Can’t I ever get a guarantee?

I’ve been sitting and thinking a lot about guarantees this morning while drinking coffee in the debilitating heat here (85 degrees at 11am) and things get more complicated the more I think about it, so time to stop and post some thoughts. Over the last few days, the question of guarantees has come up several times… Read more

Scale-up technology

Totally off-topic post today. We recently had a private tour of the excellent Woodland Park Zoo here in Seattle. While we were there, I had the opportunity to meet the ultimate in flesh-and-blood scale-up technology… And as you can see, it was love at first sight 🙂 I wonder if I could keep a giraffe in my… Read more

CHECKDB (Part 3): What does CHECKDB really do? (2 of 4)

In the previous post of this series, I covered the system table checks that have to be done before anything else can be checked by CHECKDB. Now that I’ve described pages, extents, IAM chains/allocation units and the major allocation bitmaps, in this post I’ll cover the allocation checks. 1. Primitive checks of critical system tables(Part 1…)… Read more

Checksum in SQL2005

Page checksum is new feature in SQL2005 that provides you a stronger mechanism than torn-page to detect any corruptions in IO path. Here are some details and scenarios   PAGE CHECKSUM:   Between the time a database page is written to the disk and subsequently read by SQL Server, it may get corrupted for reasons… Read more

Why is the NULL bitmap in a record an optimization?

I’ve had some questions sent in comments and I wanted to reply to some of them using a post so others who aren’t subscribed to the comment sections can see the answers.   Wesley Backelant said: I was wondering what exactly you mean by “this allows an optimization when reading columns that are NULL”.  Could you elaborate… Read more

Fragmentation (part 3): What are extents?

(Ok – another flight – another blog post. This time its Boston back to Seattle. The three of us who’d come over for the training course upgraded to 1st Class on Alaska for the flight back (great value at $100 for a 6-hour flight) and so there’s oodles of room for laptops, newspapers, and long… Read more

Fragmentation (part 2): What are pages?

(Boston continues its reputation – with me at least – for great seafood – calamari and pan-seared fresh halibut this evening. Yum! I was tempted to get on the T – Boston’s subway system – and see what’s happening downtown but with no jacket I’d get wet. So, instead I’ll be boring and geeky and… Read more