是否可以从两个不同的Servlet同时访问同一个DB？

Question

I'm developing a web application, based on a DB. In my application, I access to this one from two different Servlets, and it's possible these accesses are concurrently.

I need to know if it is permitted, and if not, how can I do it? Is there some trick to perform queries in a thread-safe way?

Answer 1

It is possible and how to handle will be database responsibility based on DB settings (isolation level settings).

Here are the isolation levels in SQL Server and these may vary based on DB.

1.Read uncommitted (the lowest level where transactions are isolated only enough to ensure that physically corrupt data is not read)

2.Read committed (Database Engine default level)

3.Repeatable read

4.Serializable (the highest level, where transactions are completely isolated from one another)

Answer 2

One of the primary design requirements for databases is concurrent access. Fact is, you are most probably already doing it in any one of your servlets since they can serve several requests in parallel, usng multiple db connections. Using two connections from one app is (almost) exactly the same thing as using two connections from two apps.