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CSS SQL Server Engineers

This is the official team Web Log for Microsoft Customer Service and Support (CSS) SQL Support. Posts are provided by the CSS SQL Escalation Services
  • Blog Post: How It Works: When is the FlushCache message added to SQL Server Error Log?

    FlushCache is the SQL Server routine that performs the checkpoint operation.  The following message is output to the SQL Server error log when trace flag ( 3504 ) is enabled. 2012-05-30 02:01:56.31 spid14s     FlushCache: cleaned up 216539 bufs with 154471 writes in 69071 ms...
  • Blog Post: Tracking Down Missing Indexes in SQL Azure

    One of the challenges of SQL Azure is that not all of the TSQL that you are used to using is supported yet.  Since the underlying engine is plain ole’ SQL Server, the engine can understand the TSQL, but we just block its use because we haven’t yet made it work in the multi-tenant, multi-server environment...
  • Blog Post: RML How Are Comparison Diffs Calculated

    A short but good discussion about the RML comparison DIFF calculations.   From: Robert Dorr Sent: Wednesday, January 26, 2011 10:21 AM Subject: RE: MSDN Blogs: Contact request: RML Tools: Estimated Comparison Differences   Thanks for the question and feedback.   For example ProjectedCPUDiff...
  • Blog Post: Doctor, this SQL Server appears to be sick….

    I thought the PASS Summit was a great success this year. I always enjoy speaking at the PASS Summit (this year I spoke on Wait Types. I’m working now on starting to populate the Wait Type Repository ) but I also really enjoy working at the SQL Server Clinic . This year CSS combined its efforts with the...
  • Blog Post: Reduce locking and other needs when updating data - Better Performance

    The following pattern typically stems from an old practice used in SQL 4.x and 6.x days, before IDENTITY was introduced. begin tran declare @iVal int select @iVal = iVal from CounterTable (HOLDLOCK) where CounterName = 'CaseNumber' update CounterTable set iVal = @iVal + 1 where CounterName = 'CaseNumber...
  • Blog Post: Attach of the Clone (… Databases)

    Sorry Star Wars fans to mislead you. I thought our readers should know about a feature we use quite a bit in CSS called a “Clone Database”. It is better publically now known as a “Statistics-Only” copy of the database. Why is this useful? Because it provides CSS a way to reproduce and diagnose query...
  • Blog Post: Q&A on Latches in the SQL Server Engine….

    I recently received a request to shed some light on a few advanced questions about latches and SQL Server. These were good questions so I thought the information might be useful to share with the community. I’ll provide this information in the form of Q&A as I was asked (I’ve paraphrased the questions...
  • Blog Post: An update for Standard SKU Support for Locked Pages….

    Note this article has been updated to include an update for SQL Server 2005 I posted in April that we would be releasing cumulative updates for SQL Server 2008 and 2005 to support the concept of Locked Pages for SQL Server Standard. SQL Server 2008 Cumulative Update 2 for SP1 was released yesterday to...
  • Blog Post: SQL Server reports working set trim warning message during early startup phase

    In the previous posts we have discussed the working set trim message “ A significant part of sql server process memory has been paged out ” that gets written to the SQL Server Error log. You can find the details about the various parameters that determine when this message is written to the error log...
  • Blog Post: Why Should I Use Extended Events in SQL Server 2008?…

    You may or may not have heard of a new diagnostic technology in SQL Server 2008 called Extended Events (XEvent). I thought I would post an example of why this technology can do things nothing else we have can when you deploy SQL Server 2008. Someone internally contacted me about a problem they were having...
  • Blog Post: SQL Server, Locked Pages, and Standard SKU…

    I made an announcement today while speaking at Europe PASS 2009 that we will be providing a method for customers using standard SKU for SQL Server 2005 and 2008 to use the ‘Locked Pages in Memory’ privilege to allow the server to use the AWE APIs. This is often referred to as “locked pages” for SQL Server...
  • Blog Post: SQL Server and the Bad CPU

    From time to time I encounter an issue where the physical CPU is the source of the problem.   I hope you never encounter such and issue but I wanted to provide an example to help those that will. Customer started getting frequent dumps from the SQL Server process.   Looking at the...
  • Blog Post: SQLDumper unable to generate mdmp files in SQL Server 2008 Failover clusters

