Query Processing and Optimization
Query Processing and Optimization : Outline
Operator Evaluation Strategies
- Query processing in general
- Selection
- Join
Query Optimization
- Heuristic query optimization
- Cost-based query optimization
Query Tuning
Query Processing + Optimization
Operator Evaluation Strategies
- Selection
- Join
Query Optimization
Query Tuning
Evaluation of SQL Statement
The query is evaluated in a different order.
- The tables in the from clause are combined using Cartesian products.
- The where predicate is then applied.
- The resulting tuples are grouped according to the group by clause.
- The having predicate is applied to each group, possibly eliminating some groups.
- The aggregates are applied to each remaining group.
- The select clause is performed last.
To know more about this topic see the given pdf :
Query Processing and Optimization – PDF
