SAP QUERY OPTIMIZER - Glossary

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query optimizer
The query optimizer generates the most efficient query execution plan for a given query and passes it to the executor. In SQL, there are basically two optimization tasks:

Rule-based optimization (declarative): Rewriting of the entire tree by, for example, removing joins. More efficient queries are produced at best .

Cost-based optimization (procedural): Discovering the space of access plans of the queries produced during the rule-based optimization and comparing the access plans by cost and size. The cheapest query is used for further processing.