cost-based query optimization consists of several steps.

1. Annotate resultant expressions to get alternative query plans. This step involves annotating the expressions in the query to generate different alternative plans. These alternative plans can be obtained by considering different join orders, access methods, and other optimization techniques.

2. Generating logically equivalent expressions using equivalence rules. In this step, the optimizer generates logically equivalent expressions by applying various equivalence rules. These rules help in transforming the query expressions into different forms without changing the semantics of the query.

3. Choose the cheapest plan based on estimated cost. After generating alternative query plans, the optimizer estimates the cost of each plan based on factors such as disk I/O, CPU usage, and memory consumption. The optimizer then selects the plan with the lowest estimated cost as the optimal plan for execution.

Therefore, the correct answer is option b. All of the above.

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cost-based query optimization consists of several steps.

1. Annotate resultant expressions to get alternative query plans. This step involves annotating the expressions in the query to generate different alternative plans. These alternative plans can be obtained by considering different join orders, access methods, and other optimization techniques.

2. Generating logically equivalent expressions using equivalence rules. In this step, the optimizer generates logically equivalent expressions by applying various equivalence rules. These rules help in transforming the query expressions into different forms without changing the semantics of the query.

3. Choose the cheapest plan based on estimated cost. After generating alternative query plans, the optimizer estimates the cost of each plan based on factors such as disk I/O, CPU usage, and memory consumption. The optimizer then selects the plan with the lowest estimated cost as the optimal plan for execution.

Therefore, the correct answer is option b. All of the above.

Knowee AI · Accepted Answer

cost-based query optimization consists of several steps.

1. Annotate resultant expressions to get alternative query plans. This step involves annotating the expressions in the query to generate different alternative plans. These alternative plans can be obtained by considering different join orders, access methods, and other optimization techniques.

2. Generating logically equivalent expressions using equivalence rules. In this step, the optimizer generates logically equivalent expressions by applying various equivalence rules. These rules help in transforming the query expressions into different forms without changing the semantics of the query.

3. Choose the cheapest plan based on estimated cost. After generating alternative query plans, the optimizer estimates the cost of each plan based on factors such as disk I/O, CPU usage, and memory consumption. The optimizer then selects the plan with the lowest estimated cost as the optimal plan for execution.

Therefore, the correct answer is option b. All of the above.

cost-based query optimization consist ofSelect one:a.Annotate resultant expressions to get alternative query plansb.All of the abovec.Generating logically equivalent expressions using equivalence rulesd.Choose the cheapest plan based on estimated cost

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