Where database blog posts get flame-broiled to perfection
Ah, another masterpiece from the content marketing machine. I was just thinking my morning coffee needed a little more... corporate wishful thinking. And here we are, celebrating the "enthusiasm" for UUIDv7. Enthusiasm. That's what we're calling the collective sigh of relief from engineers who've been screaming about UUIDv4's index fragmentation for the better part of a decade.
Let's dive into this "demo," shall we? It’s all so clean and tidy here in the "lab."
-- reset (you are in a lab) ! pkill -f "postgres: .* COPY"
Right out of the gate, we're starting with a pkill. How... nostalgic. It reminds me of the official "fix" for the staging environment every Tuesday morning after the weekend batch jobs left it in a smoldering heap. It’s comforting to see some traditions never die. So we’re starting with the assumption that the environment is already broken. Sounds about right.
And the benchmark itself? A single, glorious COPY job streaming 10 million rows into a freshly created table with no other load on the system. It's the database equivalent of testing a car's top speed by dropping it out of a plane. Sure, the numbers look great, but it has absolutely no bearing on what happens when you have to, you know, drive it in traffic.
Look at these UUIDv7 results! "Consistently high throughput, with brief dips likely due to vacuum, background I/O or checkpoints..." Brief dips. That’s a cute way to describe those terrifying moments where the insert rate plummets by 90% and you're not sure if it's ever coming back. I remember those "brief dips" from the all-hands demo for "Project Velocity." They weren't so brief when the VP of Sales was watching the dashboard flatline, were they? We were told those were transient telemetry anomalies. Looks like they've been promoted to a feature.
And the conclusion? UUIDv7 delivers "fast and predictable bulk load performance." Predictable, yes. Predictably stalling every 30-40 seconds.
Now for the pièce de résistance: the UUIDv4 run. The WAL overhead spikes, peaking at 19 times the input data. Nineteen times. I feel a strange sense of vindication seeing that number in print. I remember sitting in a planning meeting, waving a white paper about B-Tree fragmentation, and being told that developer velocity was more important than "arcane storage concerns." Well, here it is. The bill for that velocity, payable in disk I/O and frantic calls to the storage vendor. This isn't a surprise; it's a debt coming due.
But the best part, the absolute chef's kiss of this entire article, comes right at the end. After spending paragraphs extolling the virtues of sequential UUIDv7, we get this little gem:
However, before you rush to standardize on UUIDv7, there’s one critical caveat for high-concurrency workloads: the last B+Tree page is a hotspot...
Oh, is it now? You mean the thing that everyone with a basic understanding of database indexes has known for twenty years is suddenly a critical caveat? You're telling me this revolutionary new feature, the one that’s supposed to solve all our problems, is great... as long as only one person is using it at a time? This has the same energy as the engineering director who told us our new, "infinitely scalable" message queue was production-ready, but we shouldn't put more than a thousand messages a minute through it.
And the solution? This absolute monstrosity: (pg_backend_pid()%8) * interval '1 year'.
Let me translate this for the people in the back. To make our shiny new feature not fall over under the slightest hint of real-world load, we have to bolt on this... thing. A hacky, non-obvious incantation using the internal process ID and a modulo operator to manually shard our inserts across... time itself? It's the engineering equivalent of realizing your car only has a gas pedal and no steering wheel, so you solve it by having four of your friends lift and turn it at every intersection. It's not a solution; it's an admission of failure.
This is classic. It's the same playbook:
Anyway, this has been a wonderful trip down a very bitter memory lane. You've perfectly illustrated not just a performance comparison, but the entire engineering culture that leads to these kinds of "solutions."
Thanks for the write-up. I will now cheerfully promise to never read this blog again.