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Compute Scalar Operators: Why a Computed Column Shows Two

A plan that reads a computed column shows two Compute Scalar operators, and the second one looks like a mistake. This post compares three tables in the plan text: an expression in the query, a computed column and a persisted computed column. It shows what each of the Compute Scalar operators defines and whether the extra operator costs anything.

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Execution Plan Wait Stats: Read Them in SSMS and XML

Execution plan wait stats list what one execution of a query waited for, so you don’t have to guess from server-wide totals. This post shows where to find them in SSMS and in the plan XML, reproduces a lock wait with two query windows, and explains the common wait types. It ends with Query Store, which keeps wait totals for many queries.

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