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Screenshot of alexsci.com: UUIDv7: Timestamps aren’t time-ordered and other oddities

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UUIDv7: Timestamps aren’t time-ordered and other oddities

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Blog post arguing that UUIDv7 does not reliably provide monotonic ordering, accurate creation timestamps, or unguessability, examining RFC 9562 and implementations like Python's.

What HN thinks

A room full of DBAs gently explaining that nobody asked UUIDv7 to tell the time.

Article misses UUIDv7's real purpose
Most commenters say UUIDv7 exists for index locality and fewer B-tree page splits, not for exact timestamps or strict monotonicity, so the article argues against claims nobody made.
Just use serial integer keys
Several argue integer primary keys are smaller and faster, with a separate random UUIDv4 for public-facing IDs; others counter that distributed systems need coordination-free IDs.
Know the limits before relying on it
Some agree the caveats matter: timestamps leak creation time, ordering is only approximate across machines and commits, and implementations vary.

Consensus: Most agree UUIDv7 is a pragmatic fix for random-key insert performance and should not be treated as an exact clock, a strict ordering, or a secret.

Recommended in the comments

uuid-utils ↗ (library): Recommended over the uuid7 PyPI package, which implements an incompatible draft format.
CUID2 (library): Suggested when you need unguessable IDs.
ULID ↗ (other): Named as an older alternative with similar properties and possibly better encoding.
Snowflake ID ↗ (other): Mentioned as an alternative with properties similar to UUIDv7.

Summarised by Claude from the comment thread 2 days ago.

Points: 150
Comments: 121
Best rank: #3
Posted: 2026-10-23 by ibobev
Category: Programming

uuidv7 uuid rfc-9562 python distributed-systems clock-skew postgresql

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