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Execution Plan Operator Timings

Paul White dives into a murky problem:

SQL Server 2014 SP2 and later produce runtime (“actual”) execution plans that can include elapsed time and CPU usage for each execution plan operator (see KB3170113 and this blog post by Pedro Lopes).

Interpreting these numbers is not always as straightforward as one might expect. There are important differences between row mode and batch mode execution, as well as tricky issues with row mode parallelism. SQL Server makes some timing adjustments in parallel plans to promote consistency, but they are not perfectly implemented. This can make it difficult to draw sound performance-tuning conclusions.

This article aims to help you understand where the timings come from in each case, and how they can be best interpreted in context.

My default advice is to read what Paul White writes, and this is no exception.