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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: DReplay Message: “Active connections exceed 8192, connection 8409 is waiting.”

    This message was an interesting dive into the DReplay, session boundary logic that I thought I would share.  Internally DReplay maintains a progressive, session queue.  This queue is limited to 8192 entries and populated in connection replay order based on the connect/disconnect boundaries...
  • Blog Post: SQL Server: Correlating Timestamps From Various Data Points

    I was looking at data from a customer, in a different time zone (UTC+1) from mine, this week involving SQL Server AlwaysOn (HADRON) and found that lining up the timestamps in the various logs was challenging.   Some times are local to the SQL Server instance, others UTC and yet other utilities...
  • Blog Post: Easy JDBC Logging

    I have been supporting Microsoft’s JDBC driver for almost six years now and the one thing with which I always struggle is getting logging going.  JDBC logging is probably some of the most useful logging out there (I only wish BID tracing were so easy to enable and consume!), but for some reason...
  • Blog Post: Trace shows the incorrect Session Login Name

    The is more of an FYI blog post but I have read several blog and forum posts on this subject and I decided to dig into the behavior which revealed a trace bug. For the vast majority of events the Session Login Name represents the originating session credentials where as the Login Name represents the...
  • 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: Profiler Shows Negative (Strange) EventSequence Values

    I ran into an issue yesterday where the EventSequence column appears negative (or could be truncated and won't sort correctly) in the Profiler display. Here is an example of the display from a trace that I debugged. When I looked at the raw format I could see the storage for the EventSequence was 8 bytes...
  • Blog Post: Replay Result Set Event (Replay * Events)

    From: Robert Dorr Sent: Friday, August 13, 2010 8:58 AM Subject: RE: SQL Server Trace Replay - "Replay Result Set Event" The Result Set event is one of several client side replay events. Here are some of Common Result Event Columns Text Returned values for example DECLARE @edition sysname;...
  • Blog Post: INF: Multi-Machine Replay Using ORCA and OSTRESS

    You can place ORCA on a central computer and allow it to control the sequencing from multiple client computers running OSTRESS.    To accomplish this you must configure the firewall properly. Note: Be sure to install the same version of the RML utilities on all machines.   ...
  • Blog Post: ReadTrace Generates Unexpected Connect Node - Not Really

    At first glance it appears that ReadTrace has generated an unexpected connect node.  Upon closer inspection the behavior is correct in order to maintain the proper set options for the connection. Trace has both physical and logical connect/disconnect events.   The logical is indicated...
  • Blog Post: Filtering Trace Data Without Loading In Profiler or Database Table

    We are often asked how to extend the filtering of RML (ReadTrace/OStress) or Profiler.  Filtering during trace production is the preferred method because it typically reduces the overall impact of the Trace on the SQL Server throughput.   For late filtering you can generally use the Profiler...
  • Blog Post: How It Works: SQL Server No Longer Uses RDTSC For Timings in SQL 2008 and SQL 2005 Service Pack 3 (SP3)

    Many of you have encountered the RDTSC timing variances that I outlined in an earlier blog post:   http://blogs.msdn.com/psssql/archive/2006/11/27/sql-server-2005-sp2-will-introduce-new-messages-to-the-error-log-related-to-timing-activities.aspx and http://blogs.msdn.com/psssql/archive/2007...
  • Blog Post: How It Works: Attention, Attention or Should I say Cancel the Query and Be Sure to Process Your Results

    I ran into this issue the other day and decided it would make a good post.  Since I have seen this issue more times that I can count I will again attempt to provide details. The attention event in SQL Server trace output indicates a query cancellation.   There are three common ways this...
  • Blog Post: How It Works: Trace (.TRC) File Security

    SQL Server 2000 shipped with different trace file security than later builds of SQL Server 2000, SQL Server 2005 and SQL Server 2008. The SQL Server process (sqlservr.exe) writes the trace files to the specified destination.   The SQL Server 2000 release did not explicitly set the ACLs on the...
  • Blog Post: How It Works: Conversion of a Varchar, RPC Parameter to Text from a Trace (.TRC) Capture

    The Senior Escalation Engineers do various training and mentoring activities. As I do this I thought I would try to propagate some of this information on the blog. This was an interesting issue I ran into this week. The reported problem was that the data shown as TEXT for an RPC event did not match...
  • Blog Post: SQL Server 2005 - RDTSC Truths and Myths Discussed

    I posted some updates to my blog entry about the RDTSC and drift warnings in May. See the following link http://blogs.msdn.com/psssql/archive/2006/11/27/sql-server-2005-sp2-will-introduce-new-messages-to-the-error-log-related-to-timing-activities.aspx Because the CPU drift issue has continued to generate...
  • Blog Post: SQL Server 2005 SP2 – Trace Event Change – Connection Based Events

    Starting with SQL Server 2005 SP2 the connection based events are also produced for sp_reset_connection activities, indicating the connection was reset. The pattern will look like the following. RPC:Starting sp_reset_connection Disconnect Subclass = 2 RPC:Completed sp_reset_connection Connect Subclass...
  • Blog Post: SQL Server 2005 SP2 will introduce new messages to the error log related to timing activities.

    The following article has been publiched about this subject: http://support.microsoft.com/kb/931279 RDTSC Drift vs Not Synchronized To clarify - SQL Server 2005 SP2 contains both Drift and a Non Synchronized warnings. The Non Synchronized message is only recorded on 1 hour intervals...
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