The SQL Server Query Optimiser is a crucial component of Microsoft SQL Server, responsible for determining the most efficient way to execute a given query. The optimiser takes into consideration various factors, including the structure of the query, available indexes, statistics about the data, and the overall database schema. Here is a detailed breakdown of its functionalities, processes, and related concepts.
1. Purpose of the Query Optimiser
The primary goals of the Query Optimiser include:
- Generating Execution Plans: The optimiser creates a roadmap that describes how SQL Server will access the data required by the query.
- Maximising Efficiency: By evaluating different potential execution paths, the optimiser selects the one that minimises resource utilisation, such as CPU, memory, and disk I/O.
- Improving Response Times: A well-optimised query results in faster execution, contributing to better overall system performance.
