Every batch (T-SQL, SP etc) when ran creates execution plan which is stored in system for re-use. Due to this reason large number of query plans are stored in system. However, there are plenty of plans which are only used once and have never re-used again. One time ran batch plans wastes memory and resources.

SQL Server 2008 has feature of optimizing ad hoc workloads. Before we move to it, let us understand the behavior of SQL Server without optimizing ad hoc workload.

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