#backend

The queue, the cache, the search index, the vector store, the job scheduler and the analytics table for a product with 40,000 daily users all live in one Postgres 18 instance. That is not a compromise. It is the design. Here is what each piece looks like, what it costs, and the three specific signals that would make me move one of them out.

A model provider had a bad Tuesday and our summarisation feature spent four hours returning empty strings to customers, because nothing between the API and the user knew what to do with a 529. The feature now has a kill switch, a fallback, a budget, and a canary. Those four things are the difference between an LLM feature and an LLM demo.

Node 24 ships TypeScript, a test runner, fetch, a permission model and a single-file executable builder. Bun is faster at almost everything and now has a company with deep pockets behind it. Deno has the cleanest security story. I run all three in production and the answer to 'which one' is different for each of my four services, for reasons that have nothing to do with benchmarks.

Python 3.14 made the no-GIL build officially supported and the single-thread penalty dropped from 40 percent to single digits. I moved a CPU heavy ingestion service across. The 3x speedup on the hot path was real. So were the three bugs that only exist without the lock, and none of them showed up in tests.