Hash Match, the operator

This page contains the description for my conference session “Hash Match, the operator”, and links to the slide deck and demo code used in this presentation.


Target audience Experienced database developers and DBAs, plus all curious geeks.
Short description An extremely detailed look at documented and undocumented internals of the Hash Match operator.
Duration The ideal length for this session is 120-150 minutes, though it can be shortened to 90 minutes if needed.
Full abstract SQL Server has a lot of difference execution plan operators. By far the most interesting, and the most versatile, has to be the Hash Match operator.

Hash Match is the only operator that can have either one or two inputs. It is the only operator that can either block, stream, or block partially. And it is one of just a few operators that contribute to the total memory grant of an execution plan.

If you ever looked at execution plans, you will have seen this operator. And you probably have a rough idea of what it does. But do you know EXACTLY what happens when this operator is used? In this extended 500-level session, we will dive deep into the bowels of the operator to learn how it performs.

It is going to be wild ride, so keep your hands, arms, and legs inside the conference room at all times; and please remain seated until the presenter has come to a full stop.


Click here to download a ZIP file containing the slide deck and demo code used in this presentation.

(Note: my presentations tend to evolve over time, so the version you find here may not be an exact match for the version you witnessed)

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