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SQL tuning task generates suboptimal profiles

edited Sep 26, 2013 1:25AM in SQL Performance (MOSC) 2 commentsAnswered
Hi all,

I wonder if anyone can help me on this one.

The situation is like this: I have a particular long running SQL. Statistics are current, also i/o calibration and system stats are gathered. PARALLEL_DEGREE_POLICY is set to AUTO and parallel server parameters are set properly. The database is quite well tuned otherwise, and parallel execution plans are being generated all the way.

Now this one partcular SQL refuses to get optimized for parallel execution. When executed normally, a index based execution plan is being generated and execution takes about 30 minutes. After running a manual tuning task, a slightly different plan is generated (still serial execution) and execution time stays around 30 minutes.

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