TOPIC #192Intermediate 10 min read

Read-Heavy vs Write-Heavy Architecture Trade-Offs

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Key takeawayCore Architecture Summary

Architect for divergent workload profiles: Deep comparison of storage engines (B+ Trees vs LSM Trees), CQRS read denormalization vs write-buffering queues, and fan-out-on-write vs fan-out-on-read.

Key Glossary Concepts in this TopicAll Glossary Terms

01.Identifying the Workload Profile (The Read:Write Ratio)

One of the most consequential decisions in distributed system design is identifying whether an application's bottleneck is Read Throughput or Write Throughput:

1. Read-Heavy Workloads (e.g., Twitter, Instagram, Wikipedia, YouTube, eCommerce)

  • Ratio: 100:1 to 1,000:1 (reads dominate 99\% of traffic).
  • Core Challenge: Minimizing query latency (target < 10 ms p99) and offloading primary database engines under massive concurrent user queries.
  • Architectural Goal: Maximize cache hit ratios, pre-compute data at write time (Fan-out-on-write), maintain denormalized materialized views, and utilize multiple read replicas.

2. Write-Heavy Workloads (e.g., Uber GPS Tracking, IoT Telemetry, Financial Ledgers, Ad Impressions)

  • Ratio: 1:1 to 1:100 (90\%+ of operations are new insertions or updates).
  • Core Challenge: Ingesting millions of events per second without disk I/O bottlenecks, lock contention, or transaction serialization delays.
  • Architectural Goal: Eliminate random disk seeks, buffer writes in memory, leverage append-only commit logs, minimize secondary indexing, and defer query computations to read time.

Read-Heavy vs Write-Heavy Architectural Topologies ⚖️

PRO Architecture Blueprint

Read-Heavy vs Write-Heavy Architectural Topologies ⚖️

B+ Tree caching and denormalization for fast retrieval vs LSM-Tree partitioned streaming for high-velocity append ingestion.

Read-Heavy vs Write-Heavy Architectural Topologies ⚖️
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