Recently, I went deep on SQL performance while investigating database load in Postgres, and it changed how I debug DB issues.
The shift wasn't writing "clever" SQL. It was learning how the database actually executes queries.
I used to tweak queries and hope for improvement. Now, when I see elevated DB load or timeouts, I start by asking why the database is doing the work it's doing.
A few things that changed my approach
- SQL performance isn't about the query text, it's about the execution plan
- If you're not reading the plan, you're mostly guessing
- Execution plans and indexes are diagnostic tools, not magic fixes
- Small schema and data distribution decisions get very expensive at scale
- In Postgres, ANALYZE and VACUUM directly affect plan quality and performance stability
If you're not reading the plan, you're mostly guessing.
Treating performance issues as system behavior — rather than trial-and-error — has made debugging more predictable.