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Are INSERTs serialized because of row group locks? No. If a trickle INSERT requires an OPEN row group and it cannot place a lock on it it will create a new one. any number of INSERT statements can proceed in parallel, each locking its own row group. While Read More...
One of the most common complains about using Service Broker in production is when administrators discover, usually after some months of usage, that sys.conversations_endpoints grows out of control with CLOSED conversations that are never cleaned up. I Read More...
The SQL Server transaction log contains the history of every action that modified anything in the database. Reading the log is often the last resort when investigating how certain changes occurred. It is one of the main forensic tools at your disposal Read More...
So you have this SQL Server database that your application uses and it somehow seems to be slow. How do you troubleshoot this problem? Where do you look? What do you measure? I hope this article will answer enough questions to get you started so that Read More...
Recently I had to investigate a deadlocked Windows Server 2012 machine. Any attempt to start or stop a service on this machine would freeze in an infinite wait. I did not know about the “Analyze Wait Chain” feature in the Task Manager (new Read More...
If you are a developer writing applications that use SQL Server and you are wondering what exactly happens when you ‘run’ a query from your application, I hope this article will help you write better database code and will help you get started Read More...
SQL Server 2012 installation has the potential to leave an msiexec.exe installer process running after the installation finishes, as described in Windows Installer starts repeatedly after you install SQL Server 2012 SP1: After you install SQL Server 2012 Read More...
I noticed that my database log file has grown to 200Gb. I tried to shrink it but is still 200Gb. How can I shrink the log and reduce the file size? The problem is that even after you discover about DBCC SHRINKFILE and attempt to reduce the log size, the Read More...
In a previous article Online non-NULL with values column add in SQL Server 2012 I talked about how adding a non-null column with default values is now an online operation in SQL Server 2012 and I mentioned how the situation when the newly added column Read More...
with xmlnamespaces (default 'http://schemas.microsoft.com/sqlserver/2004/07/showplan') select x.value(N'@NodeId',N'int') as NodeId , x.value(N'@PhysicalOp', N'sysname') as PhysicalOp , x.value(N'@LogicalOp', N'sysname') as LogicalOp , ox.value(N'@Database',N'sysname') Read More...
You probably can easily answer a question like ‘What columns does this table have?’. Whether you use the SSMS object explorer, or sp_help, or you query sys.column, the answer is fairly easy to find. But what is I ask ‘What are the physical Read More...
Certain SQL Server query execution operations are calibrated to perform best by using a (somewhat) large amount of memory as intermediate storage. The Query Optimizer will choose a plan and estimate the cost based on these operators using this memory Read More...
A new error started showing up in SQL Server 2008 SP2 installations: The database cannot be opened because it is version 661. This server supports version 662 and earlier. A downgrade path is not supported. 661 sure is earlier than 662, so what seems Read More...
In a stackoverflow.com question the user has asked how come a SELECT statement could own a U mode lock? The deadlock indeed suggests that the deadlock victim, a SELECT statement, is owning an U lock on the PK_B index. Why would a SELECT own an U lock? Read More...
Some say performance troubleshooting is a difficult science that blends just the right amount of patience, knowledge and experience. But I say forget all that, a few bullet points can get you a long way in fixing any problem you encounter. Is more important Read More...
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