In the 1990s, memory was relatively expensive and the maximum physical addressable memory was limited. Oracle systems also continued to grow larger and larger. For Oracle systems to continue to scale and support more users and processing, Oracle needed to find a solution. As shown in Figure 5-17, this solution was to allow a server process to be shared by multiple clients. This was ingenious, because for OLTP processing, server processes are more idle than busy (this is why we typically filter out the SNMFC wait event). By creating a shared-server process, Oracle systems could continue to scale.

While Oracle systems could now continue to scale, profiling a session became messy. Now that a server process could process requests from multiple clients, associating a server process activity with a specific client or a specific end user became nearly impossible without specialized tools. This core challenge remains today.

There was another force beginning to rise. As developers began to enrich the user experience and shift processing requirements away from limited database server resources, the capacity of desktop PCs increased. IT budgets started to suffer because of increased operating system and application software licenses, physical hardware costs, security-related issues, and all the related maintenance requirements.