Database Indexing Mistakes That Are Quietly Killing Your App's Performance
Indexing is one of those topics every developer has heard of, most have used, and surprisingly few have actually reasoned through carefully. It's easy to add an index and move on — it's much harder to know whether that index is actually helping, or just adding write overhead while your slow query is still slow for a completely different reason. Here are the indexing mistakes that show up again…
The article "Database Indexing Mistakes That Are Quietly Killing Your App's Performance" outlines five common indexing mistakes developers often make that can negatively impact application performance. The first mistake is indexing every column "just in case," which overlooks the fact that every index has a cost on every write operation, potentially turning simple inserts into multiple write operations.
The second mistake is ignoring column order in composite indexes, as the order matters for efficient use of the index. The third mistake is not indexing foreign keys, which can lead to full table scans for related queries. The fourth mistake is trusting an index without checking if it's actually being used, as certain query patterns can prevent index usage.
Lastly, the article warns against over-indexing for queries that should be cached, as indexing only helps find rows faster, not perform heavy aggregation work. The article concludes with a practical way to audit existing indexes by listing all indexes and their sizes.
Brief written by urgent.news from Dev.to's own syndicated text. Machine-written — may contain errors; check the original before relying on it.
