Engineering Blog
Deep dives into unique identifiers, database performance, and the real-world trade-offs of building distributed systems. From UUID internals to database migrations, benchmarks, and production incidents, we explore the engineering decisions, implementation details, and lessons learned along the way.
Latest Articles
Engineering deep dives on UUID performance, migrations, and production lessons.
Latest
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2026-09-15 — Why Your AI Keeps Hallucinating Fake UUIDs And How to Stop It
LLMs are token predictors, not CSPRNGs: why they generate invalid duplicates and how to fix it with tool calling.
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2026-08-16 — Why Switch From Auto-Increment IDs to UUIDs (and What Might Break)
Migration risks: foreign keys, ORMs, sorting, and what breaks when you switch.
Articles
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The Great Index Fragmentation Debate: Do UUIDs Really Kill Performance?
Benchmarks: does random UUID v4 actually kill Postgres/MySQL performance?
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5 Real-World Bugs Caused by Bad UUID Implementations
Production bugs: case sensitivity, Math.random(), and parsing failures.
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Benchmark: UUID vs BIGINT Insert/Query Speed
1M row benchmark: insert, select, and join speed for UUID vs BIGINT.
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How Big Tech Generates Unique IDs at Scale (Twitter Snowflake, Instagram)
Snowflake, Instagram ID, ULID — how big tech avoids UUID bottlenecks.
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Migrating a Legacy Database From Integer IDs to UUIDs: A Case Study
Step-by-step migration: backfill, dual-write, and zero-downtime switch.
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What's New in RFC 9562: UUID v6, v7, and v8 Explained
RFC 9562 adds v6, v7, v8 — sortable timestamps and custom UUIDs.
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NanoID: Why Some Developers Are Ditching UUIDs for Shorter IDs
Why NanoID's 21-char IDs beat 36-char UUIDs for URLs and UX.
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Common UUID Mistakes Developers Make (and How to Avoid Them)
Top mistakes: storing as varchar, using v1, and insecure random.
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UUID Collision Stories: When Astronomically Unlikely Still Happens
Real collision stories: bad RNG, birthday paradox, and lessons.
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Using Prefixes For Human Readable UUIDs
Stripe-style prefixed IDs: user_123, order_xxx for readable UUIDs.