Step 3: Consistency vs Availability

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Overview

This step covers the fundamental trade-offs between consistency and availability in distributed systems, including the CAP theorem, consistency levels, isolation levels, and decision frameworks for choosing the right balance for your system.

Topics Covered

1. Data Consistency & Its Levels

  • Strong vs eventual consistency
  • Consistency models and guarantees
  • Real-world examples and trade-offs
  • Implementation patterns

2. Isolation & Its Levels

  • ACID isolation levels
  • Concurrency control
  • Read phenomena and anomalies
  • Transaction isolation strategies

3. CAP Theorem

  • Consistency, Availability, Partition tolerance
  • CAP theorem implications
  • Real-world system examples
  • Decision frameworks

4. Where to Give Priority

  • When to prioritize consistency
  • When to prioritize availability
  • Hybrid approaches
  • System design decision framework

Quick Navigation

TopicFileKey Concepts
Data Consistencydata-consistency-levels.mdStrong, eventual, causal, session consistency
Isolation Levelsisolation-levels.mdRead uncommitted, committed, repeatable, serializable
CAP Theoremcap-theorem.mdConsistency, Availability, Partition tolerance
Priority Frameworkpriority-decision-framework.mdDecision making, trade-offs, real-world examples

Learning Path

  1. Start Here: Understand consistency levels and models
  2. Isolation: Learn transaction isolation and concurrency
  3. CAP Theorem: Grasp the fundamental trade-offs
  4. Decision Making: Learn when to prioritize what

Key Takeaways

  • Consistency Models: Understand strong vs eventual consistency
  • CAP Theorem: Can't have all three (C, A, P) simultaneously
  • Trade-offs: Every system makes trade-offs between consistency and availability
  • Decision Framework: Choose based on use case and requirements
  • Step 2: Database replication relates to consistency
  • Step 6: Consistent hashing affects consistency
  • Step 8: Microservices architecture impacts consistency
  • Step 11: System design trade-offs

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Next Step: Step 4: Caching →

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