SQL Server 2017 brings a new query processing methods that are designed to mitigate cardinality estimation errors in query plans and adapt plan execution based on the execution results. This innovation is called Adaptive Query Processing and consist of the three features:
- Adaptive Memory Grant Feedback;
- Interleaved Execution;
- Adaptive Joins.
We have discussed two of them in the previous posts: Adaptive Memory Grant Feedback and Interleaved Execution.
In this post, we will discuss the last one – Adaptive Joins.
Adaptive Joins were publicly introduced in the CTP 2.0, I advise you to read a post by Joe Sack Introducing Batch Mode Adaptive Joins to get know about this feature, because I will give only a brief introduction before making a deep dive into the Adaptive Join internals.