Query Optimisation Plan 2 Compute the following results for the below Plan 2: The result size of the selection on vendor 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 vendor 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) Figure 3.3.2: PLAN 2. 1: The result size of the selection on Vendor 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 Vendor 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)匹配题
A
500
B
50
C
20,000
D
100
E
105
F
10,000
G
60
H
10,005
I
750
J
5
K
650
L
20,100
M
[Select this if none of the other options are correct]
N
51
O
6
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类似问题
The cut-and-try approach will always identify the aggregate plan with the lowest overall cost.
Query Optimisation Plan 1 Compute the following results for the below Plan 1: The result size of the child join in pages (marked as 'A' in the diagram) The cost of the child join in I/Os (marked as 'B' in the diagram). The cost of the parent join in I/Os (marked as 'C' in the diagram) Figure 3.3.1: PLAN 1. 1: The result size of the child join in PAGES (marked as 'A' in the diagram) 2: The cost of the child join in I/Os (marked as 'B' in the diagram) 3: The cost of the parent join in I/Os (marked as 'C' in the diagram)
Single Relation Plan C What would happen if our query changed and became: SELECT hotspotID FROM hotspot WHERE postcode = 2600 AND establishmentYear > 2020 AND establishmentYear < 2022; Assuming that the unclustered B+tree index on establishmentYear from the previous question is the only index available, would the cost of the best plan change?
Single Relation Plan B Compute the estimated cost of plan alternatives, assuming that an unclustered B+tree index on (establishmentYear) is the only index available. Suppose there are 10 index pages. Give the lowest (estimated) cost in I/Os after considering all access methods available. Round up any decimals to the nearest integer (e.g., 3.3 rounds up to 4).
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