Transaction Test

This program finds problems with the transaction handling of the database. If the test fails, you either have a database that does not support serializable transactions or you disabled transactions using the isolation configuration parameter.

Without proper transaction handling programs with database updates can behave unexpectedly when run in parallel. This means

• Applications that just read the database are no problem
• Updates one at a time are no problem (e.g. just one person changing the database)
• Other programs might need lock statements or adhere to other restrictions in order to maintain consistency. Please carefully read the manual of your database and other documentation on database transactions.

The test is a simple web counter maintained in the database that appears 1000 times on a page. This page is loaded twice in parallel using two frames. On each page the counter should count consequtive numbers and each number should appear exactly once. The middle frame reads the counter value 1000 times and expects that it always gets the same value (not being disturbed by the conters running in the other frames).