Learn T-SQL Querying

Degree of Parallelism*

Degree of Parallelism* indicates the number of CPUs actually used to process a query that was eligible to execute in parallel. In this case, we see the value is zero (0) because the query was not executed in parallel. We have discussed how the query optimization process evaluates parallelism in the Chapter 3, Mechanics of the Query Optimizer. If the query had a cost that was high enough to go parallel but didn't, an extra property named NonParallelPlanReason* is also shown. In this case, we can see the reason was MaxDOPSetToOne, and indeed notice the query used the MAXDOP 1 hint, forcing the Query Optimizer to not evaluate a parallel plan. Compare this with the EstimatedAvailableDegreeOfParalellism property; for example, ...