ACtE04 · Chapter 4Computer Organization & Embedded Systems🏛️ Past Licensure QuestionID: 8096eb8e
Which query-processing component evaluates the total cost of alternative execution plans?
Which query-processing component evaluates the total cost of alternative execution plans?
Multiple Choice Options
- A
Evaluator
- B
Parser
- C✓ Correct Option
Optimizer
- D
Loader
Detailed Technical Solution & Explanation
The query optimizer is the component in a database management system (DBMS) that evaluates multiple alternative execution plans for a query and selects the one with the lowest estimated cost. It considers factors like:
•
Table sizes and statistics
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Available indexes
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Join algorithms (nested loop, hash join, merge join)
•
I/O and CPU costs
Option Analysis:
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Option A (Evaluator): The query evaluator/executor runs the chosen plan — it doesn't choose between alternatives.
•
Option B (Parser): The parser checks SQL syntax and converts the query into a parse tree — no cost evaluation.
•
Option C (Optimizer): ✅ Correct. The optimizer generates and evaluates alternative plans, selecting the lowest-cost one.
•
Option D (Loader): The loader loads data or programs into memory — unrelated to query processing.
Reference: Demo · Set 4NEC Licensure Syllabus