How to speed up SQL*Plus over long distances

Question

We are using Oracle 10g on Solaris 10.
We have a customer that is located several thousand miles and is accessing our database using SQL*Plus as well as a custom java app we developed. Any query our customer runs against our database is as much as 500 times slower than run locally. I ran some test queries to see just how much slower it was.
If I run this query:
SELECT id FROM test_data WHERE ROWNUM < 300000;
(The test_data table contains about 1,000,000 rows of sample data and 31 columns)
It takes about 8 seconds on our intranet. It takes about 1 – 1.3 hours for our customer.
I chose this query because I wanted a query that took at least a few seconds locally. Most of our customer’s queries return less rows, and are more complicated, but this query is easily to work with and shows what I think is the problem.
I also made a java test app the runs the same query and it also takes the same amount of time.
If I spool the results of this query to a file, it creates a 4MB file. If I ftp this file to the customer, it takes only 30 seconds. So it seems like just moving the data is not the slow part; although I am not sure this is a fair comparison.
When I run a ping between the customer and me, the average latency is 250ms. It seems like this high latency may be slowing down the transfer of query results.
I need to make the results return faster in both SQL*Plus and Java. It is not necessary to see any of the results until they have all been transferred.
Is there a way to speed this up, like sending the results all at once instead of a piece at a time? Would incressing the size of the buffers or the size of the Session Data Unit have any effect?
I am not greatly experianced with Oracle, am I misunderstanding the way it transfers data to the client?
Any suggestions would be greatly appreciated.
Tom

Answer 1

I have tried running a few qurys from the remote computer both with FLUSH ON and FLUSH OFF. The querys execute in the same amount of time either way.