21/06/2026
After 19 years of SQL Server in production, here are the lessons I wish someone had told me earlier โ most of them learned by breaking things first. ๐
1๏ธโฃ Index early, not after things get slow
Adding indexes after a table has millions of rows is expensive and disruptive. Design your indexing strategy before go-live.
2๏ธโฃ Stored procedures are not legacy code
They're a performance and security layer. Parameterised stored procedures prevent SQL injection at the database level and run faster than dynamic queries.
3๏ธโฃ Never SELECT * in production
Ever. Always define exactly what columns you need. Schema changes will silently break your application otherwise.
4๏ธโฃ Query ex*****on plans are your best debugging tool
Before blaming the application code, look at the ex*****on plan. Table scans where index seeks should be is almost always the problem.
5๏ธโฃ Test with production-scale data
A query running in 50ms on 10,000 rows can take 45 seconds on 10 million. Your test environment data volume matters enormously.
6๏ธโฃ Keep transactions as short as possible
Long-running transactions hold locks. Locks cause timeouts. Timeouts cause 2am phone calls. None of these are good.
What's the hardest SQL lesson you've learned in production? Share below! ๐
