I've recently found out that there's a bug some people are hitting when running DBCC CHECKDB on SQL Server 2005 – you get an error like: Msg 831, Level 20, State 1, Line 1 Unable to deallocate a kept page. This is a bug in the database snapshot code, and shows up sometimes when running DBCC [...]
Paul S. Randal
In Recovery...
(Not a) CHECKDB error “Unable to deallocate a kept page”
Posted on: March 29, 2011 11:10 am
DBCC CHECKFILEGROUP bug fixed in 2008 SP1 CU6
Posted on: January 25, 2010 10:47 am
Back in September I blogged about an old 2005 bug that prevented DBCC CHECKFILEGROUP checking the partitions of an object on the specified filegroup unless *all* partitions of the object are on the specified filegroup (not a smart way to set things up!). The bug was fixed ages ago in 2005 but has only just [...]
Diskeeper 10 Intelliwrite corruption bug
Posted on: January 13, 2010 2:34 pm
A couple of years ago I blogged about 3rd-party file system filter drivers and how if they're not coded correctly to cope with NTFS alternate streams they will cause all kinds of weird corruption errors to be reported when DBCC CHECKDB is running. At the time I'd only seen the issue a couple of times so thought [...]
Interesting 2008 partitioned view perf bug fixed in SP1 CU4
Posted on: December 3, 2009 11:28 am
This is an interesting performance bug concerning a broken query optimizer rule in 2008. Thanks to Dan Shargel (Twitter) for sending me info on this and letting me use some of the stuff he sent. The scenario involves using MIN or MAX in a query against a partitioned view. In 2005 the query plan includes [...]
2005 corruption bug with XML index rebuild fixed in latest CU
Posted on: December 2, 2009 5:04 pm
2005 SP3 CU6 contains a fix for a corruption bug that can happen after rebuilding an XML index that contains XML elements greater than 8000 bytes. The bug was fixed in 2008 but hadn't made it back to 2005 until the last CU was released. I had email from someone back in August experiencing corruption [...]
What is FSAgent.exe and why does it have lots of waits?
Posted on: May 6, 2009 4:21 pm
Another quickie today. If you're using Activity Monitor in SQL Server 2008, or Performance Data Collection with the Server Activity system data collection set, then you may see a constant, and large number of 'Other' SQL Server Waits. When you drill into these, you see that the highest number of waits are for FSAgent. The FSAgent is [...]
Performance bug: NOLOCK scans involving off-row LOB data
Posted on: April 30, 2009 5:34 pm
Here's an interesting bug that was just recently fixed, and someone actually hit it today, so it's time to blog it. Bottom line is that if you're doing NOLOCK scans of tables involving LOB data, the perfmance might suck. 2005 SP3 CU3 has the bug fix, but unfortunately the KB article was written by someone [...]
MS announces support for ‘lock pages in memory’ for Standard Edition
Posted on: April 26, 2009 8:33 pm
Finally! All those customers out there who are frustrated by not being able to turn on the 'lock pages in memory' option to protect the SQL working set on Standard Edition – the wait is nearly over. Bob Ward (Principal Escalation Engineer in CSS, and a good friend of mine) announced at PASS Europe that [...]
SQL 2005 SP2 maintenance plan bug masking corruption
Posted on: April 15, 2009 11:54 pm
Not much to do here in Tokyo while waiting for the Bangkok flight except read and blog, and I've already done enough reading for one day on the flight here – so that leaves blogging! Here's an interesting case that I got involved in on SQLServerCentral (here's the original thread, linked here with permission of [...]
SQL Server 2008 SP1 has been released
Posted on: April 7, 2009 7:17 pm
See http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=66ab3dbb-bf3e-4f46-9559-ccc6a4f9dc19 for the download, release notes, etc
Couple of LOB corruption bugs fixed in the latest CUs for 2005
Posted on: March 10, 2009 4:49 pm
Both 2005 SP3 CU2 and 2005 SP2 CU12 contain fixes for two bugs that cause corruption in LOB data. The first bug may happen when a column type is converted to varbinary(max), change the large-value-types-out-of-row option to true, insert a row, and then try to update it – described in KB 961648. The second bug [...]
Rolling upgrade using database mirroring (and a bug in 2008 RTM)
Posted on: February 24, 2009 11:00 am
While trawling through the latest 2008 Books Online this morning to answer a question, I noticed a new section that I hadn't seen before, which explains in detail how to perform a rolling upgrade with database mirroring. The link to the MSDN page is http://msdn.microsoft.com/en-us/library/bb677181.aspx and below I've linked to the flowchart from that page. Books [...]
Couple of nasty FILESTREAM bugs fixed in 2008 RTM CU1
Posted on: February 23, 2009 12:29 pm
Cumulative Update 1 for SQL 2008 RTM contains fixes for two nasty FILESTREAM bugs (among a lot of other bug fixes). The first one concerns restoring a 2008 database from a series of log backups when the database contains FILESTREAM info. It's possible that a race condition can cause one of the log backups to [...]
