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Exercise 4: Relation Scan Cost

Consider a table R with 105 tuples, implemented as
  • number of records/tuples r = 100,000
  • average size of records R = 200 bytes
  • size of data pages B = 4096 bytes
  • time to read one data page Tr = 10msec
  • time to check one tuple 1 usec
  • time to form one result tuple 1 usec
  • overhead from scanning one page 40 usec
Calculate the total time-cost for answering the query: 

select * from R where x > 10;

if 50% of the tuples satisfy the condition.