A third option is to use separate computers, each with their own storage. However, this approach involves complex partitioning of the database, which becomes more difficult as the database increases in size and as transactions need data from different parts of a database. Simple solution Oracle's solution is deceptively simple. The cache fusion code then lets computers share data by moving it from one PC's memory, known as a buffer cache, to another's. This eliminates the need of one computer first writing the data to disk, and another computer then reading it from disk, both time-consuming tasks.
Users can increase performance by adding computers to the cluster.
One of the biggest challenges was creating the complicated algorithms that let cache fusion handle the loss of one or more computers in the cluster without losing data, Bamford says. Being able to scale the database to handle updates is critical to e-commerce sites, says Richard Winter, president of Winter Corp., a Waltham, Mass., consulting firm specializing in large database design. Running the database on large multiprocessor systems has limitations. While Web and application servers can be replicated, copying data for a site with intensive update traffic makes it hard to scale the database, Winteer says. The 9i version of the database is due for general release in March 2001.