Comment by sgarland
Comment by sgarland a day ago
> 200ms for DB queries
No. Just no. There’s an entire generation of devs at this point who are convinced that a DB is something you throw JSON into, use UUIDs for everything, add indices when things are slower than you expected, and then upsize the DB when that doesn’t fix it.
RAM access on modern hardware has a latency of something like 10 nanoseconds. NVMe reads vary based on queue depth and block size, but sub-msec is easily attainable. Even if your disks are actually a SAN, you should still see 1-2 msec. The rest is up to the DB.
All that to say, a small point query on a well-designed schema should easily execute in sub-msec times if the pages are in the DB’s buffer pool. Even one with a small number of joins shouldn’t take more than 1-2 msec. If this is not the case for you, your schema, query, or DB parameters are sub-optimal, or you’re doing some kind of large aggregation query.
I took a query from 70 to 40 msec today just by rewriting it. Zero additional indexing or tuning, just unrolling several unnecessary nested subqueries, and adding a more selective predicate. I have no doubt that it could get into the single digits if better indexing was applied.
I beg of devs, please take the time to learn SQL, to read EXPLAIN plans, and to measure performance. Don’t accept 200 msec queries as “good enough” because you’re meeting your SLOs. They can be so much faster.
Beg all you want. They're still going to dump JSON strings (not even jsonb) and UUIDs in them anyway, because, "Move fast and break things."
I lament along with you.