Question on design change

Question

Hi
I have inherited a system built using servlet/jsp.
We have a page where it displays all the orders for a customer. This page comes up really slow.
When I loop thru the code , I noticed that connections are made all over the place.
For example , To get the order header details one connection, then for every line in the order uses more new connection , then to get the details of the order line(DB contains product code ,to get description makes another connection)
This happens for every order for a customer. so I think closing and opening the connections takes a while.
I m thinking of obtaining one connection and pass it all the way down as a parameter. For this I have to change every method starting from the order level.
Is this the right way to approach it?
Please advise
TIA

Answer 1

You definitely want to share the connection. Opening and closing a connection is a relatively expensive process. Further, you will have difficulty implementing transactions (e.g. commit and rollback) without holding onto the same connection.
Consider creating two versions of each method, one that takes a Connection (or ideally, a custom Transaction object) and one that doesn't. The signature without the transaction will call the overloaded version with the transaction. This allows you to call a given method atomically (with a commit) or within another transaction (logical unit of work).
final public void foo(final int primaryKey, final String value) {
Connection conn = newConnection(); // implement somewhere else, preferably in a DAO or helper
try {
foo(primaryKey, value, conn);
finally {
if (conn != null) conn.commit();
final public void foo(final Connection connection, final int primaryKey, final String value) {
// Do work here but do not issue a commit; may issue a rollback
If you use a J2EE implementation (e.g. Weblogic, Websphere, etc.), they actually pool connections. Normally, the number of open connections on a database can be a scaling bottleneck. By pooling the connections, more threads can get access to database resources. It is a lot of overhead, and the fact it is implemented as a standard option in most containters shows how important database connection management is.
Definitely at least re-use a given connection within a logical unit or work. (Even if you do not want to create two copies of each database method). Otherwise, your application will be unecessarily slow and overuse scarce database resources.
- Saish
"My karma ran over your dogma." - Anon