The basic requirement is that the navigation bar is a public part with a new reply reminder function. How to better remind new replies in the navigation bar of many current websites (such as segmentdefalut)? What I want to talk about is the solution that refreshes the page to update information. DWR is a push without refreshing. But when a general relational database is used in the background, will frequent searches have a great impact on performance? But when no optimization is done, accessing the database every time it is refreshed is obviously a waste of resources. However, if you use a general cache (the user ID and the corresponding number of new replies are placed in the cache), the cache must be updated when adding or deleting replies, and at the same time, they must be persisted. In the case of frequent replies, Will it also lead to performance degradation? I would like to ask if anyone has made a similar system and what is the general idea of implementing it? Thanks! !