Questions

INFO20003_2025_SM2 MINI Practice Exam

Matching

Query Optimisation Plan Compute the following results for the below Plan 2: The result size of the selection on revenue in pages (marked as 'A' in the diagram) The result size of the child join in pages (marked as 'B' in the diagram) The cost of the selection on totalcost in I/Os (note this also accounts for the index access cost as well) (marked as 'C' in the diagram) The cost of the child join in I/Os (marked as 'D' in the diagram) The cost of the parent join in I/Os (marked as 'E' in the diagram) 1: The result size of the selection on revenue in PAGES (marked as 'A' in the diagram) 2: The result size of the child join in PAGES (marked as 'B' in the diagram) 3: The cost of the selection on totalcost in I/Os (note this also accounts for the index access cost as well) (marked as 'C' in the diagram) 4: The cost of the child join in I/Os (marked as 'D' in the diagram) 5: The cost of the parent join in I/Os (marked as 'E' in the diagram)

Options

A.6,000

B.9,040

C.9,200

D.3,000

E.24,050

F.18,040

G.6,300

H.300,000

I.3,025

J.6,050

K.12,050

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Step-by-Step Analysis

We start by restating the task and the given data so the reasoning is grounded in the exact items to be matched. - Question asks to compute five results for Plan 2: A, B, C, D, E. - The user-provided answer set (to be evaluated) is: 1) 3,000 2) 3,000 3) 3,025 4) 12,050 5) 6,300. - The answer options available for matching are: 6,000; 9,040; 9,200; 3,000; 24,050; 18,040; 6,300; 300,000; 3,025; 6,050; 12,050. Now, evaluate each item in sequence, explaining why the chosen option fits or not. I’ll consider what each item represents in the plan and how the numbers typically arise in a query optimization context. 1) The result size of the selection on revenue in PAGES (marked as 'A') - The candidate choice given is 3,000. - Reasoning: The result size of a selection on revenue depends on the selectivity of the revenue predicate and any filtering early in the plan. If the diagram/plan indicates a modest filter that reduces the input to about 3,000 pages, then 3,000 is a plausible result size for A. Alternatives like 6,000 or 9,040 would imply a larger than expected reduction or an accumulation from multiple input sources, which might not align with the depicted single-selectivity step. Very large numbers such as 300,000 would indicate an almost full-table outcome, which is unlikely for a selective reven......Login to view full explanation

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