Hey everyone, I ran into a nasty performance issue the other day and thought I’d share what I learned. It all started when I noticed some of our biggest queries were crawling—turns out we were missing some crucial indexes. Without them, the database was forced to scan entire tables, which was brutal on performance.
On the flip side, I’ve also seen teams go overboard with indexes. It might seem like more is better, but piling on too many—or indexes that are wider than necessary—actually drags down write operations. Every INSERT or UPDATE has to touch those indexes, so you end up trading one problem for another.
One subtle trap I stumbled into was composite indexes with columns in the wrong order. I thought I’d covered all my bases, but because I didn’t respect the leftmost-prefix rule, some queries still fell back to full scans. And don’t even get me started on index fragmentation. Without regular rebuilding or reorganization, what started as a speed boost can morph into a liability.
These days I always start with an EXPLAIN plan and keep an eye on the slow query log. That way I can spot which filters and joins aren’t being served by an index and add targeted ones where they’ll actually help. It’s not a set‑and‑forget deal—I schedule periodic maintenance to rebuild indexes so they stay efficient. In the end, indexes should be your helpers, not a headache. Keep them lean, keep them tuned, and they’ll keep your queries flying.
