Database Design

[mstczuo]

A solution for database design.
add an attribute "last_end_time" stands for the lattest end time of contests which includes this problem, so each time we can find the problems which is visible.

[leasunhy]

last end time?
I dont get your idea :-(
you mean the problem should be hidden until the last contest that uses this problem ends?
imho, the problem should become visible as soon as the earliest contest that uses the problem ends...
im getting little confused about this. please enlighten me :-)

[mstczuo]

As far as I am concerned, when a contest is running, all the problems should not be found in other place, that is why some problems should be hidden. For example, the teacher wants to start a review contest, all the problems can be found in problem list. Students may find their codes in the OJ system or submit problems outside the contest, which may reduce the number of unsucceesful submission.

[mstczuo]

Another issue:
Table "submission" needs a reference to a contest, which is useful in contest standing.

[mstczuo]

Add A Standing Table:
In our current design, we have to query the submission table and calculate the standings when a standing page HTML request is detected, which is very slow and not easy to implement.
Shall we create a new table "standing", update when a judge task finished.

[leasunhy]

hmm...
IMHO, I think a better solution would be using cache.
I believe it will outperform the add-table method.

[leasunhy]

Since applying cache functionalities is not dependent on the implementation details of our view functions, I guess that we should first finish all the modules of our oj before employing caches.