Today I read about java beans , servlets ,its life cycle and the advantages of using servlets than CGI(Commom Gateway Interfaces).I have solved some problems in profit and loss chapter. When I read google reader, I came to know that a column oriented database can be created and stores data vertically in table columns rather than in successive rows. Column-oriented databases minimize the time to read the disk, which can add up when executing large-scale calculations such as those typically done in a data warehouse.