🔥 The DB Grill 🔥

Oh, fantastic. Another deep dive into how a game-changing feature will solve the fundamental problem of the query planner occasionally having the statistical awareness of a squirrel in traffic. This was a truly comforting read.

It's so reassuring to know that instead of a predictably terrible nested loop join, I can now have a query that sometimes decides to be terrible, based on a black box crossover point that was ported over from Oracle. That's a relief. Bringing in concepts from a famously simple, open, and low-cost database is always a winning strategy for a startup.

I especially love the part where you manually ANALYZE the table to update the statistics, and the planner's estimate gets even worse.

The reason is that even with a freshly analyzed table, the optimizer’s estimate is worse than before: it predicts fewer rows (rows=23) when there are actually more (rows=75).

This is my favorite kind of feature. The one where doing the textbook-correct thing actively makes the magic, intelligent system less intelligent. It's just so... predictable. It really brings back fond memories of that one 'simple' migration to a NoSQL document store that promised schema-on-read, which in practice just meant undefined on-call at 3 AM. Good times.

It’s wonderful that this feature "doesn’t try to find the absolute best plan" but instead focuses on "avoiding the worst plans." That’s the kind of fighting spirit and commitment to aggressive mediocrity I look for in my critical infrastructure. We're not aiming for success, we're just trying to fail slightly less catastrophically. It's an inspiring engineering philosophy.

I can already picture the incident ticket.

• Problem: The /api/v1/critical-thing endpoint is timing out.
• Initial Investigation: The query plan looks... fine? Oh, wait, it just changed. And again. And now it’s back.
• Root Cause: The adaptive planner is having an existential crisis because a cron job updated three rows, pushing it just past the apg_adaptive_join_crossover_multiplier threshold we definitely remembered to tune. The plan is now "good enough" to time out gracefully instead of instantly.

This whole thing just replaces an old, familiar problem with a new, excitingly unpredictable one. Before, the plan was just bad. Now, the plan is a Schrödinger's Cat of performance, and you can only find out if it's dead by opening the production box.

Anyway, this was a fantastic read. Truly. It’s given me a whole new set of failure modes to have anxiety dreams about. I'll be sure to never read this blog again, for my own health.

Cheers.