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How It Works: SQL Server Deadlock Trace Flag 1222 Output

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com The trace flag 1222 can be very powerful and helpful in tracking down the cause of a deadlock when used correctly.   This week I was tracking down a blocking situation, which I expected the lock monitor to resolve …

SQL Server Mysteries: The Case of the Suspended, Awaiting Command, and Blocked Session

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   I ran into a scenario showing my session as suspended, awaiting command and blocked!  My first thought was that this had to a bug. As many of us have documented, for years, a sleeping, awaitin …

SQL Server Management Studio Provides–“XE Profiler”

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Bob Ward and I worked with our SQL Server Tool developers (thanks David) to enable ‘Quick XE Trace’ capabilities. The feature is available in the latest SQL Server Management Studio (SSMS) releas …

How It Works: SQL Server DTC (MSDTC and XA Transactions)

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   I have found the term DTC is used in many ways so for the purposes of the discussion here are a few terms.  When talking DTC, I am talking about the feature set, MSDTC as the OLE-TX implementation and XA for the X/Ope …

SQL Server on Linux: Kerberos Troubleshooting, Hints and Tips and Hard Code Debugging

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   SQL Server on Linux uses the GSSAPI and SSSD service for Active Directory (AD) authentication activities.   Thus, Kerberos is the path for success for AD authentication and just in case you ha …

SQL Server on Linux: CU4 – NewSequentialId() – Uuid

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Prior to SQL Server 2017 CU4 for Linux (Linux only) the generation of a sequential UUID may not function as expected.  SQL Server’s NewSequentialId() calls the Windows API UuidCreateSequentia …

SQL Server 2017 Improved Resource Usage On Smaller Machines

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   What does improving resource usage on smaller machines really mean? https://support.microsoft.com/en-us/help/4078095 SQL Server is designed to scale across the spectrum of small machines to enterprise class servers. …

SQL Server on Linux: Why Do I Have Two SQL Server Processes?

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   When starting SQL Server on Linux why are there two (2) sqlservr processes?   systemctl status mssql-servermssql-server.service – Microsoft SQL Server Database Engine…   CGroup: /system.slice/ms …

SQL Server on Linux: How is Delete-On-Close Handled

Publié le 22 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Windows provides an option for CreateFile to delete a file when the file is closed (FILE_FLAG_DELETE_ON_CLOSE.)     Host Extension Handling Linux does not expose such an option as part of the  …

SQL Server Mysteries: The Case of the Dropped AD Group Login

Publié le 22 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Dylan (who kindly wrote up the contents of this blog for me) was modifying the tests for Active Directory Login activities.  As Dylan and I reviewed the changes a specific behavior involving Active Directory Group Log …

SQL MYSTERIES: Tracing BCP Might Fool You

Publié le 22 février 2022 sur MS Tech Community
 

Moved from bobsql.com   Today I was tracking a large BCP.exe ‘IN’ operation and monitoring the sys.dm_exec_requests entries.  The ‘BULK INSERT’ command entry appeared, showing the CPU, reads, writes, … …

SQL Server Instant File Initialization: SetFileValidData (Windows) vs fallocate (Linux

Publié le 22 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   SQL Server Books Online documents Instant File Initialization and the associated security considerations.   This blog highlights the underlying file system implementations and differences in behavior be …

SQL Server On Linux: Forced Unit Access (Fua) Internals

Publié le 22 février 2022 sur MS Tech Community
 

Moved from: bobsql.com Overview SQL Server relies on Forced-Unit-Access (Fua) I/O subsystem capabilities to provide data durability, detailed in the following documents: SQL Server 2000 I/O Basic and SQL Server I/O Basics, Chapter 2 …

SQL Server Linux: fsync and Buffered I/O

Publié le 22 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   I was asked to validate  the SQL Server behavior in light of the error condition involving fsync/fdatasync outlined in this article.    An example of the error: The application does …

SQL Server Linux: Directory fsync Activities

Publié le 22 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   When Creating, Renaming or Deleting (remove/unlinking) a file, Linux requires the direct parent directory to be synchronized.  As documented in the manpage for fsync core changes to the directory require the …


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