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Ex 2: One vs Multiple Indices (cont)

For Students(id,name,gender,birthday) ...
  • calculate the size of the data file and each index
  • describe the selectivity of each attribute
Now consider a query on this relation: 

select * from Students
where  name='John' and birthday='04-01'

  • estimate the cost of answering using name index
  • estimate the cost of answering using birthday index
  • estimate the cost of answering using both indices