Methods Of Query Optimization in DBMS
There are following two methods of Query Optimization in DBMS:
- Cost Based Query Optimization in DBMS
- Adaptive Query Optimization
Cost Based Query Optimization in DBMS
In Cost Based Query Optimization, optimizer associates a numerical value (known as cost) for each step of feasible plan for a given query. Then, all these values are collectively analyzed to get a cost estimate for that plan. After evaluating cost of all feasible plans, optimizer finds the plan with lowest cost estimate.
Adaptive Query Optimization in DBMS
In Adaptive Query Optimization, optimizer is allowed to make run time changes to the execution plans and can find new information to improve the optimizations. It is helpful when existing statistics are not sufficient to generate the plans.
Feature set for Adaptive Query Optimization includes:
Feature set for Adaptive Query Optimization
Advanced Query Optimization in DBMS
We will learn about advanced query optimization in DBMS. We will understand about components of optimizer and methods of query optimization. We will also understand about automatic tuning optimizers.