Last week I wrote a post on Isolation Levels and the Effects on Select Statements, and I had a conversation on Twitter with Rob Farley ( b | t ) regarding one of my explanations. For READ COMMITTED, I had written the following: If data is being modified by a transaction, any subsequent select statement…
Category Archives: Internals
Isolation Levels and the Effects on Select Statements
Database locking is a fundamental concept in SQL Server that every Database Administrator and Database Developer should understand. SQL Server has a pessimistic locking model because it was built for an OLTP environment and assumes that updates will occur frequently. For a developer, this is important to understand in terms of concurrency: how many users…
Page Allocation: Dedicated vs. Mixed Extents
When I was at a SQLSaturday a few months ago, I attended a session that hit upon SQL Server Internals, one of my favorite topics. During the session the presenter was talking about page allocation, and mentioned that pages for a table and its indexes will reside in the same extents. Now, I remember immediately…
Ready for Training: The Content
Next week I am heading to Seattle for 5 days of SQLskills training. In honor of the event (yes, I’m that excited about it and I’ve deemed it an event), I thought I’d do 5 days of posts covering what I’m looking forward to and why. I. The Content For anyone not familiar with SQLskills and…
