Unique constraints and unique nonclustered indexes have a lot in common: unique constraints are implemented with a unique index behind the scenes.
While unique nonclustered indexes have a couple of additional features, I can still think of a scenario where it might be best to use unique constraints.
This is one of those little details that confused me a ton when I was first working with execution plans.
One problem with learning to work with plans is that there’s just SO MUCH to look at. And it’s a bit spread out. So, even when looking at a single tooltip, things can be confusing.
Let’s talk about the nested loop operator, who can be particularly weird to understand.
You’d love to have a job tuning SQL Servers, but you don’t have an environment to practice in. Here’s how to teach yourself performance tuning and prepare yourself to land and succeed in job interviews.
You finally got approval to move to new hardware and a fresher version of SQL Server. After months of work, you do the migration and then… performance gets worse. What can cause this, and what do you look for?
I’m excited to announce that I’ll be giving a pre-conference session on index tuning, plus a general session on locking and blocking at the PASS Summit in Seattle this October! Here’s a description and a video to tell you all about these sessions.
For static databases, it’s quite useful to set SQL Server’s “read only” database property to true. When the database is read-only, it ensures that the last backup you took is still valid… as long as nothing bad happens to that backup file.
Update, 6/21/2016: Be careful using indirect checkpoint with failover clusters if your SQL Server 2014 instance is not fully patched. See KB 3166902. This bug was fixed in SQL Server 2016 prior to RTM.
SQL Server 2016 introduces big new features, but it also includes small improvements as well. Many of these features are described in the “It Just Runs Faster” series of blog posts by Bob Ward and Bob Dorr.
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