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Poor performance from single database


Poor performance from single database

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dmcquade
dmcquade
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I have a 2005 SQL server running about 20 databases identical in design. Each database is accessed by one or 2 users simultaneously. Performance is fine for all except 1 database. The size of the files are relatively small compared to all of the other databases files. Each database is accessed from the same terminal server so I know the problem is not a workstation issue. Running a query to get sysprocesses sorting bu CPU shows a wait type of SOS_SCHEDULER_YIELD and the cmd is SELECT when accessing that database.

Any suggestions on how to go about troubleshooting this performance issue would be greatly appreciated.
dmcquade
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Identified the offending SELECT statement. Now trying to figure out why this SELECT statement runs slower on this database than it does on all the others.
TheSQLGuru
TheSQLGuru
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Try a profiler run to capture poorly performing statements. Also use PerfMon and Task Manager to capture performance metrics. Your indications suggest CPU issues. Find bad query(s) and tune appropriately. One possible thing is out of date stats leading to bad plan. Another is someone dropped an index (or one is needed due to data skew, etc).

Best,
Kevin G. Boles
SQL Server Consultant
SQL MVP 2007-2012
TheSQLGuru on googles mail service
WolfgangE
WolfgangE
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As you already identified the SELECT statement check the indexes on all referenced tables.

Don't forget to check the overall server performance. SOS_SCHEDULER_YIELD could be a hint that the processor is busy. Maybe not the database is the problem but other processes on the server so that there are not enough ressources left for sql server.
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