Day 7Level 1 — Core Mental Models
Consistency Models: Strong, Eventual, Causal, Read-Your-Writes
Learn: 45 minMap: 30 minDesign: 60 min
Core Concepts (5)
- 1.Strong consistency: linearizability — single copy illusion
- 2.Eventual: all replicas converge, but when? conflicts possible
- 3.Causal: if A causes B, all nodes see A before B
- 4.Read-your-writes: session guarantee — your writes visible to you
- 5.The consistency spectrum is a cost/latency/availability trade-off
Map to Your Experience
Your system has a user profile service. What consistency model does it need? What happens if you relax from strong to causal? What breaks?
Design Brief: Consistency Model Selection for a Feature
Requirements
- •Identify feature and its consistency needs
- •Specify exact consistency model required
- •Analyze impact of weakening by one level
- •Document conflict resolution if eventual
Constraints
- •Use real feature from your system
- •Be specific about anomaly scenarios
Must Cover
model-selectionjustificationweakening-analysisconflict-resolution
Trade-off Axis
consistency strength vs latency/availability/cost
Referenced Patterns
Competencies Advanced
data state → L3reliability ops → L2
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