WITH (NOLOCK) and WITH (READPAST) are SQL Server table hints that manage concurrency differently — NOLOCK reads uncommitted (dirty) data, while READPAST skips locked rows, avoiding dirty reads but potentially missing data. With(NoLock) v...
By Huy Vũ
Exception handling can make or break your application. If exceptions aren’t handled properly, your API could leak sensitive stack traces, return inconsistent error formats, or worse - crash entirely. I’ve seen production systems go down ...
By Huy Vũ
Slapping WITH (NOLOCK) on your query seems to make it go faster – but what’s the drawback? Let’s take a look. We’ll start with the free StackOverflow.com public database – any one of them will do, even the 10GB mini one – and run this qu...
By Huy VũI’ve already covered how NOLOCK gives you random results when you’re querying data that’s changing, and that’s a really powerful demo to show folks who think NOLOCK is safe to use in production. However, I’ve gotten a question from sever...
By Huy Vũ
How to change isolation levels without losing your marbles. A client said the coolest thing to me the other day. He said, “We talked before about why we would want to start using optimistic locking in our code. How do we get there?” If y...
By Huy Vũ
When you run a SELECT COUNT(*), the speed of the results depends a lot on the structure & settings of the database. Let’s do an exploration of the Votes table in the Stack Overflow database, specifically the 2018-06 ~300GB version where ...
By Huy Vũ