0 votes 0 votes Kaluti asked Sep 19, 2017 Kaluti 345 views answer comment Share Follow See all 6 Comments See all 6 6 Comments reply Show 3 previous comments 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.