Question 1

Plan 1 and Plan 2 will not output identical row sets for all databases.
A course may be listed more than once in the output of Plan 1 for some databases.
For x = 5000, Plan 1 executes faster than Plan 2 for all databases.
For x = 9000, Plan I executes slower than Plan 2 for all databases.
       Database Management System        SOL       Gate-2006
Question 1 Explanation: 
Both plans are require the tables such as courses and enrolled to access the disks takes same time for both plans.
While analyze the plan1 and plan2 does lesser number of comparisons compared to plan1.
i) The join table consists of two tables will have more rows. So comparisons are needed to find amount greater than x.
ii) Join operation consists of more number of comparisons as the second table will have more rows in plan2 compared to plan1.
There is 1 question to complete.