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How it Works: XEL Health Session and Shutdown

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   There are a variety of posts talking about the black box recorder (XEL Health Session) explaining what the recorder is and does: https://blogs.msdn.microsoft.com/psssql/2012/03/08/sql-server-2012-true-black-box-record …

DBCC Trace Flags 2562 and 2549

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Erin Stellato and Jonathan Kehayias from sqlskills reached out asking for clarification of trace flags 2562 and 2549 behavior.  Trace flags 2562 and 2549 are documented in knowledgebase article: https://support.m …

How It Works: Reader / Writer Synchronization

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   This post is not about a specific SQL Server object but instead outlines a technique used in various locations to reduce contention while still providing thread synchronization.  There are hundreds of locations throug …

How It Works: Session/SPID (–2) for DTC Transactions

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   I have written on this subject before but it seems to come up from time to time, as it did again this week.  The Session (SPID) = –2 is just a place holder used by SQL Server to indicate that the DTC t …

COLD, WARM, HOT … CLEAN, DIRTY, FREE … What Does All This Mean?

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   I was asked about these terms from a blog reader.  As I thought about these terms and how to blog about them I became concerned that I might just be as clear as mud, but I will do my best.   Each of the terms mea …

How It Works: Sync IOs in nonpreemptive mode longer than 1000 ms

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Have you encountered the following in your SQL Server error log?         Long Sync IO: Scheduler 95 had 1 Sync IOs in nonpreemptive mode longer than 1000 ms   There are two general types …

Create Table – Disk vs In-Memory Optimized

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   I had an interesting e-mail discussion related to the performance of create table.  The test being executed was a tight loop of create table statements.  The assumption put forth was in-memory optimized table cre …

How It Works: How is SQL Server Error 833, 15 Sec I/O Detected

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   I was approached to revisit the details of how Error Message 833 is detected and reported.   SQL Server has encountered %d occurrence(s) of I/O requests taking longer than %d seconds to complete on file [%ls] in datab …

How It Works: BULK INSERT (BCP) TDS Traffic

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Yesterday I had a discussion with a customer and realized that the BCP, TDS pattern could use a bit of documentation.   Customer Scenario/Question: I am using BCP.exe to import a large data set.   BCP.e …

How It Works (It Just Runs Faster): Non-Volatile Memory SQL Server Tail Of Log Caching on NVDIMM

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Note: We received feedback that there was some confusion on us calling this functionality “tail of the log caching” because our documentation and prior history has referred to the tail of the log as the portion …

SQL Server on Linux: ELF and PE Images Just Work

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Last March I moved from 22 years in SQL Server support to the SQL Server development team, working on SQL Server on Linux project and reporting to Slava Oks.  As Slava highlights in his recent blog post, he also …

SQL Server on Linux: Debugging ELF and PE Images (dbgbridge)

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   In my last post I highlighted the marriage of PE and ELF images within the same process space to build SQL Server on Linux.  In this post I will expand upon the dbgbridge component, as mentioned by Slav …

SQL Server on Linux: An LLDB Debugging Tale

Publié le 24 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   You are aware of our statements indicating “Microsoft Loves Linux.”  Over the last couple of years the open source activities at Microsoft have accelerated all around me.  Recently I blogged about the …

SQL Server on Linux: Scatter/Gather == Vectored I/O

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   Scatter/gather capabilities allow more efficient memory to disk transfers reducing redundant memory copies, sorting and other activities applications may require to gain improved I/O performance.   If my memory serves …

SQL Server On Linux: Core-minidumps and Breakpad

Publié le 23 février 2022 sur MS Tech Community
 

Moved from: bobsql.com   As pointed out in my previous post, debugging on Linux brings a few new twists to those of us used to the Windows debugging landscape.  One of these twists is the need to produce a core dump. On Linux a comm …


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