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• DBCC
• DBCC CHECKDB Series
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• Index Fragmentation Series
• TechEd 2006

• CHECKDB (Part 8): Can repair fix everything?

  I was teaching at a Microsoft-internal class last week and there was a discussion on what corruptions can't be repaired using DBCC. At the same time, several threads popped up on forums and newsgroups with people hitting some of this unrepairable corruptions Read More... Posted Sunday, February 04, 2007 4:53 PM by Paul Randal - MSFT | 3 Comments Filed under: DBCC, Disaster Recovery, DBCC CHECKDB Series, On-Disk Structures

• More undocumented fun: DBCC IND, DBCC PAGE, and off-row columns

  (Final blog post of the year for me. Its been a bit of a wild ride the last 6 months - 7 TechEds on 3 continents, 46 blog posts and some major life changes - but now things have calmed down and I should be back to more regular posting in 2007. Tomorrow Read More... Posted Wednesday, December 13, 2006 10:46 PM by Paul Randal - MSFT | 11 Comments Filed under: DBCC, Index Fragmentation Series, On-Disk Structures

• When can allocation order scans be used?

  I know this is jumping the gun a little as I haven't made it this far in my series on fragmentation , but this came up in a chalk-talk I did yesterday at TechEd Developers in Barcelona and is worth blogging about. You'd expect a select * from mytable Read More... Posted Thursday, November 09, 2006 2:31 AM by Paul Randal - MSFT | 8 Comments Filed under: TechEd 2006, Index Fragmentation Series, On-Disk Structures

• Fragmentation (part 4): what are heaps?

  Ok - really catching up with the various blog post series I started back in June/July - time to bang out the next few posts in the series on index fragmentation. Remember I'm starting from first principles and covering What are records? What are pages? Read More... Posted Tuesday, September 19, 2006 2:18 AM by Paul Randal - MSFT | 9 Comments Filed under: Index Fragmentation Series, On-Disk Structures

• Don't try this at home kids... (data recovery using DBCC PAGE)

  Time to cough up a real-life data recovery scenario to temporarily stop those people who badger me relentlessly for scenarios... We have a situation currently with a customer who managed to delete all their data during a SAN reconfig and then found out Read More... Posted Wednesday, August 09, 2006 8:41 PM by Paul Randal - MSFT | 5 Comments Filed under: DBCC, Disaster Recovery, On-Disk Structures

• Poking about with DBCC PAGE (Part 1 of ?)

  (It's been a while since I last posted - summer fun's been in the way obviously and I've been busy picking up some new and exciting (for me) SQL skills, partially to help with four upcoming TechEds I'll be doing in China and Hong Kong. The posting frequency Read More... Posted Wednesday, August 09, 2006 2:52 AM by Paul Randal - MSFT | 6 Comments Filed under: DBCC, On-Disk Structures Attachment(s): Data.zip

• Under the covers: GAM, SGAM, and PFS pages

  (Been a week or so since the last post but I haven't burnt out with blogging yet - I was on vacation over the July 4th weekend and totally offline in and around a small town called Pullman in south-eastern Washington.) In a previous post I described extents, Read More... Posted Saturday, July 08, 2006 2:22 PM by Paul Randal - MSFT | 4 Comments Filed under: On-Disk Structures

• 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 Read More... Posted Thursday, June 29, 2006 2:42 AM by Paul Randal - MSFT | 2 Comments Filed under: On-Disk Structures

• 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 Read More... Posted Wednesday, June 28, 2006 6:52 PM by Paul Randal - MSFT | 8 Comments Filed under: Index Fragmentation Series, On-Disk Structures

• Under the covers: IAM chains and allocation units in SQL Server 2005

  (I'm sitting here in Seattle airport at 7am on Sunday waiting to catch the same flight to Boston that I caught two weeks ago. Instead of TechEd, this time I'm going to a training course at MIT. I'd enjoy the air travel a lot more with a bigger gap in Read More... Posted Sunday, June 25, 2006 11:01 PM by Paul Randal - MSFT | 5 Comments Filed under: On-Disk Structures

• 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. Read More... Posted Monday, June 26, 2006 2:56 AM by Paul Randal - MSFT | 13 Comments Filed under: Index Fragmentation Series, On-Disk Structures

• Under the covers: IAM chains in SQL Server 2000

  I've reached a point in my various ramblings where I need to do some glossary work. First up is an explanation of IAM chains. This will be in two parts, detailing how they're used in SQL Server 2000 and then in 2005. (Probably tomorrow as the sun's shining Read More... Posted Saturday, June 24, 2006 3:24 PM by Paul Randal - MSFT | 4 Comments Filed under: On-Disk Structures

• Fragmentation (part 1): What are records?

  This blogging thing sucks you in, doesn't it? Not content with having an ongoing series on disaster recovery and CHECKDB (with another 6 and 25 more posts planned respectively), I'm starting a new series on fragmentation. This will begin from first principles Read More... Posted Friday, June 23, 2006 4:41 PM by Paul Randal - MSFT | 18 Comments Filed under: Index Fragmentation Series, On-Disk Structures

• How to use DBCC PAGE

  Yes, finally I come clean and tell all. It's an open secret that there's an undocumented DBCC command called DBCC PAGE that you can use to look at the contents of database pages. I've recommended in forum postings that people use it and Product Support Read More... Posted Saturday, June 10, 2006 7:14 PM by Paul Randal - MSFT | 9 Comments Filed under: DBCC, Disaster Recovery, On-Disk Structures