference from Serializability. How to implement Linearizability. The cost of Linearizability. CAP theorem.
• Ordering Guarantees. What is ordering and causality. It’s relation to Linearizability. Sequence Number Ordering and how to implement it. Total Order Broadcast and how to implement it.
• Distributed Transactions and Consensus. Why we need Consensus and Distributed Transactions. How to implement them, related problems and software that helps.

Summary: