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Comment by p0w3n3d | Hacker News Reader

Postgres. Only postgres.

Why? Because once your app gets more than _n_ users you will run into scaling problems and then you end up with huge tech debt

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But n can be so big that it you never run into it. My company has a read-heavy SQLite-backed service that serves roughly 150,000 daily users with p99.9 at about 5 milliseconds. We did some rough projection and determined we could reach the total addressable market of our product in the US without even approaching having a problem.

How can your company guarantee p99.9 if there is only one instance? Is there any log shipping/duplication etc? Is consistency maintained on one server fault?

p99.9 referring to latency. However, we also do a weekly test of how quickly we recover from a catastrophic crash, which is roughly about 6 minutes (which is the amount of time it takes for the autoscaling group to spin up a new host, Litestream to restore the database from s3, and the server to start up again).

Honestly, 99.9% uptime is pretty generous - we can fit in quite a few catastrophes per year and still have 99.9% uptime. In the 2 years this service has been running, we've had 100% uptime via zero-downtime deployments, anyway.

In terms of monitoring, traces and error logs are shipped to our observability solution, yes.

> Why? Because once your app gets more than _n_ users you will run into scaling problems and then you end up with huge tech debt

Anecdote: the sqlite forum runs on a single sqlite db and has well over 1500 users. Similarly, the sqlite source site is heavily visited by thousands of folks and actively used in write mode by its developers. It sibling project, the Fossil SCM, also runs entirely from a single sqlite db.

sqlite db forum stats: <https://sqlite.org/forum/reports>

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