0 votes 0 votes Kaluti asked Sep 19, 2017 Kaluti 349 views answer comment Share Follow See all 6 Comments See all 6 6 Comments reply Kaluti commented Sep 19, 2017 reply Follow Share should not answer d here 0 votes 0 votes saxena0612 commented Sep 19, 2017 reply Follow Share Yes indeed answer should be D option because We need to find CID and TERM Altogether thus option A and B are both bad idea to implement any index .We are left with C and D though C can give solution to our problem but not efficiently because to find common tuples we again need to intersect both of them to get common tuples. THus D is correct. I think. ! 0 votes 0 votes Shubhanshu commented Sep 19, 2017 reply Follow Share @saxena0612 then what will be the Select Query for finding average grade in CS145 and Spring 1999?? 0 votes 0 votes saxena0612 commented Sep 19, 2017 reply Follow Share @Shubhanshu it will be normal query : Select Avg(grade) from enroll where Cid=cs145 and term=spring1999.Its just an index for better performance at physical level. 0 votes 0 votes Shubhanshu commented Sep 19, 2017 reply Follow Share TC = O(n). 0 votes 0 votes saxena0612 commented Sep 19, 2017 reply Follow Share At physical level i mean related to blocks since we have to traverse all blocks if there is no option thus creating an index with two search key named Cid and term will lead to better performance as in we will eventually find those blocks only and thus finding related record would be easy by then. 0 votes 0 votes Please log in or register to add a comment.