Summary

In this chapter, we described the execution engine as a collection of physical operators, which also defines the choices that are available for the query optimizer to build execution plans with. Some of the most commonly used operators of the execution engine were introduced, including their algorithms, relative costs, and the scenarios in which the query optimizer is more likely to choose them. In particular, we looked at operators for data access, aggregations, joins, parallelism, and update operations.

Also, the concepts of sorting and hashing were introduced as a mechanism used by the execution engine to match and process data. Data access operations included the scanning of tables and indexes, the index seeks, and bookmark lookup operations. Aggregation algorithms such as Stream Aggregate and Hash Aggregate were discussed, along with join algorithms such as the Nested Loops Join, Merge Join, and Hash Join operators. Additionally, an introduction to parallelism was presented...