    SQLDumper utility is used by various components of the product to generate and save diagnostic information in the form of mini-dump and other log files. You will normally find the output files [with extension .mdmp, .txt and .log] created by sqldumper.exe in the LOG folder of the specific instance for...
  • Blog Post: Sparse File Errors: 1450 or 665 due to file fragmentation: Fixes and Workarounds

    You might be familiar with the sparse file problem that Bob Dorr has blogged about in the past. http://blogs.msdn.com/psssql/archive/2008/07/10/sql-server-reports-operating-system-error-1450-or-1452-or-665-retries.aspx . We wanted to update you with the work we have been involved in the past few months...
  • Blog Post: You encounter error message "The system cannot find the file specified" when attempting to perform backups using sqlvdi

    Symptoms you encounter: SQL Server 2000 SP4 x86 is installed on a Windows 2003 X64 server. You use x64 backup applications to perform backups of databases. These backup applications use sqlvdi to interact with the SQL Server. You installed the sqlvdi.dll from KB 913100 and the x64 backup applications...
  • Blog Post: SQL Server 2005 or 2008 Reporting Error 17883 - Stalled Scheduler Warnings

    SQL Server 2005 introduced a background worker to flush trace event streams.   The trace buffer is flushed when it becomes fully populated but a partially populated trace buffer remains in-memory until events fill the buffer or the background worker flushes the events to the stream.  Periodically...
  • Blog Post: SQL Server: Is CHECKDB A Necessity?

    From: SQL Server Customer Sent: Friday, February 20, 2009 5:08 AM   I’m often asked by professionals whether CheckDB is still recommended on SQL2k8.  SQL is calculating a checksum to avoid physical page corruption since 2k5. However in my experience (starting with SQL 7.0) I’ve...
  • Blog Post: SQLIOSim: Default Testing Pattern

    The SQLIOSim knowledge base article outlines the various configuration files in detail.  http://support.microsoft.com/kb/231619 - How to use the SQLIOSim utility to simulate SQL Server activity on a disk subsystem. I still get inquires about what should I run by default.   My answer is...
  • Blog Post: SQL Server (2005 and 2008) Trace Flag 1118 (-T1118) Usage

    Trace flag 1118 forces uniform extent allocations instead of mixed page allocations.   The trace flag is commonly used to assist in TEMPDB scalability by avoiding SGAM and other allocation contention points. SQL Server 2008 optimized mixed extent allocation behavior reducing the need for trace...
  • Blog Post: Should I run SQLIOSim? - An e-mail follow-up from SQL PASS 2008

    From: Robert Dorr [mailto:rdorr@microsoft.com] Sent: Thursday, November 20, 2008 11:29 AM To: A SQL PASS MEMBER - CSS First Aid Station Question About SQLIOSim As we discussed at SQL PASS – SQLIOSim is an independent utility and has been used as part of the Windows Hardware Compatibility Testing...
  • Blog Post: SQL Server 2005 Encounters Exception During Install When System has Odd Number of Processors or Logical Processors Per Core

    While attempting to install SQL Server 2005 you may encounter an error familiar to the following and a retry option presented by setup. Faulting application sqlservr.exe, version 2005.90.1399.0, time stamp 0x434f82e9, faulting module sqlservr.exe, version 2005.90.1399.0, time stamp 0x434f82e9, exception...
  • Blog Post: SQL Server reports operating system error 1450 or 1452 or 665 (retries)

    Overview The error: 1450/1452 insufficient system resources exist to complete the requested service. These are not a SQL Server based errors. The error cause is related to a depleted system resource (non-paged pool, paged pool ,...). These issues have to be tracked down at the operating system level...
  • Blog Post: SQL Server I/O Bottleneck, I don't have one, YES YOU DO!

    The mistake I see people make is when looking at the SQL Server PAGE I/O waits and stalled I/O warnings is when comparing it to the Avg. Disk Seconds/Transfer.    Everyone seems to forget that average means average and they look at the value and say I don't see any I/O taking longer than...
  • Blog Post: Query Performance issues associated with a large sized security cache

    In the past couple of months, SQL Server support team has come across some customers running into performance issues attributed to TokenAndPermUserStore in SQL Server 2005. This blog post attempts to compile all the information we have so far regarding this problem. TokenAndPermUserStore is one...
  • Blog Post: How It Works: SQL Server 2005 - Possible data recovery when checksum failure reported

    I and Microsoft will always opt for restore of a backup when corruption of the database is encountered.   This is the only way to safely restore the database to a known state.   All other actions, such as dbcc repair, can remove data from the database and break referential integrity...
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