You Come And Go
I go back and forth when it comes to Lookups.
On the one hand, I don’t think the optimizer uses them enough. There are times when hinting a nonclustered index, or re-writing a query to get …
Category: Isolation Levels
Help! My SQL Server Query Got Slower Without A NOLOCK Hint!
(NOSERIOUSLY)
Going Further
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In SQL Server, Isolation Levels Don’t Control Locking
Different Engines
I seem to have gotten quite a few questions about this lately, so I’m going to write down some thoughts here.
It’s probably crappy form for a blog post, but what the heck.
Queries Decide The Isolation Level
…When Read Queries Block Write Queries In SQL Server
Gritty
You may occasionally see in your favorite monitoring tool, or Most Fantastic And Glorious Script For Determining Whom Activity Belongs To™ that a read query, perhaps even a long running one, is blocking modification queries.
Under most circumstances, …
SQL Server Index Key Column Order And Locking
Fall Guy
Let’s say we have a super important query. It’s not really important.
None of this is important.
SELECT u.DisplayName, u.Reputation, u.CreationDate FROM dbo.Users AS u WHERE u.CreationDate >= DATEADD(DAY, DATEDIFF(DAY, 0, GETDATE()), 0) AND u.Reputation < 6 ORDER…
Should An Optimistic Isolation Level Be The New Default For SQL Server Databases?
Two Words
Alright, I’ve lied to you already. There are way more than two words involved, here.
I recently had breakfast (JUST BREAKFAST, GOD) with Microsoft’s Most Handsome Man™, and the topic came up.
Partially because there are such fundamental …
The Real Value Of Optimistic Isolation Levels In SQL Server
Erroneous
While a lot of people speak highly of optimistic locking because it cuts down on blocking issues, I think it’s of equal or higher value that dirty reads are prevented.
“Imagine” a situation where someone ran a query they …
Isolation Levels Are Inherited In SQL Server Queries
Client Yell
While working with a client who has a nasty blocking problem involving triggers, we were talking about using Snapshot Isolation to help fix the issue.
The thing is, there’s more than just stored procedures causing problems. Some of …