说明：   LiveJournal Danga Interactive is a subsidiary company of Brad Fitzpatric led the development of a software. It has now become an important factor mixi, hatena, Facebook, Vox, LiveJournal, and many other services to improve Web application scalability. Many Web applications will save the data to an RDBMS, application server which data is read and displayed in the browser. But with the increasing amount of data, centralized access, there will be a heavier burden on RDBMS in response to the deterioration, the site displays a significant impact on delays.