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INF: RML Utilities: Turning on Trace Flags

INF: RML Utilities: Turning on Trace Flags

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Summary

When using the RML utilities the logged message or documentation can indicate that use of a trace flag is necessary to change behavior.

More Information

The RML Utilities use command line parameter (-T) as a trace flag to alter the utilities behavior.  The term trace flag is a hold over from the SQL Server concept.   Unless otherwise specified the trace flag is NOT a dbcc traceon(##) request.   Instead, add the -T## as a parameter to the command line invocation of the utility.

See:  RML Help Documentation - Trace Flags

References: -T146, -T35, trace flag, ReadTrace, OStress

Bob Dorr
SQL Server Principal Escalation Engineer

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  • Is it possible to force a behavior change on ReadTrace so that it calculate Duration from End-Start?

    I have problems with the microsecond timing in my traces and I can't disable the "clock variation feature" on my servers.

    I ran a stress test with a poorly performing query. My 16-way SQL Server was at 100% all the time.

    I then stress tested a tuned version of the query. The same server stood at 25% to 30% CPU usage all the time.

    The comparision results shows that the tuned query uses less CPU and does less IO, but its duration is "higher".

    Also, the original query scans 2 tables, sorts the results and merge-joins it, while the tuned query does just a non-clustered index seek.

    A digged a lot about the problem and realized that the only explanation for this phenomen is the RDTSC problem.

    Are there any trace flags that can avoid the microsecond timing?

    Thanks in advance!

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